i use bleach to clean my tank tools so this is really good to know!!! also makes me sad, tho, cuz my city is going to start adding sodium hydroxide to our water supply in a year or so. boooDavid,
I had a similar experience about three years ago. I was watching my fish one day and they all seemed perfectly alright when one of them suddenly darted across the tank and ran into the glass. This stunned the fish and it sank to the bottom. Never had this happen before. Then within a hour all of the fish were doing the same thing. I called Kenny (the fish were purchased from him). He told me that it was probably something in the water and asked me what I had done before this started. The only thing I could think of was the fact that I had changed the mechanical filters the day before. Within three hours of this first starting, all of the fish had died.
I wanted to know what caused this so I began to investigate. What I discovered might help others. The filters were the pleated canister type that I had been using for more than two years. I removed them once a month and cleaned them in a weak mixture of Clorox bleach and water. Then I rinsed them three times before allowing them to dry. On the third rinse I always used Prime to neutralize any residue of chlorine. Been doing this for several years without a problem. Then I looked at the fine print on the bottle of bleach and determined that it had sodium hydroxide in it. This was a brand new bottle that I had just used for the first time. I looked at the old bottle of Clorox bleach and discovered that it did NOT have sodium hydroxide in it. I was really PO'd. Clorox started putting in sodium hydroxide and did not label the bottle any different except in the fine print.
Then I found out that sodium hydroxide is a highly caustic substance and is used in the manufacture of many types of soap. I also learned that a simple test could determine if sodium hydroxide was present. Place a small sample in a glass jar and shake. If there is NO sodium hydroxide in the bleach the resulting bubbles will dissipate very quickly. Now I test every single bottle before using bleach.
Hope this helps someone else so that they don't have to go thru what I did.
Paul