I've been using sodium thiosulfate/sodium carbonate containing products to break the ammonia-chlorine bond. Plants love ammonia and I can't think of anything better for them. Never noticed any toxicity to fish in a well planted tank. This assumes a pH at or below 7.2 or so. I use AMQUEL only when ammonia-free water is required. Of course these products are about 1/10 th the cost of AMQUEL. Dave --