Sized for a 20 gallon tank
| Model | Rated for | Moves your water | Room it needs |
|---|---|---|---|
| Aqueon PRO QuietFlow Power Filter 10 Hang-on-back | Up to 20 gal | Not published | 3.8 in deep, behind the tank |
| Aqueon QuietFlow LED PRO 10 Hang-on-back | Up to 20 gal | Not published | 3.625 in deep, behind the tank |
| Aqueon SmartClean Power Filter 10–20 gal Hang-on-back | 10–20 gal | Not published | Not published |
| Fluval AC20 Hang-on-back | 5–20 gal | 5× an hour (100 GPH at most) | 4.4 in deep, behind the tank |
| hygger Biochemical Sponge Filter, Small Sponge, runs from an air pump sold separately | 5–20 gal | Not published | 2.9 × 2.9 × 4.4 in, inside the tank |
| hygger Hang-on-back Canister Filter 6W Hang-on-back | 10–20 gal | 5× an hour (100 GPH at most) | Not published |
| Marineland Penguin PRO 125 Hang-on-back | Up to 20 gal | 6.3× an hour (125 GPH at most) | Not published |
| Aqueon PRO QuietFlow Power Filter 20 Hang-on-back | Up to 30 gal | Not published | 4.25 in deep, behind the tank |
| Aqueon QuietFlow Internal Power Filter 15–30 gal Internal | 15–30 gal | 7.5× an hour (150 GPH at most) | 5.5 × 4 × 8 in, inside the tank |
| Aqueon QuietFlow LED PRO 20 Hang-on-back | Up to 30 gal | Not published | 4.25 in deep, behind the tank |
| Aqueon SmartClean Power Filter 20–30 gal Hang-on-back | 20–30 gal | Not published | Not published |
| Fluval 107 Canister | 10–30 gal | 4.8× an hour (95 GPH through the filter) | 13.7 in tall, in the cabinet |
| Fluval AC30 Hang-on-back | 10–30 gal | 7.5× an hour (150 GPH at most) | 4.4 in deep, behind the tank |
| Fluval C2 Hang-on-back | Up to 30 gal | 6× an hour (119 GPH through the filter) | 4.7 in deep, behind the tank |
| Fluval U2 Internal | Up to 30 gal | 5.3× an hour (105 GPH pump rating) | 8 × 3.5 × 4 in, inside the tank |
| hygger Backpack Aquarium Filter 8W Hang-on-back · Rated 15–30 gal, which covers 20 gallons; hygger makes it for tanks 19.7 to 31.5 in long and 9.8 to 15.7 in tall, so the 20 gallon long, not the 20 gallon high. | 15–30 gal | 7.9× an hour (158 GPH at most) | 3.9 in deep, behind the tank |
| Marineland Magniflow 160 Canister | Up to 30 gal | 8× an hour (160 GPH at most) | Not published |
| Marineland Penguin PRO 175 Hang-on-back | Up to 30 gal | 8.8× an hour (175 GPH at most) | Not published |
| EHEIM LiBERTY 130 (2041) Hang-on-back | Up to 34.3 gal | 7.6× an hour (151 GPH at most) | 5.3 in deep, behind the tank |
| Seachem Tidal 35 Hang-on-back | Up to 35 gal | 6.5× an hour (130 GPH at most) | 5.125 in deep, behind the tank |
| Fluval U3 Internal | Up to 40 gal | 7.8× an hour (155 GPH pump rating) | 10.5 × 3.25 × 4 in, inside the tank |
| hygger Double Biochemical Sponge Filter, Small Sponge, runs from an air pump sold separately | 10–40 gal | Not published | Not published |
| hygger Hang-on-back Canister Filter 7W Hang-on-back | 20–40 gal | 7.7× an hour (153 GPH at most) | Not published |
| Aqueon PRO QuietFlow Power Filter 30 Hang-on-back | Up to 45 gal | Not published | 4.375 in deep, behind the tank |
| Fluval 207 Canister | 20–45 gal | 6.1× an hour (121 GPH through the filter) | 16.5 in tall, in the cabinet |
| Aqueon PRO QuietFlow Power Filter 50 Hang-on-back | Up to 50 gal | Not published | 4.375 in deep, behind the tank |
| Fluval AC50 Hang-on-back | 20–50 gal | 10× an hour (200 GPH at most) | 4.4 in deep, behind the tank |
| Fluval C3 Hang-on-back | Up to 50 gal | 7.7× an hour (153 GPH through the filter) | 4.7 in deep, behind the tank |
| Marineland Penguin PRO 275 Hang-on-back | Up to 50 gal | 13.8× an hour (275 GPH at most) | Not published |
| EHEIM LiBERTY 200 (2042) Hang-on-back | Up to 52.8 gal | 10.1× an hour (201 GPH at most) | 5.3 in deep, behind the tank |
| Aqueon QuietFlow Canister Filter 200 Canister | Up to 55 gal | 10× an hour (200 GPH pump rating) | 16.75 in tall, in the cabinet |
| hygger Biochemical Sponge Filter, Medium Sponge, runs from an air pump sold separately | 20–55 gal | Not published | 2.9 × 2.9 × 6.5 in, inside the tank |
| hygger Double Biochemical Sponge Filter, Medium Sponge, runs from an air pump sold separately | 15–55 gal | Not published | Not published |
| Marineland Magniflow 220 Canister | Up to 55 gal | 11× an hour (220 GPH at most) | Not published |
| Seachem Tidal 55 Hang-on-back | Up to 55 gal | 12.5× an hour (250 GPH at most) | 6.125 in deep, behind the tank |
| Aquarium Co-Op Easy Flow Sponge Filter, Small Sponge, runs from an air pump sold separately | 10 gal and up | Not published | Not published |
Turnover here is the maker’s figure for a clean filter. Real flow drops as the media fills and the water has further to climb, so a filter near the bottom of that column has the least to spare. Slow swimmers such as bettas want gentle water: choose one with a flow control, or see how to read flow ratings.
