Adding Calcium hardness increaser raises pH?

[vitruvian]

Greetings!

I've been following the advice from TFP to maintain my pool for a few month now. It's been working great. The only parameter that's off is CH--it's been hovering around 240ppm or so.

In the attempt to raise CH, I purchased CH increaser here Amazon.com (it says it's 100% Calcium Chloride Compound). And started by adding roughly 1/5 of the 25lb bag, so 5lb or so. BTW, TFP recommends spreading the CH increaser pellets directly on the surface of the deep end of the pool, while the direction of this product says pellets should be desolved first in a 5 gallon bucket and then added to water. I followed the latter instruction, thinking the only difference would be temperature--but I didn't feel hot at all touching the bucket. Right after, I added liquid chlorine (48oz) as my daily routine to the pool. So, all seemed well, until I tested the water this morning.

A comparison of the parameters before and after

Parameter	Before	After
FC	6.5	2.5
pH	7.6	>8
TA	70	60
CYA	50	didn't test for the testing solution is used up
CH	240	275

The things that stands out is a sharp increase of pH, which is now off the chart--the test kit only shows up to 8, and it is much redder than 8. What has gone wrong? I was already being cautious by not pooring all 25lb of CH increaser to the pool.

I use Taylor K-2006 FAS-DPD test kit.

 

[Bperry]

Greetings!

I've been following the advice from TFP to maintain my pool for a few month now. It's been working great. The only parameter that's off is CH--it's been hovering around 240ppm or so.

In the attempt to raise CH, I purchased CH increaser here Amazon.com (it says it's 100% Calcium Chloride Compound). And started by adding roughly 1/5 of the 25lb bag, so 5lb or so. BTW, TFP recommends spreading the CH increaser pellets directly on the surface of the deep end of the pool, while the direction of this product says pellets should be desolved first in a 5 gallon bucket and then added to water. I followed the latter instruction, thinking the only difference would be temperature--but I didn't feel hot at all touching the bucket. Right after, I added liquid chlorine (48oz) as my daily routine to the pool. So, all seemed well, until I tested the water this morning.

A comparison of the parameters before and after

Parameter	Before	After
FC	6.5	2.5
pH	7.6	>8
TA	70	60
CYA	50	didn't test for the testing solution is used up
CH	240	275

The things that stands out is a sharp increase of pH, which is now off the chart--the test kit only shows up to 8, and it is much redder than 8. What has gone wrong? I was already being cautious by not pooring all 25lb of CH increaser to the pool.

I use Taylor K-2006 FAS-DPD test kit.

The FC reduction should stand out more than the pH. Get that up or you’ll be having an algae party.

Nothing is wrong, but the calcium addition maybe induces aeration or carbon dioxide dissipation which increases the pH.

Note though that you probably dont need to increase the calcium hardness anyway if your test results are already at 240ppm.

 

[vitruvian]

It's true, recently I lose on average 1.5~2ppm FC daily, a reduction of 4 does seem to be too much--I guess I was used to FC dissipation but not to the sudden increase of pH.

The TFP app shows the ideal target level range for CH is 350-550, with recommended safe range being 250-650. I was trying to raise is to 350. That reminds me of another related question--most other sources recommend 200-400, why does TFP's ideal target level so much higher?

Back to my current problem, should I balance the pH first, or add liquid chlorine first?

 

[Bperry]

It's true, recently I lose on average 1.5~2ppm FC daily, a reduction of 4 does seem to be too much--I guess I was used to FC dissipation but not to the sudden increase of pH.

The TFP app shows the ideal target level range for CH is 350-550, with recommended safe range being 250-650. I was trying to raise is to 350. That reminds me of another related question--most other sources recommend 200-400, why does TFP's ideal target level so much higher?

Back to my current problem, should I balance the pH first, or add liquid chlorine first?

Chlorine is always always always first order of business.

Note that the ranges TFP uses are really ranges. You get no extra points for being in the middle of the range vs either end. If you have hard water that you use to refill the pool from evaporation then we’d recommend trying to stay on the lower end of the range because CH naturally rises over time due to evaporation and refilling, unless you live in a really rainy area like me where i have to constantly drain the pool to prevent overflow of rain with no calcium in it.