aquarium.guideFish pages, lists, fit marks and tools use the tank you pick here.
Plan everything for this tank →Filters, heaters, lights and upkeep supplies, drawn at their published size on your tank and checked against the maker’s rating.
182 models
Fit marked for 20 gallon long (example)
Filters · Canister
Rated for a 20 gal tank
Consider: Allow room to lift out and service the canister. Measure its 13.7-inch height plus the hose route before choosing it for a cabinet.
Filters · Hang-on-back
Rated for a 20 gal tank
Consider: Rule it out if the trim is thicker than 13/16 inch or rear clearance is under 2.75 inches; measure both before ordering.
Filters · Hang-on-back
Rated for a 20 gal tank
Consider: Needs 3 inches behind the tank and trim no thicker than 1 inch. Measure both; a wall position that fits the Tidal 35 may not fit this model.
Filters · Hang-on-back
Rated for a 20 gal tank
Consider: Uses Medium replacement cartridges. Include their cost in your supplies plan instead of comparing the filter purchase price alone.
Filters · Hang-on-back
Rated for a 20 gal tank
Consider: Uses Large replacement cartridges. Include their cost in your supplies plan instead of comparing the filter purchase price alone.
Heaters · Adjustable, electronic
Rated for a 20 gal tank
Consider: The body is 11.75 inches tall. Check the available mounting space and water depth before choosing it for a shallow tank.
Heaters · Adjustable, electronic
Rated for a 20 gal tank
Consider: The 14-inch body can exclude shallow tanks. Compare that height with the mounting position and water depth in the instructions before ordering.
Heaters · Adjustable, electronic
Rated for a 20 gal tank
Consider: A cold room can demand more heat than the gallon rating suggests. Compare your coolest room temperature and target water temperature with the manufacturer’s sizing chart.
Heaters · Adjustable, electronic
Rated for a 20 gal tank
Consider: A cold room can demand more heat than the gallon rating suggests. Compare your coolest room temperature and target water temperature with the manufacturer’s sizing chart.
Heaters · Adjustable, electronic
Rated for a 20 gal tank
Consider: A cold room can demand more heat than the gallon rating suggests. Compare your coolest room temperature and target water temperature with the manufacturer’s sizing chart.
Heaters · Adjustable, electronic
Rated for a 20 gal tank
Consider: A cold room can demand more heat than the gallon rating suggests. Compare your coolest room temperature and target water temperature with the manufacturer’s sizing chart.
Heaters · Adjustable, electronic
Rated for a 20 gal tank
Consider: A cold room can demand more heat than the gallon rating suggests. Compare your coolest room temperature and target water temperature with the manufacturer’s sizing chart.
Heaters · Preset
Rated for a 20 gal tank
Consider: Preset to 78 °F with nothing to set: right for most tropical fish, too warm for goldfish and other cool-water fish. Choose an adjustable heater if yours need a different temperature.
Heaters · Preset
Rated for a 20 gal tank
Consider: Preset to 78 °F with nothing to set: right for most tropical fish, too warm for goldfish and other cool-water fish. Choose an adjustable heater if yours need a different temperature.
Heaters · Preset
Rated for a 20 gal tank
Consider: Preset to 78 °F with nothing to set: right for most tropical fish, too warm for goldfish and other cool-water fish. Choose an adjustable heater if yours need a different temperature.
Heaters · Preset
Rated for a 20 gal tank
Consider: Preset to 78 °F with nothing to set: right for most tropical fish, too warm for goldfish and other cool-water fish. Choose an adjustable heater if yours need a different temperature.
Heaters · Adjustable submersible
Rated for a 20 gal tank
Consider: Set it anywhere from 68 to 88 °F, a degree at a time. At 8.75 in long, check it fits upright below your water line, or lay it on its side.
Heaters · Adjustable submersible
Rated for a 20 gal tank
Consider: Set it anywhere from 68 to 88 °F, a degree at a time. At 10.325 in long, check it fits upright below your water line, or lay it on its side.
Heaters · Adjustable submersible
Rated for a 20 gal tank
Consider: Set it anywhere from 68 to 88 °F, a degree at a time. At 11.875 in long, check it fits upright below your water line, or lay it on its side.
Heaters · Adjustable submersible
Rated for a 20 gal tank
Consider: Set it anywhere from 68 to 88 °F, a degree at a time. At 13 in long, check it fits upright below your water line, or lay it on its side.
Heaters · Adjustable submersible
Rated for a 20 gal tank
Consider: Set it anywhere from 68 to 88 °F, a degree at a time. At 15.25 in long, check it fits upright below your water line, or lay it on its side.
Heaters · Preset
Rated for a 20 gal tank
Consider: Preset to 78°F with no user adjustment. Choose an adjustable heater if your fish need a different temperature.
