Discus water changes.

Discus like very clean water and are sensitive to nitrates. You want to keep the nitrates below 10 ppm at all times (preferably lower). I change 80% twice a week and my discus do very well. There is very conflicting information on discus and the best I can say is to talk to many people who are successful at keeping discus and find the method that works best for you. You may not want to do as many water changes as I do so find a method that you can live with. Just beware of those that tell you that their way is the only way.

I would agree with Deb2 that larger water changes have worked better for me. I tend to do 50% water changes twice a week, if my schedule permits it.

I change 50% once a week on my tank. I do it every Saturday morning. The discus are doing really well. If I had more time I would do the same amount twice a week, but I have three small kids so I'm kind of tied up during the week.

According to Jack Watley, who has a Q/A column in the TFH Magazine, he suggests 30 to 40% water change 3 to 4 times a week. He said that if the fish have got used to large water change, a 50% daily water change is not excessive. So according to Jack, discus is best kept in an open system in which the water change turn over rate is several times a week. This is why I don't keep discus because there is too much work.

It's going to depend also on stocking levels, whether the tank is planted, how close you can get your change water parameters to that in the aquarium, what filtration you're using, I'd have thought.

Stocking levels do make a difference but discus are sensitive to nitrates and the only way to get rid of nitrates is through water changes, plants make only a minute contribution to nitrate removal. Actually more plants use ammonia than nitrates.