"Alkalinity" too high? What to do?

[zim64half]

Howdy.

I have a 72 gallon tank, which has 3 medium to small discus in it.

I have been doing water changes, and when I do, I am using my home's tap water.

My tap water is being treated by a home water softener, and also comes out with a high pH - around 7.8

I have been adding "discus buffer" to the water to bring it back to around 6.8 when I do a re-fill.

But even though I am able to get the pH to come down (I should probably get it to go lower too) I am not able to affect one reading on my water chemistry test strip. "Alkilinity" which is a different reading than the pH.

My alkalinity is always pegged at the high end of the chart - 300 ppm KH.

Is this stressing out my fish? If it is, how do I get it to come down?
(My fish are not exactly thriving. 2 look ok. The biggest one is growing slowly - the other isn't - and the 3rd looks beat up all the time.)

Also - is there a reasonable way to get the pH to come down, without spending $15 a bottle on discus buffer - which is only enough for about 2 water changes?

Thanks in advance!

-Zim

[samir]

you can use HCl or H3PO4

[mistakes r crucial]

Your KH level is not overly important as long as you are not trying to breed your fish. In fact, if they are young fish, you are better off with harder water as they need to take minerals out of the water for health and growth reasons. However, your water is getting to the liquid rock category and if it's that hard I wonder what your GH is? When you say water softener which type of cartridges does your water filter use? I'd be taking hardness readings (GH and Kh) straight out of the tap pre water filter and post and see what the difference is.

Many domestic strains today, so we read, thrive and breed in water that has a Ph of 7.5 and sometimes slightly above. I've always tried to leave water alone whenever possible but IME lower Ph values do have a lot of benefits such as bacterial and ammonia issues. To lower both the Ph and KH you can try peat but as your water is very hard to start with it may not work. If it doesn't you're left with the option of RO and that's about it.

As Samir said, you can alter your Ph with either Phosphoric or Hydrochloric Acid but never add either of them directly to a tank.
MAC