This last month we saw a discussion thread about checking test kit accuracy and a couple threads also came up recently about salinity/calibrating Refractometers.
Well, today I had an experience in that general category. I came to the realization that the Flatworm treatment chemical I have, has gone bad. I bought it about 5 years ago and, because it is very potent, I haven't used much of the original 52 grams. The original package probably had an expiration date, but it was discarded long ago when the chemical powder was transferred to a clear specimen cup and the drawer holding the empty package was cleaned out during a move.
Today I looked it up and discovered that this stuff expires after two years and additionally, it should not be exposed to light!

For months I had it sitting next to the tank near a window!

All of this explains why the two friends tanks I have recently treated for Flatworms, still have flatworms. To make matters worse, the chemical doesn't just go inert, it changes into something toxic that stresses the animals. A few coral and a few fish have been lost in those tanks.

I feel absolutely horrible. Any sympathy offered is appreciated, but mainly I want to share this experience so that you all may learn from my mistake of not keeping and checking the expiration date and not learning how to store the stuff.
What is this stuff? Prohibit brand Levamisole HCL(Hydrochloride), the active ingredient in Salifert Flatworm eXit. $25 of the 99% pure chemical treats 1000's of gallons. Flatworm eXit is $16 and treats only 300 gals. For anyone interested, a modified treatment method, a much easier method than Flatworm eXit, was discovered by an expert hobbyist friend and I've been using it ever since. The method is listed in the Reefkeeping Tips and copied here for convenience.
Aloha,
Mark

sad but wiser
