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Your cart is empty.This product is used to increase the calcium hardness in spas and hot tubs with low levels of hardness. Low hardness levels will etch plaster and corrode equipment. Before adding this product, test the water with a calcium hardness test kit or ask your local spa dealer. The ideal hardness level is 200-400 ppm (parts per million). 1 ounce of product per 500 gallons increases hardness by about 10 ppm. 1. Determine amount of product to be added using a calcium hardness test kit. 2. Pour proper amount into spa or hot tub with equipment turned ON. 3. Run filter for 1-2 hours. 4. Water may be retested in 20 minutes.
Springtime
2025-08-09 12:23:04
Prefer this over the granular products. For some reason they don’t dissolve fully. This liquid is easier and works well.
Mark
2025-07-19 10:50:36
I’ve tried a lot of other Corine brands and this one is by far the best for value and functionality.
Christine Duncan
2025-06-19 12:04:28
Previously used the solid/granular type water hardener. This works much better for my hot tub and seems easier to keep my hardness balanced to an ideal range.
Old guy
2025-06-09 17:49:28
I drain and refill a 350-gallon hot tub a couple of times a year. Our well water has no minerals, so I add calcium. This does it, 1/3 to 1/2 bottle per.
Dylan Milroy
2025-05-16 10:53:41
Our water was pretty soft so it took a lot to get it to the correct levels but it got it there. Don't add all at once either put in the recommded amount and wait a couple hours to check and keep adding till you get there. It took about half a bottle for us to get to the correct level but thatll vary depending on your levels from the tap.
BJP
2025-05-12 14:00:20
This review is for the liquid form of the product, not the dry form that has so many bad reviews. Mine arrived in perfect shape. There are handy graduated lines on the side of the bottle showing ounce measurements, which makes it very easy to dose into the hot tub. Unlike the dry form, this goes into solution almost immediately when added to a tub with jets running, while I've seen the dry form take hours to dissolve. Add it to your tub at the amount recommended for your tub volume to reach the calcium hardness values you want. Very easy to use and effective.
Brian
2025-04-04 15:10:05
Works great
Allen Bizjak
2024-12-19 12:20:49
I have a hot tub and the water from my house is a little soft. I added some of this to increase water hardness to help maintain water quality/ clarity in my hot tub. Worked well.
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