Filters all work about the same as far a mixing oxygen into the tank water and allowing carbon dioxide to escape (gas exchange). They should have a minimum gph
(gallon per hour) rating of roughly 4 times the volume of the tank in gallons. You simply need to follow one rule. A small tank up to 30 gallons should get a 50 percent water change twice weekly. A tank larger than this, should get the 50 percent water change weekly. Do this faithfully and the water chemistry will be right for your fish and plants.