Trebuchet

Thanks for your comments Alan and Warren. I had actually dissolved it in a cupful of water during water change and poured it direct into the filter container so that it would be force-dispersed into the tank. But i suspect that despite not using a large amount of the stuff, over 3-4 weeks it had a cumulative effect. I have now done 3 large-ish water changes, and the Phosphate levels are slowly coming down (now at 5 instead of 10). Going to persist with large water changes for a couple more weeks, and have tossed the pH Down in the trash. :facepalm:

I'm just putting this out there for all to take note of - I have been having problems with higher than usual pH problems in my community tank (Juwel 180l), which occasionally jumps from 7.0 to 7.4+ due to what i think may be the local Wellington water supply. After talking to a couple of staff members at LFS i thought i would try Aqua One pH Down - http://www.aquaone.net.nz/cart_product19299-1-2881.html?Title=92084%20AQUA%20ONE%20PH%20DOWN%20QUICK%20DROP%20100G Used it as directed after weekly water changes for the last 3 weeks, then started to lose fish last week at an alarming rate of one a day . Did a quick check of all the usual levels - pH was fine and sitting at 6.8/7.0, Nitrates and Nitrites were fine at 0 or close to it, Ammonia was fine at 0, but Phosphates were alarmingly high at 10 (3 months ago it was at 0). I tested my source tap water before and after adding Aqua Plus Water Conditioner and everything looked fine (pH a little high at 7.2 but basically ok, Phosphates at 0). HOWEVER..... when i tested a cupful of the conditioned water with a tiny bit of Aqua One pH Down added (1/4 of a scoopful using the scoop that comes in the container) the Phosphate level jumped through the roof to 10. The Phosphate spike may not be the cause of the fish deaths, but it seems a bit too coincidental that they only started to happen with introduction of the pH Down. I now have to slowly flush the Phosphate levels out by doing large water changes (about 40-50%) every 2 or 3 days, and hope like hell i don't lose any more of my little guys. So just be careful if anyone out there is using Aqua One pH Down or considering using it.