Frankie,

If the pH is stable in the tank then you should not be worried about it. How fast is the pH dropping? Did you check every 30 mins or what? If the driftwood is new then yeah it will contribute alot to the low pH. In case if u wanna bring the pH up, you can use a cheaper alternative other then using the pH Up from the lfs. Just get some corals and put inside the filter or in the tank itself. This will bring the pH up but you should monitor the pH of the tank to make sure the pH is ok. Make sure that the pH is lowered down/up slowly to avoid ph shock to the fish!

How long has your tank been up? It takes a few months for the bacteria to populate in the filter to take care of the waste effectively. If your filter is using the good sponge like those from hagen's fluval filter, you will find that the sponge will turn pink after a few months which is a good sign.

Nowadays captive bred discus are much hardier compared to those caught from the wild. The tap water in Kl/PJ is good enough for the discus. At first when I first keep the discus I was also very concern bout the water quality and did lots of checking and conditioning. Now.... after 10+ years keeping discus, i found the tap water (declorinated of cos) is just fine for them. They grow and they breed as well.

my 2 cents,
Joo