Heaters · Adjustable, electronic
Rated for a 20 gal tank
Consider: Its published rating stops at 29 gallons. For a larger tank, use the manufacturer’s sizing guidance instead of assuming this single 100W unit is enough.
Lights · Planted LED
Spans a 30¼ in long tank
Consider: The 24–34 inch span tells you it fits your tank, not whether it lights your plants well. Compare published PAR at your water depth before choosing it for demanding plants.
Lights · Clip-on planted LED
Rated for a 20 gal tank
Consider: No built-in timer is listed. Plan how you will switch it on and off; use depth-specific light data before choosing it for demanding plants.
Air & backup · Air pump
Rated for a 20 gal tank
Consider: One outlet: a second air stone or sponge filter needs a gang valve to split the air, or a two-outlet Whisper 60 or 100.
Air & backup · Air pump
Rated for a 20 gal tank
Consider: One outlet: a second air stone or sponge filter needs a gang valve to split the air, or a two-outlet Whisper 60 or 100.
Air & backup · Air pump
Rated for a 20 gal tank
Consider: The 2.6 L/min is both outlets together, so each device gets part of it; balance two devices with the valve on each line.
Air & backup · Air pump
Rated for a 20 gal tank
Consider: The 3.3 L/min is both outlets together, so each device gets part of it; balance two devices with the valve on each line.
Air & backup · Air pump
Rated for a 20 gal tank
Consider: Tetra’s page gives no air flow or watts, so it can’t be compared with the smaller Whispers on numbers; choose it for a big or deep tank, or several air stones.
Air & backup · Air pump
Rated for a 20 gal tank
Consider: Tetra’s page gives no air flow or watts, so it can’t be compared with the smaller Whispers on numbers; choose it for a big or deep tank, or several air stones.
Lights · Planted LED
Spans a 30¼ in long tank
Consider: Operation depends on the app. Check phone compatibility before purchase, then measure the tank span against its 23–35 inch mounting range.
Filters · Hang-on-back
Rated for a 20 gal tank
Consider: The media basket lifts upward. Leave unobstructed space above the filter so routine cleaning does not require moving the tank.
Filters · Hang-on-back
Rated for a 20 gal tank
Consider: The media basket lifts upward. Leave unobstructed space above the filter so routine cleaning does not require moving the tank.
Filters · Hang-on-back
Rated for a 20 gal tank
Consider: The mechanical frame and chemical basket lift out separately. Leave overhead access for both so cleaning does not require moving the filter.
Heaters · Adjustable submersible
Rated for a 20 gal tank
Consider: A cold room or open tank changes the heating load. Use the exact-model sizing chart with your coolest room temperature before choosing from the gallon rating alone.
Filters · Hang-on-back
Rated for a 20 gal tank
Consider: Aqueon doesn’t publish the flow or the power for this unit. If running cost matters, choose a model that lists them.
Filters · Hang-on-back
Rated for a 20 gal tank
Consider: Aqueon doesn’t publish the flow or the power for this filter. If running cost matters, choose a model that lists them.
Filters · Hang-on-back
Rated for a 20 gal tank
Consider: Aqueon doesn’t publish the flow or the power for this filter. If running cost matters, choose a model that lists them.
Filters · Hang-on-back
Rated for a 20 gal tank
Consider: Aqueon doesn’t publish the flow or the power for this filter. If running cost matters, choose a model that lists them.
Filters · Hang-on-back
Rated for a 20 gal tank
Consider: Aqueon doesn’t publish the flow or the power for this filter. If running cost matters, choose a model that lists them. It takes two Large cartridges at a time.
Filters · Hang-on-back
Rated for a 20 gal tank
Consider: Its spout doubles as a drain for water changes. Aqueon doesn’t publish the flow or the power; if running cost matters, choose a model that lists them.
Filters · Hang-on-back
Rated for a 20 gal tank
Consider: Its spout doubles as a drain for water changes. Aqueon doesn’t publish the flow or the power; if running cost matters, choose a model that lists them.
Filters · Internal
Rated for a 20 gal tank
Consider: Small, and its flow turns down for small fish, but it takes room inside the tank. Aqueon doesn’t publish the power; if running cost matters, choose a model that lists it.
Filters · Canister
Rated for a 20 gal tank
Consider: It needs a 16.75 in tall spot in the cabinet, no more than 4½ ft below the water. Its rim-hung polishing unit takes a cartridge you can change in a minute without opening the canister.
Water-change tools · Gravity siphon
Rated for a 20 gal tank
Consider: Sized by Aqueon for 5 to 20 gallon tanks. The water goes into a bucket, so a big water change means several trips.
Water-change tools · Gravity siphon
Rated for a 20 gal tank
Consider: Sized by Aqueon for 15 to 35 gallon tanks. The water goes into a bucket, so a big water change means several trips.
