The gentlest: sponge filters
Air-driven, so the flow is the gentlest you can give a betta, with nothing to catch its fins. Each runs from an air pump, airline and check valve, sold separately.
| Model | Rated for | Moves the water | Room it needs |
|---|---|---|---|
| hygger Biochemical Sponge Filter, Small Sponge · sized for 5 gal and 10 gal | 5–20 gal | Not published | 2.9 × 2.9 × 4.4 in, inside the tank |
| hygger Double Biochemical Sponge Filter, Small Sponge · sized for 10 gal | 10–40 gal | Not published | Not published |
| Aquarium Co-Op Easy Flow Sponge Filter, Nano Sponge · sized for 5 gal and 10 gal | 5 gal and up | Not published | Not published |
| Aquarium Co-Op Easy Flow Sponge Filter, Small Sponge · sized for 10 gal | 10 gal and up | Not published | Not published |
With a flow control to turn down
Their makers name a flow control: turn it down so the betta isn’t pushed around.
| Model | Rated for | Moves the water | Room it needs |
|---|---|---|---|
| hygger Hang-on-back Canister Filter 5W Hang-on-back · sized for 5 gal and 10 gal | Up to 10 gal | 15.8× an hour in 5 gal, 7.9× an hour in 10 gal (79 GPH at most) | Not published |
| EHEIM LiBERTY 75 (2040) Hang-on-back · sized for 10 gal | Up to 19.8 gal | 10× an hour in 10 gal (100 GPH at most) | 5.3 in deep, behind the tank |
| Aqueon SmartClean Power Filter 10–20 gal Hang-on-back · sized for 10 gal | 10–20 gal | Not published | Not published |
| Fluval AC20 Hang-on-back · sized for 5 gal and 10 gal | 5–20 gal | 20× an hour in 5 gal, 10× an hour in 10 gal (100 GPH at most) | 4.4 in deep, behind the tank |
| hygger Hang-on-back Canister Filter 6W Hang-on-back · sized for 10 gal | 10–20 gal | 10× an hour in 10 gal (100 GPH at most) | Not published |
| Marineland Penguin PRO 125 Hang-on-back · sized for 10 gal | Up to 20 gal | 12.5× an hour in 10 gal (125 GPH at most) | Not published |
| Fluval AC30 Hang-on-back · sized for 10 gal | 10–30 gal | 15× an hour in 10 gal (150 GPH at most) | 4.4 in deep, behind the tank |
| Marineland Penguin PRO 175 Hang-on-back · sized for 10 gal | Up to 30 gal | 17.5× an hour in 10 gal (175 GPH at most) | Not published |
No flow control named
Their makers name no flow control. If the betta struggles against the current, slow the outflow with a sponge over it.
| Model | Rated for | Moves the water | Room it needs |
|---|---|---|---|
| Aqueon QuietFlow Internal Power Filter up to 5 gal Internal · sized for 5 gal | Up to 5 gal | 7× an hour in 5 gal (35 GPH at most) | 3 × 3 × 6 in, inside the tank |
| hygger AquaFall Aquarium Filter, S Hang-on-back · sized for 10 gal | 7–10 gal | 16× an hour in 10 gal (160 GPH at most) | 3 in deep, behind the tank |
| Aqueon QuietFlow Internal Power Filter 5–15 gal Internal · sized for 5 gal and 10 gal | 5–15 gal | 15× an hour in 5 gal, 7.5× an hour in 10 gal (75 GPH at most) | 4.25 × 3.5 × 6.25 in, inside the tank |
| Fluval U1 Internal · sized for 5 gal and 10 gal | Up to 15 gal | 13× an hour in 5 gal, 6.5× an hour in 10 gal (65 GPH pump rating) | 4 × 3 × 6 in, inside the tank |
| Aqueon PRO QuietFlow Power Filter 10 Hang-on-back · sized for 10 gal | Up to 20 gal | Not published | 3.8 in deep, behind the tank |
| Aqueon QuietFlow LED PRO 10 Hang-on-back · sized for 10 gal | Up to 20 gal | Not published | 3.625 in deep, behind the tank |
| hygger Backpack Aquarium Filter 6W Hang-on-back · sized for 5 gal and 10 gal | 5–20 gal | 26.4× an hour in 5 gal, 13.2× an hour in 10 gal (132 GPH at most) | 3.5 in deep, behind the tank |
| Aqueon PRO QuietFlow Power Filter 20 Hang-on-back · sized for 10 gal | Up to 30 gal | Not published | 4.25 in deep, behind the tank |
| Aqueon QuietFlow LED PRO 20 Hang-on-back · sized for 10 gal | Up to 30 gal | Not published | 4.25 in deep, behind the tank |
| Fluval 107 Canister · sized for 10 gal | 10–30 gal | 9.5× an hour in 10 gal (95 GPH through the filter) | 13.7 in tall, in the cabinet |
| Fluval C2 Hang-on-back · sized for 10 gal | Up to 30 gal | 11.9× an hour in 10 gal (119 GPH through the filter) | 4.7 in deep, behind the tank |
| Fluval U2 Internal · sized for 10 gal | Up to 30 gal | 10.5× an hour in 10 gal (105 GPH pump rating) | 8 × 3.5 × 4 in, inside the tank |
| Marineland Magniflow 160 Canister · sized for 10 gal | Up to 30 gal | 16× an hour in 10 gal (160 GPH at most) | Not published |
Before you choose
A betta pushed around by the current hides, clamps its fins and may stop eating. Turnover here is the maker’s figure for a clean filter at full flow; a filter that turns the water over many times an hour suits a betta only turned down. Betta care · How to read flow ratings.
A sponge filter runs from an air pump. Aquarium Co-Op Battery Backup Air Pump, Single Outlet and Aquarium Co-Op Battery Backup Air Pump, Dual Outlet run from USB and switch to their own battery when the power goes out, so the sponge keeps the tank’s bacteria alive through an outage. Aquarium Co-Op gives its current pumps about 20 hours on a full charge, or 40 hours or more in power-save mode, which runs the air 15 seconds on and 15 off. Setting up an air pump and sponge filter · Power outage plan.