by Jack MacDowall

Created on: January 17, 2007   Last Updated: April 16, 2007

A little preventative maintenance on a fish tank can go a long way towards keeping the fish healthy and keeping your tank looking good. Keep in mind that you need to disturb the fish and the good bacteria as little as possible. Harming either is going to do more damage than good. If you kill your bacteria, you're going to have cloudy water and lose your biological filtering capability. If you kill your fish, what's the point of a crystal clear tank?

Say I have a 20 gallon tank. It's very beneficial to replace 20% of the water every two weeks. I use 5 gallon utility buckets, like the kind that contractors buy Spackle in. Having done some sheet-rocking myself, I have lots of these buckets. Fill one bucket with lukewarm water and treat it for chlorine with Stress Coat or similar or put an air stone in it for 24 hours.

When you're ready to clean your tank, turn off all the lights and pumps and unplug everything.

Start by cleaning the sides. Clean the outside with a moist cloth. Avoid the Windex. Chlorine, remember? Clean the inside of the glass with a razor or one of the cleaning sponges from the pet store. Don't use a sponge from the housecleaning bucket. The residues from the cleaning products on it will poison your fish.

Now, vacuum the gravel, siphoning off about 20% of the water in the tank. I use a 3" tube that connects to a tube to vacuum my gravel. If you have an under gravel filter, leave about a 1/3 of the gravel undisturbed. You don't want to suck all the bacteria out of the gravel, just remove the big chunks.

If you're squeamish about sucking the hose to start the siphon, one of the venturi type siphons will work. I don't like that kind because I use the water I siphon out of the tank to rinse my filter bags. The venturi siphons put a lot of tap water in the bucket, too. Now your old tank water has chlorine in it and you risk poisoning your filter bacteria in the old water. The best compromise is to use a little trick with one of the standard siphon tubes, simply put the tube in the tank and allow it to fill up with water. Then plug the end that will go into the bucket with your thumb. Bring it to the bucket and let go...instant siphon!

Next step is to rinse filter in old water. Take the filter bag out of the filter and give it a good swishing about. Don't run it under the tap. The tap water will be the wrong temperature and will contain that nasty chlorine. The water you siphoned out of the tank is perfect for rinsing. You don't really want to clean the filter, just get out the big chunks so that the water can pass freely through the filter again. You don't want to wash away too much bacteria, that's the real filter!

Check your hoses and tubes for clogs and kinks. Rinse out any clogs in fresh water.

Now, put everything back together and slowly pour the treated water into the tank. Don't forget to prime your filter before you plug it in.

As for changing the charcoal and the filter bags, I usually do it about every three or four months. After a while there's just too much sludge. Caution. Don't clean the tank AND change the filters at the same time. You'll end up with a tank that needs to be cycled and your water will be cloudy for 3 weeks. Change the filter some month instead of cleaning the tank and vacuuming the gravel. My filter box is big enough that I can change the filter bag, put new charcoal in the bag and put the old bag in the filter box, too. The water passes through the old bag, then the new bag and hopefully carries the bacteria colony into the new filter media.

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