Water-change tools · Gravity siphon
Rated for a 20 gal tank
Consider: Sized by Aqueon for 15 to 55 gallon tanks. The bulb starts the flow without pumping the tube; the water still goes into a bucket.
Air & backup · Air pump
Rated for a 20 gal tank
Consider: Its check valve is built in and Aqueon gives its watts, but not its air flow, so you can’t compare it with other pumps on air.
Air & backup · Air pump
Rated for a 20 gal tank
Consider: Its check valve is built in and Aqueon gives its watts, but not its air flow, so you can’t compare it with other pumps on air. Two outlets run two sponge filters or stones.
Filters · Canister
Rated for a 20 gal tank
Consider: At 16.5 inches it is nearly 3 inches taller than the 107 on the same footprint. Measure the cabinet height plus room to lift the motor head out before choosing it.
Filters · Hang-on-back
Rated for a 20 gal tank
Consider: The media basket lifts upward. Leave unobstructed space above the filter so routine cleaning does not require moving the tank.
Filters · Hang-on-back
Rated for a 20 gal tank
Consider: Needs 3½ inches behind the tank and trim no thicker than 1 5/16 inches. Measure both; a wall position that fits the Tidal 55 may not fit this model.
Filters · Hang-on-back
Rated for a 20 gal tank
Consider: Needs 4 inches behind the tank and 2 inches inside it below the rim. Measure both before choosing it over the Tidal 75.
Filters · Canister
Rated for a 20 gal tank
Consider: It needs a 13.4 × 13.4 inch patch of cabinet floor and room above to lift the lid. Measure the inside of the cabinet, not the door, before choosing it.
Filters · Canister
Rated for a 20 gal tank
Consider: It needs a 15.75 × 15.75 inch patch of cabinet floor and room above to lift the lid. Measure the inside of the cabinet, between any center brace and the door frame, before choosing it.
Filters · Canister
Rated for a 20 gal tank
Consider: At 20.8 inches tall it fits under fewer stands than the FX4 on the same footprint. Measure the cabinet height plus room to lift the lid before choosing it.
Heaters · Adjustable submersible
Rated for a 20 gal tank
Consider: A cold room or open tank changes the heating load. Use the exact-model sizing chart with your coolest room temperature before choosing from the gallon rating alone.
Heaters · Adjustable submersible
Rated for a 20 gal tank
Consider: A cold room or open tank changes the heating load. Use the exact-model sizing chart with your coolest room temperature before choosing from the gallon rating alone.
Heaters · Adjustable submersible
Rated for a 20 gal tank
Consider: At 15 inches it is the longest M heater. Check it fits your water depth at the angle you mount it, and size for your coolest room, not the gallon rating alone.
Heaters · Adjustable, electronic
Rated for a 20 gal tank
Consider: The 14-inch body can exclude shallow tanks. Compare that height with the mounting position and water depth in the instructions before ordering.
Heaters · Adjustable submersible
Rated for a 20 gal tank
Consider: There is no display: you set it on a dial, check the water with a thermometer and recalibrate the dial if the two disagree.
Filters · Hang-on-back
Rated for a 20 gal tank
Consider: Its skimmer can pull in baby shrimp and very small fish: hygger’s answer is a piece of sponge or mesh over the skimmer’s intake. Expect it to gurgle for the first hours, or up to two days, while the air works out of the box.
Filters · Hang-on-back
Rated for a 20 gal tank
Consider: Its skimmer can pull in baby shrimp and very small fish: hygger’s answer is a piece of sponge or mesh over the skimmer’s intake. Expect it to gurgle for the first hours, or up to two days, while the air works out of the box.
Lights · Planted LED
Spans a 30¼ in long tank
Consider: Plug it in, set the clock and it runs the day on its own: full-spectrum light from 6:30 am to 6:30 pm, then blue until 11:30 pm. For less than full brightness use the DIY mode, since the standard mode goes back to 100% each day.
Filters · Hang-on-back
Rated for a 20 gal tank
Consider: The mechanical frame and chemical basket lift out separately. Leave overhead access for both so cleaning does not require moving the filter.
Filters · Hang-on-back
Rated for a 20 gal tank
Consider: The mechanical frame and chemical basket lift out separately. Leave overhead access for both so cleaning does not require moving the filter.
Filters · Internal
Rated for a 20 gal tank
Consider: It sits inside the tank, so measure the space it needs: 8 × 3.5 × 4 in, plus room to tilt it off its bracket. Fluval says it can lie on its side in a shallow tank.
Filters · Internal
Rated for a 20 gal tank
Consider: It sits inside the tank, so measure the space it needs: 10.5 × 3.25 × 4 in, plus room to tilt it off its bracket. Fluval says it can lie on its side in a shallow tank.
Filters · Internal
Rated for a 20 gal tank
Consider: It sits inside the tank, so measure the space it needs: 13 × 4 × 4.5 in, plus room to tilt it off its bracket. Fluval says it can lie on its side in a shallow tank.
