The Acid Test

Hard to believe that it will soon be three years since we first installed our BiUbe aquarium. During those intervening years, we've added to the shoal of cherry barbs to replace some that died, and they've been pretty successful in adding to their shoal themselves, too. In fact since that first spate of fry, we've had two more separate birthing occasions, so it's now entirely possible that we're on our third generation of fish bred solely in our tank.

We branched out into ocellated barbs about 18 months ago too, just for a bit of variety, but as yet there's no sign of them breeding. We're not even sure if there's a gender mix among those five fish to be honest.

Anyway for the whole of those three years I've kept up with my regular water tests - ammonium, nitrite, nitrate and pH - and on those rare occasions when anything has appeared to be going awry in the water quality department, I've been able to address the issue fairly quickly. But among all those tests one - the pH test - has never varied more than 0.5pH from neutral. Until about a month ago when, for the first time ever, the test came out something other than green. It was yellow - the water had become very slightly acidic.

I have no idea why; we haven't changed our routine at all. Not the food, or the water treatment, or the frequency of filter changes. If anything the gravel bed was cleaner than it has sometimes been, and stock levels hadn't changed since those ocellated barbs were introduced, so I was at a loss to explain it. However, since barbs like their water somewhere in the range pH6.0 - 8.0, I wasn't worried. Until, that is, I did another test last Sunday. For one reason or another I hadn't tested the water for four weeks (I used to do the tests every week but when the results don't change from one week to the next for over two years, it's easy to relax the schedule a bit) and on Sunday the pH test came up orange.

That's pH 5.5. Yikes.

Fish didn't seem too bothered. A little more active, if anything, which apparently is normal at lower pH, but not distressed. And another tiny Kevin appeared a week or so back, so it can't be THAT bad. Can it?

Anyway after some rapid Internet research I decided ocean rock was the way forward. Our water is so soft that it doesn't register on a KH test at all, so attempting to correct the pH with chemicals would have been tricky (and I don't like that approach anyway). So off I went in search of a chunk of ocean rock, boiled it and baked it for the prescribed times, let it cool and with some trepidation, dropped it in.

A day later the pH test colour had relaxed from orange to yellow, and 24 hours after that it was lime green, so we're at something like pH 6.5-7.0 now, and it's taken two days to make that change. Which is good, because while fish can adapt well to different pH levels, what they don't like is RAPID changes in pH. I'll be doing another test tomorrow to check the tank hasn't pivoted over to alkalinity, but with luck I'll be able to leave the rock in there permanently. The extra minerals will act as an acidity buffer and help to keep things on an even keel from now on.