Having trouble getting CH up

[ptbrunet]

Hi, I need to raise my CH and it seems it's not going up as much as calculated. Is that to be expected? Below is the history.

4/10: CH 180 at Leslie's
4/20: CH 170 using TF100 kit
4/27: added 64 oz weight HTH Calcium Plus (CaCl), should add 29 CH
4/29: added another 64 oz, should add another 29 CH
5/5: CH 210 (expected about 230)

 

[JamesW]

128 oz of calcium chloride dihydrate will raise the calcium level by 44 ppm in 15,000 gallons. Starting at 170 ppm, you should get to 214 ppm, which is in line with what you are seeing.

You have chosen calcium chloride in pool calculator. However, it's unlikely that that's what you used.

Also, pool volumes and test results are rarely exactly accurate and you have to allow for some expected inaccuracy.

 

[ptbrunet]

Hi James, Thanks for responding. I just found the MSDS at
http://www.whatsinproducts.com//files/b ... 20PLUS.pdf
and I see it's only 90/95% CaCl so that would result in a little less of a rise but not as low as the 40 I observed. Anyway it looks like I can use the empirical evidence that I'll get a rise of 20 per 64 oz container. Now that I am at 210 I'll add 64oz at a time until I get to or above 250, hopefully just two more containers.

 

[JamesW]

Based on the MSDS, it does look like HTH Calcium Plus does contain anhydrous calcium chloride.

It shows that the percent could be as low as 90 %, which would raise the calcium hardness by about 52 ppm in 15,000 gallons. Therefore, you might expect to get to about 220 ppm, which is within the margin of error.