Filters · Hang-on-back
Rated for a 20 gal tank
Consider: It runs on Marineland’s Rite-Size cartridges, so budget for replacements; the BIO-Wheel that spins in the outflow carries the filter’s bacteria and stays in place when you change a cartridge.
Filters · Hang-on-back
Rated for a 20 gal tank
Consider: It runs on Marineland’s Rite-Size cartridges, so budget for replacements; the BIO-Wheel that spins in the outflow carries the filter’s bacteria and stays in place when you change a cartridge.
Filters · Hang-on-back
Rated for a 20 gal tank
Consider: It runs on Marineland’s Rite-Size cartridges, so budget for replacements; the BIO-Wheel that spins in the outflow carries the filter’s bacteria and stays in place when you change a cartridge.
Filters · Hang-on-back
Rated for a 20 gal tank
Consider: It runs on Marineland’s Rite-Size cartridges, so budget for replacements; the BIO-Wheel that spins in the outflow carries the filter’s bacteria and stays in place when you change a cartridge.
Filters · Canister
Rated for a 20 gal tank
Consider: Its valve block makes cleaning day easier: close it and the hoses stay full while the canister comes away. Marineland’s page gives no size, watts or box contents, so check those on the box.
Filters · Canister
Rated for a 20 gal tank
Consider: Its valve block makes cleaning day easier: close it and the hoses stay full while the canister comes away. Marineland’s page gives no size, watts or box contents, so check those on the box.
Filters · Canister
Rated for a 20 gal tank
Consider: Its valve block makes cleaning day easier: close it and the hoses stay full while the canister comes away. Marineland’s page gives no size, watts or box contents, so check those on the box.
Filters · Hang-on-back
Rated for a 20 gal tank
Consider: It runs on EHEIM’s own cartridges, so replacements come from EHEIM. EHEIM says the water slide keeps the return quiet, and the intake pipe’s depth changes how the water moves in the tank.
Filters · Hang-on-back
Rated for a 20 gal tank
Consider: It runs on EHEIM’s own cartridges, so replacements come from EHEIM. EHEIM says the water slide keeps the return quiet, and the intake pipe’s depth changes how the water moves in the tank.
Filters · Sponge
Rated for a 20 gal tank
Consider: The flow is too gentle to catch fins or baby shrimp, but it needs an air pump, airline and check valve, sold separately, and it sits inside the tank.
Filters · Sponge
Rated for a 20 gal tank
Consider: The flow is too gentle to catch fins or baby shrimp, but it needs an air pump, airline and check valve, sold separately, and it sits inside the tank.
Filters · Sponge
Rated for a 20 gal tank
Consider: Two sponges give it more surface than a single sponge filter, but it needs an air pump, sold separately, and stands inside the tank.
Filters · Sponge
Rated for a 20 gal tank
Consider: Two sponges give it more surface than a single sponge filter, but it needs an air pump, sold separately, and stands inside the tank.
Heaters · Adjustable, electronic
Rated for a 20 gal tank
Consider: The controller stays dry outside the tank and remembers your setting through a power cut, but the glass tube has no guard around it.
Heaters · Adjustable, electronic
Rated for a 20 gal tank
Consider: The controller stays dry outside the tank and remembers your setting through a power cut, but the glass tube has no guard around it.
Heaters · Adjustable, electronic
Rated for a 20 gal tank
Consider: Titanium won’t shatter like glass, and the controller remembers your setting through a power cut, but the heater and its sensor are two pieces to place in the tank.
Filters · Hang-on-back
Rated for a 20 gal tank
Consider: You can see the waste it has caught and flush it out without a gravel vacuum, but it takes glass or a rim only up to 0.47 in thick, and its skimmer can pull in baby shrimp and small fish unless you cover it.
Filters · Hang-on-back
No published tank rating
Consider: Uses Large Bio-Bag cartridges. Include replacements in the yearly cost; its adjustable 10–130 GPH range doesn’t tell you what tank size it suits.
Filters · Hang-on-back
No published tank rating
Consider: Its 20 GPH minimum is higher than the IQ 20’s 10 GPH minimum. If very gentle output is the priority, compare that lower-flow model before choosing.
Filters · Sponge
Listed from 5 gal; no maximum published
Consider: Budget for an air pump, airline and check valve. Check the water depth against the uplift tube before choosing it for a shallow tank.
Filters · Sponge
Listed from 10 gal; no maximum published
Consider: It has no built-in motor. Choose and budget an air pump and airline together with the filter; the pump and water depth affect delivered flow.
Water testing · Liquid test kit
Consider: No GH or KH: add API’s GH & KH kit for shrimp, soft-water fish or plants.