Rated for it, but more than it needs
These cover 20 gallons on paper, but their ratings run past 3 times that: more flow, a bigger body and more cost than the tank needs.
- Fluval U4: Rated up to 65 gal: it covers 20 gallons, but it is built for tanks over 3 times that size.
- Fluval C4: Rated up to 70 gal: it covers 20 gallons, but it is built for tanks over 3 times that size.
- Marineland Penguin PRO 375: Rated up to 75 gal: it covers 20 gallons, but it is built for tanks over 3 times that size.
- Seachem Tidal 75: Rated up to 75 gal: it covers 20 gallons, but it is built for tanks over 3 times that size.
- Aqueon PRO QuietFlow Power Filter 75: Rated up to 90 gal: it covers 20 gallons, but it is built for tanks over 3 times that size.
- Marineland Magniflow 360: Rated up to 100 gal: it covers 20 gallons, but it is built for tanks over 3 times that size.
- Seachem Tidal 110: Rated up to 110 gal: it covers 20 gallons, but it is built for tanks over 3 times that size.
- Fluval FX2: Rated up to 175 gal: it covers 20 gallons, but it is built for tanks over 3 times that size.
- Fluval FX4: Rated up to 250 gal: it covers 20 gallons, but it is built for tanks over 3 times that size.
- Fluval FX6: Rated up to 400 gal: it covers 20 gallons, but it is built for tanks over 3 times that size.
Not for a 20 gallon tank
- Aqueon Betta Filter: Rated up to 3 gal: too small for 20 gallons.
- Aqueon QuietFlow Internal Power Filter up to 5 gal: Rated up to 5 gal: too small for 20 gallons.
- hygger Cleanness Hang On Filter 3.5W: Rated up to 5 gal: too small for 20 gallons.
- hygger AquaFall Aquarium Filter, S: Rated 7–10 gal: too small for 20 gallons.
- hygger Cleanness Hang On Filter 4.5W: Rated 5–10 gal: too small for 20 gallons.
- hygger Hang-on-back Canister Filter 5W: Rated up to 10 gal: too small for 20 gallons.
- Aqueon QuietFlow Internal Power Filter 5–15 gal: Rated 5–15 gal: too small for 20 gallons.
- Fluval U1: Rated up to 15 gal: too small for 20 gallons.
- hygger AquaFall Aquarium Filter, M: Rated 12–17 gal: too small for 20 gallons.
- EHEIM LiBERTY 75 (2040): Rated up to 19.8 gal: too small for 20 gallons.
- hygger Backpack Aquarium Filter 6W: Rated 5–20 gal, but hygger makes it for tanks up to 23.6 in long and 9.8 to 15.7 in tall: the 20 gallon long is 30¼ in long and the 20 gallon high 24¼ in long and 16¾ in tall.
- hygger Cleanness Hang On Filter 5.5W: Rated 10–20 gal, but hygger makes it for rimless tanks only, and the 20 gallon long and the 20 gallon high we list have frames.
- Aqueon SmartClean Power Filter 30–50 gal: Rated 30–50 gal: built for bigger tanks than 20 gallons.
- hygger Hang-on-back Canister Filter 8W: Rated 40–60 gal: built for bigger tanks than 20 gallons.
- EHEIM professionel 4+ 250 (2271): Rated 31–65 gal: built for bigger tanks than 20 gallons.
- EHEIM classic 250 (2213): Rated 21–66 gal: built for bigger tanks than 20 gallons.
- Fluval 307: Rated 40–70 gal: built for bigger tanks than 20 gallons.
- Fluval AC70: Rated 40–70 gal: built for bigger tanks than 20 gallons.
- Aqueon QuietFlow Canister Filter 300: Rated 55–75 gal: built for bigger tanks than 20 gallons.
- Aqueon SmartClean Power Filter 50–90 gal: Rated 50–90 gal: built for bigger tanks than 20 gallons.
- EHEIM classic 350 (2215): Rated 31–92 gal: built for bigger tanks than 20 gallons.
- EHEIM professionel 4+ 350 (2273): Rated 47–92 gal: built for bigger tanks than 20 gallons.
- Fluval 407: Rated 50–100 gal: built for bigger tanks than 20 gallons.
- Fluval AC110: Rated 60–110 gal: built for bigger tanks than 20 gallons.
- hygger Biochemical Sponge Filter, Large: Rated 55–125 gal: built for bigger tanks than 20 gallons.
- Aqueon QuietFlow Canister Filter 400: Rated 100–150 gal: built for bigger tanks than 20 gallons.
- EHEIM professionel 4+ 600 (2275): Rated 63–158 gal: built for bigger tanks than 20 gallons.
- EHEIM classic 600 (2217): Rated 47–159 gal: built for bigger tanks than 20 gallons.
- Aquarium Co-Op Easy Flow Sponge Filter, Nano: Listed from 5 gal with no top limit, so we list it only up to 3 times that, 15 gallons.
- Tetra Whisper IQ 20: Its maker gives no tank size, so we can’t say it suits 20 gallons.
- Tetra Whisper IQ 45: Its maker gives no tank size, so we can’t say it suits 20 gallons.
Before you choose
A rating covers the water, not the space: measure behind the tank for a hang-on-back filter, and the cabinet height for a canister. Compare the filter types, or plan the whole tank’s equipment.
Tank pages: 20 gallon long · 20 gallon high · Heaters for a 20 gallon tank →