I woke up this morning looked in my tank to see my two pictus cats floating around upside down dead i don't know why im staaying in a caravan in my garden at the moment cuz we got our floorboards polished and theres chemicals n stuff but they were no where near the chemicals i dont have any testing equipment i have asked santa so fingers crossed but i dont think ammonia is the problem cuz iv got a filter full of eheim bio media thats been in there for months any one got any ideas.