Water testing · Liquid test kit
Consider: KH only. If your fish or plants need a set hardness, API’s GH & KH kit tests both.
Water testing · Liquid test kit
Consider: Hardness only: no pH, ammonia, nitrite or nitrate. It pairs with the Freshwater Master Test Kit, which has those and not these.
Water testing · Test strips
Consider: Quick, but no ammonia pad. While a new tank cycles, add API’s ammonia strips or a liquid ammonia test.
Water testing · Test strips
Consider: One reading, ammonia, per strip. A liquid kit reads a wider range, up to 8 ppm in API’s.
Water testing · Liquid test kit
Consider: Ammonia only. The Freshwater Master Test Kit includes an ammonia test along with pH, nitrite and nitrate.
Water testing · Liquid test kit
Consider: Nitrite only. The Freshwater Master Test Kit includes it with ammonia, nitrate and pH.
Water testing · Liquid test kit
Consider: Nitrate only. The Freshwater Master Test Kit includes it with ammonia, nitrite and pH.
Water testing · Test strips
Consider: No ammonia pad. Tetra sells ammonia strips separately and in its Complete kit.
Water testing · Test strips
Consider: Ammonia only. The Complete kit pairs it with the 6-in-1 strips.
Water testing · Test strips
Consider: The same two strips Tetra sells separately, in one box.
Water testing · Liquid test kit
Consider: Ammonia only, and more steps than a strip. It is the one to use if you dose Prime or another ammonia binder.
Water testing · Liquid test kit
Consider: No ammonia: pair it with MultiTest Ammonia or another ammonia test.
Water conditioner · Dechlorinator
Consider: Small water changes need small measured amounts. Use a graduated measuring tool and the exact bottle instructions; do not estimate tiny doses by eye.
Thermometers · Stick-on digital strip
Consider: The display covers 64–86°F. Choose another thermometer if your planned water temperature falls outside that range.
Water-change tools · Gravity siphon
Consider: It has no squeeze bulb or flow guard. Choose another design if you need those features, and keep the intake away from small animals while controlling the flow.
Air & backup · Battery backup air pump
Consider: Battery runtime varies with age, depth and airflow, and the maker’s runtime figures cover units sold since 2024-08-01. Test it with your own tubing and diffuser before relying on the stated outage duration.
Air & backup · Battery backup air pump
Consider: The stated airflow is a total, not a promise for each outlet. Test both connected devices together and balance their air delivery before relying on the backup. The maker’s runtime figures cover units sold since 2024-08-01.
Water-change tools · Intake prefilter sponge
Consider: Intake fit is model-specific. Use the published compatibility chart and measure the intake; inspect foam condition instead of treating it as a guaranteed barrier for tiny animals.
Water-change tools · Gravity siphon
Listed from 40 gal; no maximum published
Consider: Sized by Aqueon for 40 gallon and bigger tanks. The water goes into a bucket, so a big water change means several trips.
Water-change tools · Faucet water changer
Consider: No buckets to carry, but it needs a sink faucet within 25 ft of the tank that takes its adapter.
Water-change tools · Faucet water changer
Consider: No buckets to carry, but it needs a sink faucet within 50 ft of the tank that takes its adapter.
Filters · Canister
Rated 40–70 gal, not 20 gal
Consider: A cabinet that fits the body can still leave too little hose or service room. Measure the full route and removal space before choosing this larger canister.
Heaters · Flat
Rated 1–3 gal, not 20 gal
Consider: Small and flat, with no temperature to set: it adds up to 6 °F to the room, so a 78 °F tank needs a room of 72 °F or warmer, day and night.
Heaters · Flat
Rated 5–10 gal, not 20 gal
Consider: Small and flat, with no temperature to set: it adds up to 6 °F to the room, so a 78 °F tank needs a room of 72 °F or warmer, day and night.
Heaters · Preset
Rated 2–10 gal, not 20 gal
Consider: Preset to 78°F with no user adjustment. Choose an adjustable heater if your fish need a different temperature.
Lights · Planted LED
Spans 15–24 in; this tank is 30¼ in long
Consider: App control is part of the setup. Check that your phone supports the Fluval app, then measure the tank span against the 15–24 inch mounting range.
Lights · Planted LED
Spans 24 in; this tank is 30¼ in long
Consider: No depth-specific PAR table is published. For demanding plants or a deep tank, compare a fixture with published measurements at the relevant depth.
Lights · Planted LED
Spans 36 in; this tank is 30¼ in long
Consider: No depth-specific PAR table is published. For demanding plants or a deep tank, compare a fixture with published measurements at the relevant depth.
Air & backup · Air pump
Rated up to 10 gal, not 20 gal
Consider: One outlet: a second air stone or sponge filter needs a gang valve to split the air, or a two-outlet Whisper 60 or 100.
