Try wetwebmedia. Bob Fenner was the one who talked me into it, after coming by and looking at my tank.

Pros: The water is crystal clear. I mean GIN clear.

Cons: The units are pretty much all carp. If you do a search, you will see that the average life expectancy is about 12-18 months. So, buy a cheap one

They are brutal on your plastic equipment. However, my acrylic Ace-built skimmer seems to have handled it fine. You DO need a skimmer or other device to react it to your water.

You HAVE to have an ORP controller. Not just a probe, you need to be able to shut it off. Either that, or undersize your unit to be safe. It is toxic if the concentration gets too high.