The easiest way to keep your aquarium clean is to use the right size filter. And you can choose the correct filter by matching its flow rate to the size of your tank.
For example, the water in the aquarium needs to pass through the filter four times per hour. If you have a twenty-gallon tank, you’ll want a flow rate of at least 80 gallons per hour, or four times twenty. But if you have a crowded tank, extra equipment like a protein skimmer, or fish that make a lot of mess, you’ll be better off with a bigger filter. In that case, get one rated for 120gph to be sure the water stays clean.
Also, there’s no harm in choosing a filtration system with a higher flow rate than you need now. This is especially true if you invest in a system with adjustable flow. The best filters for fish tanks are matched to the needs of their inhabitants. And those inhabitants may grow in size or number over time.
Now, there is one mistake that a lot of aquarium owners make in their zeal to clean the filter. If it seems like algae builds up too quickly inside your tank and the water yellows too fast, you might be doing the same thing.
If your water gets dirty too fast, try this tip
When you clean the filter, don’t be too anxious to scrub every detail. In other words, don’t wash every part every week. Instead, pull out the sponge and rinse it in dirty tank water instead of tap water. Really. That will keep the beneficial bacteria safe. Just scoop out a little water from the aquarium, put it in a bowl, and use that to squeeze out the debris.
Do the same for the carbon cartridge if you need to remove excess gunk. But plan on replacing the carbon every month to month and a half. This is important because the carbon becomes saturated with toxins, then starts to leach them back into the water.
Finally, don’t change the sponge and the carbon cartridges at the same time. The same goes for any other layers of filtration. Replace them a couple of weeks apart. That space of time allows the bacteria colonies to stay strong. And healthy bacteria consume the nitrites and nitrates that can poison your fish. Plus, your tank stays cleaner.