Lights · Planted LED
Spans 15–24 in; this tank is 30¼ in long
Consider: Operation depends on the app. Check phone compatibility before purchase, then measure the tank span against its 15–24 inch mounting range.
Heaters · Adjustable submersible
Rated up to 15 gal, not 20 gal
Consider: A cold room or open tank changes the heating load. Use the exact-model sizing chart with your coolest room temperature before choosing from the gallon rating alone.
Filters · Hang-on-back
Rated 30–50 gal, not 20 gal
Consider: Its spout doubles as a drain for water changes. Aqueon doesn’t publish the flow or the power; if running cost matters, choose a model that lists them.
Filters · Hang-on-back
Rated 50–90 gal, not 20 gal
Consider: Its spout doubles as a drain for water changes. Aqueon doesn’t publish the flow or the power; if running cost matters, choose a model that lists them.
Filters · Internal
Rated up to 5 gal, not 20 gal
Consider: Small, and its flow turns down for small fish, but it takes room inside the tank. Aqueon doesn’t publish the power; if running cost matters, choose a model that lists it.
Filters · Internal
Rated 5–15 gal, not 20 gal
Consider: Small, and its flow turns down for small fish, but it takes room inside the tank. Aqueon doesn’t publish the power; if running cost matters, choose a model that lists it.
Filters · Air-driven
Rated up to 3 gal, not 20 gal
Consider: Gentle air-driven flow for a betta, but it needs an air pump, sold separately, and Aqueon makes it only for bowls and tanks up to 3 gallons.
Filters · Canister
Rated 55–75 gal, not 20 gal
Consider: It needs a 17 in tall spot in the cabinet, no more than 4½ ft below the water. Its rim-hung polishing unit takes a cartridge you can change in a minute without opening the canister.
Filters · Canister
Rated 100–150 gal, not 20 gal
Consider: It needs a 19.875 in tall spot in the cabinet, no more than 4½ ft below the water. Its rim-hung polishing unit takes a cartridge you can change in a minute without opening the canister.
Water-change tools · Gravity siphon
Rated 1–5 gal, not 20 gal
Consider: Sized by Aqueon for 1 to 5 gallon tanks. The water goes into a bucket, so a big water change means several trips.
Air & backup · Air pump
Rated 2–10 gal, not 20 gal
Consider: Its check valve is built in and Aqueon gives its watts, but not its air flow, so you can’t compare it with other pumps on air.
Filters · Canister
Rated 50–100 gal, not 20 gal
Consider: At 19.3 inches it is the tallest 07 canister. A cabinet that fits the body can still leave too little room to lift the head and baskets out; measure before choosing.
Filters · Hang-on-back
Rated 40–70 gal, not 20 gal
Consider: At 6.1 inches deep it stands much further off the back glass than the AC50. Measure the gap to the wall and the space above the lid before choosing it.
Filters · Hang-on-back
Rated 60–110 gal, not 20 gal
Consider: It is 13.6 inches wide. Check that a clear stretch of rim that long sits between the lid hinges, braces and other equipment before choosing it.
Heaters · Preset
Rated 30–40 gal, not 20 gal
Consider: Preset to 78°F with no user adjustment. Choose an adjustable heater if your fish need a different temperature.
Heaters · Preset
Rated 40–55 gal, not 20 gal
Consider: Preset to 78°F with no user adjustment. Choose an adjustable heater if your fish need a different temperature.
Heaters · Adjustable submersible
Rated 5.2–6.6 gal, not 20 gal
Consider: There is no display: you set it on a dial, check the water with a thermometer and recalibrate the dial if the two disagree.
Heaters · Adjustable submersible
Rated 6.6–15.8 gal, not 20 gal
Consider: There is no display: you set it on a dial, check the water with a thermometer and recalibrate the dial if the two disagree.
Heaters · Adjustable submersible
Rated 26.4–39.6 gal, not 20 gal
Consider: There is no display: you set it on a dial, check the water with a thermometer and recalibrate the dial if the two disagree.
Heaters · Adjustable submersible
Rated 39.6–53 gal, not 20 gal
Consider: There is no display: you set it on a dial, check the water with a thermometer and recalibrate the dial if the two disagree.
Heaters · Adjustable submersible
Rated 53–79 gal, not 20 gal
Consider: There is no display: you set it on a dial, check the water with a thermometer and recalibrate the dial if the two disagree.
Heaters · Adjustable submersible
Rated 79–106 gal, not 20 gal
Consider: There is no display: you set it on a dial, check the water with a thermometer and recalibrate the dial if the two disagree.
Heaters · Adjustable submersible
Rated 106–159 gal, not 20 gal
Consider: There is no display: you set it on a dial, check the water with a thermometer and recalibrate the dial if the two disagree.
Heaters · Adjustable submersible
Rated 159–264 gal, not 20 gal
Consider: There is no display: you set it on a dial, check the water with a thermometer and recalibrate the dial if the two disagree.
