when and how much?!?!?

[RENEGADE]

ok i've heard so many numbers throw around: should i change my water every 1 or 2 weeks and 20%, 30%, 40%, 50% or 60% water change????!!!! my friend(who just got his tank 4 month ago) says 2 weeks 30% WC
BTW i have a BIO-FILTER® should i change that every 2 weeks?

[VoodooChild]

Is the Bio Filter Whisper's thing? If it's just a sponge you can just rinse it out in the bucket after you've taken the water from once a month or whenever you need it. If there's carbon in it then I'd just use all the cartridges you have left, one per two weeks, then find a suitable sized sponge and put that in there. I try and do 10-20% water changes once a week, but once every two weeks should be fine unless you have something large like an oscar. You're gonna hear a million different things in this hobby, so try not to get overwhelmed.:)

[JSchmidt]

If you invest in a nitrate test, if you don't already have one, you can change water on the basis of need, rather than on some arbitrary percentage. Keeping nitrate below 40 ppm should lead you to do enough water changes to keep your fish healthy.

Jim

[OrionGirl]

Jim's advice is right on, unless you have a planted tank. In my 40, I have never had detectable nitrates, because the plants suck them up quickly. Lacking a reliable method for determining toxin build up, I go for the next best thing--stability. If my changes are more than 10 days apart, my buffers start dropping and causing the pH to fluxuate. A 20-25% water change once a week prevents that.

The important thing is to determine how often the water should be changed to provide a stable environment with clean water.