Spaguard Spa Calcium Increaser Spaguard Spa Calcium Hardness Increaser - 12

It was exactly what we were purchasing at our local pool store for a lot less money.

Last a long time, and does its job well.

This product does the trick for hot tub. Does need to be dissolved prior to using in tub, and I feel I need to use more product than the ones I have used already in liquid form. Price point is decent, as the liquid form product tends to cost more, but maybe a slight tradeoff for how much quicker I've gone through the granules. Why 4 of 5 stars

I am very fussy about my hot tub. This is very easy to use.

The SpaGuard series of products are good and easy to use. The Calcium Hardness increaser is no exception. Turn spa on, dump it in, and it raises the hardness in your water. Easy peasy.In my experience, the problem comes if you've decided to use the SpaSentry product to help keep your pH steady for longer. An effect of using it is that it removes calcium from your water. So it actually reduces the hardness in your water. Well, if you follow the directions on the Calcium Hardness increaser, when the hardness reading is below 150ppm, you add the increaser. Which the Spa Sentry product, already in your water, precipitates out (as those white clumps you see in water). This fills your filter which then must be cleaned. And it drops the hardness again. Endless cycle...This product does what it's supposed to well. Its the SpaSentry that causes the problem. Your mileage may vary, but I'm staying away from the SpaSentry product next refill and manage pH the old-fashioned way of using pH increaser/decreaser as needed.