Good or bad with low PH in discus tank?

[d4discus]

I used rain water stored in water tank for my discus tank. The tank water PH is 6.93 and the PH on my discus tank is 6.15 at the moment. The discus tank mate are 3 gourami and 8 rummy nose tetra.

My question is how low the PH can be before the discus and the tank mate will start having problem? :?:

[FishLover]

Discus like low pH. It should not have any problem in the mid 5s, actually, it loves that kind of pH. The problem is you may have a hard time keep the pH steady when it goes lower than 6 because you may have a pH crash. That could kill all your fish in a very short period. Your filter will have some problems too if it goes into lower 5's. It will not function well at lower 5's.

[d4discus]

Thanks. I don't intend to alter the pH using chemical or some sort. My approach will make more frequent water changes. Any suggestions how to raise the pH to the mids 6 ?

[FishLover]

Some crushed shells will do the trick. The problem is how to control it to the mid 6's. Most likely, the crushed shells will try to buffer your pH to 7's. You will have to try out the exact amount of shells. Don't try to do that with the discus in the tank, the pH swings are not good for them.

Personally, I don't see why you want to increase it. If you are going to do lots of water changes, I would not bother to change the pH at all. Just take what you have, which is perfect for discus. I wish I had your water.