Heaters · Adjustable, electronic
Rated 0.4–2.64 gal, not 20 gal
Consider: Made for small tanks: it mounts upright or lying flat, even in the back chamber of an all-in-one tank, and the controller on its cord shows the water temperature.
Heaters · Adjustable, electronic
Rated 0.4–5.3 gal, not 20 gal
Consider: Made for small tanks: it mounts upright or lying flat, even in the back chamber of an all-in-one tank, and the controller on its cord shows the water temperature.
Heaters · Adjustable, electronic
Rated 0.4–11.9 gal, not 20 gal
Consider: Made for small tanks: it mounts upright or lying flat, even in the back chamber of an all-in-one tank, and the controller on its cord shows the water temperature.
Heaters · Adjustable, electronic
Rated 0.4–15.9 gal, not 20 gal
Consider: Made for small tanks: it mounts upright or lying flat, even in the back chamber of an all-in-one tank, and the controller on its cord shows the water temperature.
Filters · Hang-on-back
Rated up to 10 gal, not 20 gal
Consider: Its skimmer can pull in baby shrimp and very small fish: hygger’s answer is a piece of sponge or mesh over the skimmer’s intake. Expect it to gurgle for the first hours, or up to two days, while the air works out of the box.
Filters · Hang-on-back
Rated 40–60 gal, not 20 gal
Consider: Its skimmer can pull in baby shrimp and very small fish: hygger’s answer is a piece of sponge or mesh over the skimmer’s intake. Expect it to gurgle for the first hours, or up to two days, while the air works out of the box.
Lights · Planted LED
Spans 12–18 in; this tank is 30¼ in long
Consider: Plug it in, set the clock and it runs the day on its own: full-spectrum light from 6:30 am to 6:30 pm, then blue until 11:30 pm. For less than full brightness use the DIY mode, since the standard mode goes back to 100% each day.
Lights · Planted LED
Spans 18–24 in; this tank is 30¼ in long
Consider: Plug it in, set the clock and it runs the day on its own: full-spectrum light from 6:30 am to 6:30 pm, then blue until 11:30 pm. For less than full brightness use the DIY mode, since the standard mode goes back to 100% each day.
Lights · Planted LED
Spans 24–30 in; this tank is 30¼ in long
Consider: Plug it in, set the clock and it runs the day on its own: full-spectrum light from 6:30 am to 6:30 pm, then blue until 11:30 pm. For less than full brightness use the DIY mode, since the standard mode goes back to 100% each day.
Lights · Planted LED
Spans 36–42 in; this tank is 30¼ in long
Consider: Plug it in, set the clock and it runs the day on its own: full-spectrum light from 6:30 am to 6:30 pm, then blue until 11:30 pm. For less than full brightness use the DIY mode, since the standard mode goes back to 100% each day.
Lights · Planted LED
Spans 48–55 in; this tank is 30¼ in long
Consider: Plug it in, set the clock and it runs the day on its own: full-spectrum light from 6:30 am to 6:30 pm, then blue until 11:30 pm. For less than full brightness use the DIY mode, since the standard mode goes back to 100% each day.
Lights · Planted LED
Spans 36–46 in; this tank is 30¼ in long
Consider: App control is part of the setup. Check that your phone supports the Fluval app, then measure the tank span against the 36–46 inch mounting range.
Lights · Planted LED
Spans 48–60 in; this tank is 30¼ in long
Consider: App control is part of the setup. Check that your phone supports the Fluval app, then measure the tank span against the 48–60 inch mounting range.
Lights · Planted LED
Spans 35–49 in; this tank is 30¼ in long
Consider: Operation depends on the app. Check phone compatibility before purchase, then measure the tank span against its 35–49 inch mounting range.
Lights · Planted LED
Spans 46.25–61 in; this tank is 30¼ in long
Consider: Operation depends on the app. Check phone compatibility before purchase, then measure the tank span against its 46¼–61 inch mounting range.
Filters · Internal
Rated up to 15 gal, not 20 gal
Consider: It sits inside the tank, so measure the space it needs: 4 × 3 × 6 in, plus room to tilt it off its bracket. Fluval says it can lie on its side in a shallow tank.
Filters · Canister
Rated 21–66 gal, not 20 gal
Consider: It has no priming button and no hose valves in the box: you start it by sucking on the outlet elbow until water flows, as EHEIM’s manual shows.
Filters · Canister
Rated 31–92 gal, not 20 gal
Consider: It has no priming button and no hose valves in the box: you start it by sucking on the outlet elbow until water flows, as EHEIM’s manual shows.
Filters · Canister
Rated 47–159 gal, not 20 gal
Consider: It has no priming button and no hose valves in the box: you start it by sucking on the outlet elbow until water flows, as EHEIM’s manual shows.
