Pool Water Hardness

Jun 26, 2007

Could you tell me the best way to increase the water hardness? I have a guinite pool. Is there a cheaper way of raising the level with out buying it from the pool store?


In The Industry
Mar 29, 2007
Knippa, Texas
Please post a full set of test results, and tell us how they were obtained (pool store, your own test kit, type of test kit, etc.)

Calcium hardness or CH is what's important in a gunite pool. Its level should be 300 or so. CH is raised with calcium chloride (calcium hardness increaser) which is not at all expensive, even at a pool store.

You can figure out how much you need to add by consulting the pool calculator:

It's also linked from the forum homepage and lots of members have the link in their sigs.
Jun 26, 2007
You mentioned that even in the pool store the chemical, calcium chloride is inexpensive even at the pool store. I just spent 61 for a 45lb bucket. I was tols that I probably need more than that. My current Calcium Hardness level is 100.
Here are my numbers that I received from the pool store.
PH 7.6
Alk 60
Calcium HaRDNESS 100.

I was also told that my phospate levels were high. They told me that this is why I have had trouble getting my pool clear and free of algea. Any thoughts?
Many Thanks!


TFP Expert
Platinum Supporter
LifeTime Supporter
May 7, 2007
Silver Spring, MD
DowFlake, a brand of calcium chloride, often sold as an ice melter, tends to be around $35 for a 50 lb bag if you can find it locally. I have seen it for $45 with shipping on the Internet.

Just ignore everything they told you about phosphates. It is extremely unusual for the phosphate level to make any difference. Just maintain your FC at appropriate levels and you won't get algae.
Jun 26, 2007
Thanks! I will attempt to find it. I have a feeling I will have to buy it next winter for next season. I will try online for this year.
Are there any posting s on this site, or another that you are aware of that talk about the phosphates?
Tetra is another brand of calcium chloride that is sold in 50 lb bags that is suitable for pool use. It comes in both flake and pellet form. the Pellet form is anhydrous (without chemically bound water) so it is a bit more concentrated. The flake is the dihydrate form, same as the calcium hardness increaser sold in the pool stores.