How we think about filters
Three variables dominate the decision:
- Tank size. Flow rate should turn over the tank volume 4–6× per hour for planted setups. Less and you get dead spots; more and you blow plants around.
- Livestock. Shrimp and fry need sponge or sponge-guarded intakes. Large fish need more mechanical filtration.
- Planting density. Heavily planted tanks do a lot of biological filtration themselves, so mechanical filtration matters more than bio media volume for these.
Canisters are quieter and hold more media but cost more. HOB filters are cheaper, modular, and easier to maintain. Sponge filters are the shrimp-tank default and the cheapest option.