We have a 29 gallon fish tank with 3 snails, 3 shrimp and 3 catfish. We also have moon fish that I read like to eat algae. We have had the tank a couple of weeks and it looks really clean. I also read I should do a partial water change every two weeks. With all those bottom feeders, I was wondering how often I should clean my tank?
How often you need to clean the gravel and the filter material is dependent on the bioload of your tank.
The bioload is the number of animals living in your tank plus the amount of food you feed your animals living in the tank. And the plants will add to this too when leaves die and decompose.
The gravel will accumulate waste over time so you need to clean it at regular intervals. And if you feed your fish a moderate amount each day you will need to clean the gravel once a month.
The cleaning is best done with an aquarium vacuum and you need to push this all the way down until it meets the glass bottom of the tank. You will see when the water gets clear at each point you vacuum in your tank (you do this in a grid pattern in the gravel of your tank).
You need to take a look at the filter media each time you clean the tank and if this starts to get clogged up you use some of the water from your tank to clean it (it is important to use water from your tank when you do this to keep the good bacteria alive).
You normally do not need to clean the filter media more than every 2-3 months, but again, this is dependent of the bioload in your tank.
It is better to change a small amount of water each week than it is to change a lot when you clean the tank. Water changes are mostly to keep the nitrate level down, but it will lower other waste product levels too.
Partial water changes are enough if your water quality is good. Substrate cleaning and glass cleaning are not necessary if your tank is doing well. It would be only for cosmetic reasons, for example if the glass becomes cloudy you can brush it off to see better inside.
The substrate and water and everything becomes "alive" and rich as the tank ages, with a kind of "biofilm" on the surface, on the bottom, the glass and everywhere else, that's a good thing. If you "sterilize" it too often, you will lose your bacterial cycle. Don't really need to clean the filter cartridges either since a lot of good bacteria lives there. Most "algae" and microscopic life is good for your tank. Green algae spots on the glass mean good. Big volume of slimy squishy green stuff would be too much, for example if you leave your tank in the sun. As well if your stuff is covered in brown algae, it means something is wrong. In such a case, just cleaning it is not enough, you'd need to find the cause.
I've had a few tanks for many years. I change 25% of the water every few days, sometimes one week. Follow your feeling, and if you notice the water becomes cloudy or dirty, do a change today. 2 weeks is a bit long for me, I'm not THAT busy that I need to let it wait for so long.
Basically the snails, shrimps and live plants are your cleaning crew. Keep the water good and the rest will follow.