Originally Posted by
TexMoHoosier
I've had planted tanks for a number of years and started with discus about 6 months ago in a high tech planted tank. If you keep your params stable and you are very capable of keeping a planted tank, the discus are actually the easy part, but that's easier said than done. When you're talking about discus in planted tanks, you have to be considering adults only, so buy the biggest discus you can afford. Don't expect any more growth after you add them to your planted set up. As far as water changes go, I use the EI method and do a 50% water change/gravel vac once per week and usually 1-2 25-50% change throughout the week. I do not believe that the Walstad method will work with discus in a 90 gallon, even if you only had a pair of discus and no other fish. Without large and frequent water changes, I think you'll probably run into more water quality/algae issues with a low tech system because of all of the excess nutrients and dissolved organic compounds. Discus eat a ton and produce a lot of waste. You will probably need to reduce the bio load you have right now to a few dither fish and scavengers and maybe 7 or 8 discus. In general, you'll battle 2 things with discus waste in a planted tank: 1) dissolved organic compounds from decaying protein (hence my extra 2 25-50% WC's) and 2) food debris/detritus on everything. Notice I did not say nitrates and phosphates. People on SD will tell you that less nitrates are better, but that only applies when the nitrates are from fish waste/decaying food (most people don't realize what they're doing is using nitrates as an indicator of dissolved organics, which are the real culprit, you could actually dose nitrates up to about 40 ppm and have no ill effects on your discus). You'll probably dose more nitrates and phosphates along with trace elements, although you'll modify the amount of nitrates you add since discus are heavy protein eaters.
So, long story short, I recommend learning all you can about EI, CO2 as a limiting nutrient and keeping a planted tank (besides using the Walstad method), get your tank and new method stabilized, and go with large/adult discus.