Filters · Canister
Rated 31–65 gal, not 20 gal
Consider: The square canister is 9.4 in wide and 9.6 in deep, so it needs more cabinet floor than EHEIM’s round classic for the same tank; in return the prefilter on top takes the coarse dirt, and the baskets lift out for cleaning.
Filters · Canister
Rated 47–92 gal, not 20 gal
Consider: The square canister is 9.4 in wide and 9.6 in deep, so it needs more cabinet floor than EHEIM’s round classic for the same tank; in return the prefilter on top takes the coarse dirt, and the baskets lift out for cleaning.
Filters · Canister
Rated 63–158 gal, not 20 gal
Consider: The square canister is 9.4 in wide and 9.6 in deep, so it needs more cabinet floor than EHEIM’s round classic for the same tank; in return the prefilter on top takes the coarse dirt, and the baskets lift out for cleaning.
Filters · Hang-on-back
Rated up to 19.8 gal, not 20 gal
Consider: It runs on EHEIM’s own cartridges, so replacements come from EHEIM. EHEIM says the water slide keeps the return quiet, and the intake pipe’s depth changes how the water moves in the tank.
Filters · Sponge
Rated 55–125 gal, not 20 gal
Consider: The flow is too gentle to catch fins or baby shrimp, but it needs an air pump, airline and check valve, sold separately, and it sits inside the tank.
Filters · Hang-on-back
Rated 7–10 gal, not 20 gal
Consider: The media box stays outside the tank and takes any media you choose, but hygger makes this size only for 7 to 10 gallons.
Filters · Hang-on-back
Rated 12–17 gal, not 20 gal
Consider: The media box stays outside the tank and takes any media you choose, but hygger makes this size only for 12 to 17 gallons.
Heaters · Adjustable, electronic
Rated 5–10 gal, not 20 gal
Consider: The controller stays dry outside the tank and remembers your setting through a power cut, but the glass tube has no guard around it.
Heaters · Adjustable, electronic
Rated 40–60 gal, not 20 gal
Consider: The controller stays dry outside the tank and remembers your setting through a power cut, but the glass tube has no guard around it.
Heaters · Adjustable, electronic
Rated 55–100 gal, not 20 gal
Consider: The controller stays dry outside the tank and remembers your setting through a power cut, but the glass tube has no guard around it.
Heaters · Adjustable, electronic
Rated 10–15 gal, not 20 gal
Consider: Titanium won’t shatter like glass, and the controller remembers your setting through a power cut, but the heater and its sensor are two pieces to place in the tank.
Heaters · Adjustable, electronic
Rated 30–40 gal, not 20 gal
Consider: Titanium won’t shatter like glass, and the controller remembers your setting through a power cut, but the heater and its sensor are two pieces to place in the tank.
Heaters · Adjustable, electronic
Rated 50–60 gal, not 20 gal
Consider: Titanium won’t shatter like glass, and the controller remembers your setting through a power cut, but the heater and its sensor are two pieces to place in the tank.
Heaters · Adjustable, electronic
Rated 70–80 gal, not 20 gal
Consider: Titanium won’t shatter like glass, and the controller remembers your setting through a power cut, but the heater and its sensor are two pieces to place in the tank.
Filters · Hang-on-back
Rated 5–20 gal, but this tank is too long for it
Consider: You can see the waste it has caught and flush it out without a gravel vacuum, but it takes glass or a rim only up to 0.47 in thick, and its skimmer can pull in baby shrimp and small fish unless you cover it.
Filters · Hang-on-back
Rated up to 5 gal, not 20 gal
Consider: Quiet (hygger gives 35 dB or less) and light on power, but it is made for rimless tanks only: the plastic frame of a rimmed tank won’t take it.
Filters · Hang-on-back
Rated 5–10 gal, not 20 gal
Consider: Quiet (hygger gives 35 dB or less) and light on power, but it is made for rimless tanks only: the plastic frame of a rimmed tank won’t take it.
Filters · Hang-on-back
Rated 10–20 gal, but made for rimless tanks only
Consider: Quiet (hygger gives 35 dB or less) and light on power, but it is made for rimless tanks only: the plastic frame of a rimmed tank won’t take it.
Clear the search or choose another tank size. The size filter only shows filters and heaters that their maker rates for that size.
The size filter and the fit marks use each maker’s tank-size rating for filters and heaters and the fixture span for lights. Drawings use the makers’ published sizes; positions are approximate. Where a maker doesn’t publish a rating, we don’t guess one; each model page says what is missing.
Find filters, heaters, lights and maintenance supplies for your freshwater tank. Compare sizes, controls and cleaning access before you choose.
Check these against your tank in the equipment planner. Replaced and renamed models.
Every size by maker: API · Aquarium Co-Op · Aqueon · EHEIM · Fluval · Marineland · Seachem · Tetra · hygger
