Seachem's Discus Buffer

Years ago I used Discus buffer (tap water ph 8.6), It seemed to work fairly well but was extremely hard to regulate, and every time I missed a water change, I had to re-think how much to add etc. It really was a hassle, because it lacks long term stability. As a summary, I would say that it does work, but you will have to be on top of your game at all times or you will see swings. I also ran peat in my filters which helped with the stability issue somewhat, but didn't allow me much of a break. In looking back from now, I think my fish would have been better off at 8.6 than the swings I put them through. But of course they weren't discus either.

R/O water should do the trick, at least as far as removing buffering agents is concerned. Do you have suspicious gravel or decorations that might be leaching buffers into the water?

Still, even when using R/O water you can't use it 100% and need to add back trace elements and buffers. The Seachem product works well for the buffering, but if you are trying to use it as a softener it won't work and will contribute to the phosphate problems you mentioned.

What kind of water changes are you doing, what are your tapwater parameters, etc.?

Harry, make note that I'm not the original poster, but...what do you think about the various Seachem Trace products?

I use their cichlid salts (for Rift Lake cichlids) with great success. For the rest of my tanks, I just use the Nutrafin mineral blocks by Hagen, because my tapwater is very soft and needs buffering and minerals.