not sure what is in it but silver is what I want. This works well in a 500 gal hot tub so i only use a tablespoon of diclor when i exit the tub.

I always use these or similar

These really seems to work, but I have gotten a cople that have had loose particles floating around in the box. One of these turned my water cloudy the first day I put it in. The others have work great!

Been using spa frog mineral sticks for years! You can really tell the difference when one runs out and you replace- water feels so much nicer!

This is an extra filter for your filters. It's awesome for families. It slides inside the larger filter and gets replaced about every 3 months. This makes a big impact on keeping our tub balanced. Especially when we have extra neighbors kids & friends over. We cut down big time on all the other cleaning and balancing products. It's kinda pricey up front but saves us in a lot of products in the end.

great product for the price