I wasn't really too worried about my fish. I was more concerned if there where any long term affects that may occur. If it fixes my leak I wouldn't care if all the fish float : ) Keeping the water is much more important.
I spoke to a AquaBlok sales guy (real nice guy) but didn't get a price quote so you may be correct on the high price. He did tell me that the price was comparable to bentonite. Good luck and I look forward to your results......if I can wait that long before buying some myself.
