Sounds like a stupid question to ask in my first post to this forum, but I am serious.
I had 3 successful (by my own definition) planted discus tanks before and am in the process of redoing one. Hardware: 850l (225g) tank, Eheim 2080 canister, 300W heater, surface skimmer + bottom drain, CO2 injection with pH-controller, 2 Maxspect Razor LED lights. Substrate: 20 kg laterite gravel + 80kg Seachem black fluorite + rocks and driftwood. Water: RO/DI + Seachem equilibrium and bicarb buffer plus various fertilizers as determined by water testing (N, P, K, Fe, flourish, etc).
My fish load is not very heavy, as I am more a sucker for plants. There are a handful of discus (occasionally more), a large cleaning crew (SAEs, ottos, whiptails, cories, RCS, snails) and small peaceful companions (50 cardinals, other tetras, pencils, hatchets etc.).
I remember a quote of Amano 'Happy plants, happy fish'. The lemon tetras, cories and RCS breed, and the discus have spawned many times. Although I then remove the pair to a separate tank, and yes that is bb.
My biggest problem has been bullying among the discus. Sometime I separated the bully, sometimes the victim, but neither is ideal. Perhaps I would need to keep more of them, and/or raise them together from young?
My pH is simply what I set on the controller, but I keep it at pH=6.7; KH is what I put in, but I keep it at 3 to get ca 20ppm CO2. Temp=28C, GH=3, NO3=8ppm, PO3=1ppm, Fe=1ppm, K=10ppm, (or there about). The plants thrive, bubble off plenty of oxygen and I need to remove a bucket full every week (and with it nutrients).
So water change or not, if I wouldn't supply NO3 and PO4, there would hardly be any in the tank.
Now, I do a 25% water change every week, because that is what one does, but I wonder whether that could be cut down.
So my question is serious, do I really need to change the water so often? And do I need to vacuum the bottom? The latter is complicated as it is covered with hairgrass, tenellus and small crypts.
Re: Why changing the water and vacuuming the gravel?
I can't answer your question, but would love to know how you keep a 225G tank warm enough for discus with just 300W? Maybe the room is quite warm to begin with?
Re: Why changing the water and vacuuming the gravel?
Only one side of the tank is visible, the other 3 sided are covered inside by 5cm Styrofoam into which I heat molded some interesting structures, covered with pond sealer and pulverized scoria. It looks like a rock wall covered with plants. The tank is built into a floor to ceiling closed column, with only one side facing the open room. I was surprised too, but the 300W Eheim is plenty to keep it warm. Another benefit is that it is whisper quiet.
Re: Why changing the water and vacuuming the gravel?
Thanks jeep, that link is informative. I am also worried about bioload, hence I keep low stock, a big cleaning crew, feed relative little and ensure that very little hits the ground. My motto is: A hungry fish is a good fish. I pay with slow growth obviously, but that doesn't particularly border me, patience is a virtue.
You guys convinced me not to reduce my water changes any further, evan though I wouldn't run into a nitrate problem. Thanks. I will also continue vaccuming my plants and removing every sick leave and not trying to fix what's not broken.