water buffer

[Olly]

The water coming out of the tap at my place is very variable in pH ranging from 6 to 7 although usually nearer 6

Im looking for a rock or substrate that I can put in my tank to buffer the water at 6.5 for my discus. when the pH out of the tap is high my discus suffer but when its at 6 the guppies look terrible

What should I do? the discus seem to be happy in the range of pH 6.2-6.8 and the guppies at anything higher than 6.3

[Charlie]

I find that Peat keeps the pH at arround 6.5-7

I would put your discus health before your guppys, guppys are hardy and cheap to replace. Discus how ever :bounce: up and down like a yoyo.

You want to keep the pH steady and even when doing water changes so there isnt to much of a shock.

Good Luck

[VinsonMassif]

Contrary to popular mythology fish are unable to read pH.

What they do respond to is osmolarity of the water. Also total dissolved solids (TDS). This is where monitoring of KH and GH would be practicable in attempting to keep stable water parameters.

One example of pH vs. osmolarity: CO2 lowers pH but does not change the osmolarity of the water.

[whetu]

Olly, does your water change if you leave it in a container to settle for a few hours? Sometimes just leaving it in a bucket (ideally with an airstone in it) can settle the pH so it is similar each time you piut it in the tank.

It might be worth giving it a try - at least by experimenting you might get some more clues about the cause of your pH swings.

Also, sometimes just leaving the tap to run for a while before drawing the water can settle the pH a bit. I was told (by my local water engineer) that water that has been sitting in concrete pipes will have a higher pH but after it has run for a few minutes you start getting fresh water from the mains and it might have a lower pH. I'm just repeating what he said so I cannot back it up... I think his logic may have some holes in it, so to speak :-?