Generally, these Cal-hypo tablets are useless junk. The plastic-wrapped ones may be better--I don't know.

But I have found a use (finally) for the old Duration tabs I had hanging around: Keeping algae out of drop-insteps.

I have wedding-cake steps and I can always see inside them and see algae forming, no matter how high my FC level.

So I put 3 Duration tabs inside the steps and VOILA! no more algae!

I put on a neoprene glove so I don't have to touch them when they are wet. I can just get the steps away far enough to get my arm in and drop a tablet near the outside of the steps. I get 3 in this way and haven't had algae in them or on the vinyl mat under them since.

So I guess they ARE good for something after all!