Burnt finnage?

Ok, better get the health thread started with a problem I get
I hate moving large numbers of Angels around the fish house, I fill 3 buckets with water from their tank, put air stones in them & start catching fish to seperate colours or sizes etc, they can be in the buckets for 20mins or so with sizes from 5p to 50p bodysize, anything from 10 to 30 in a bucket. I then fill the new tank with some water from their old tank & top up with fresh water & a mature filter.
But when I catch the fish from the buckets they have some sort of fin burn around the edges, now my ph is about 6.4 and my water is very soft with a very low GH & KH, now is the fin damadge due to Ammonia burn? (but a low ph makes Ammonia less toxic), ph burn? (possably due to a ph crash) or just stress? I'm stumped, any ideas?
Lisa

Hi Lisa,

I suspect your problems may be caused by the airstones. Assuming you haven't used any chemical pH adjusters, the pH of aquarium water is governed by the interaction of the carbonate hardness (KH) and the amount of CO2 in the water.
At any given KH, the more CO2 in the water, the lower the pH will be.
For any given level of CO2, the lower the the KH the lower the pH will be.
Using aereation drives off the CO2, causing the pH to rise. a big airstone in a relatively small bucket could easily drive 90% of the CO2 out of solution, this would cause your pH to rise from 6.4 to 7.4. I don't know if you've tried, but try checking the pH of the water in the bucket after the fish have been there for 20 minutes.

When moving fish from one tank to another I simply use a plastic bag part filled with a few pints of water (I use 10" x 22" bags with at most about 4 pints of water). If moving from one tank to another at home I'd happily put 20-30 50p sized fish in one such bag, float on the destination tank for about 20 minutes and release. when taking fish to the shop I'd probably bag about half that number for 50p (body size excluding fins), for slight smaller (20p sized) fish I usually bag about 25-30 at a time. I don't have oxygen at home, so the bags are filled with atmospheric air, and by the time I get them to the shop some will have been in their bags for at least an hour. They then might float for an hour until I get chance to release them. Following this routine I've not noticed any fin burn, although the odd split fin from being captured isn't unusual.
My point is, with just 30 fish in couple of gallons of water, it shouldn't be necessary to have airstones running for that short period.

Wow, wow, wow..... never thought of the ph going up
Well I am glad to have learnt something new today & shows that I realy need to learn more about water.
By the way my water comes out of the tap at that ph , even Discus breed in my tap water
Lisa

even Discus breed in my tap water

I might come & visit you with a small tanker!

And I'm not on a meter , you get your tanker & I will start filling
Lisa