Cleaning the aquarium is an essential part of life for your fish. Cleaning the tank isn't that neccessary if you have a filter but weekly scrubs and monthly cleans of the tank can help you fish live a long and happy life. But the right klind of scrubbing tool and before you do scrub, take your fish out of the tank and clear out any of the alge or ich you can get before you place your fish back in. If needed, dump out the water and replace it with new water. Be sure to use water conditioner/de-chlorinate and check the temperature before you place your fish back in the tank. Always make sure it is throughly cleaned and scrubbed before placing new water in for it is dangerous to have bubbles in a fish tank unless it comes from the filter making bubbles like it is supposed too.