Ca and alk requirements for concrete pool

[TRHOD12]

I'm asking this for another person who has a concrete pool, and the pool stores have had her chasing her tail w/ chemistry. Sound familiar. LOL

What is a safe range for the levels of Ca for a concrete pool??? I know w/ the vinyl liner it is <500, but I couldn't find what it should be for a concrete pool. I tested this ladies water, and her Ca is 350.

What is the range for ALK for a concrete pool???? I know vinyl is 80-125, but what about a concrete pool??? This ladies ALK is 140.

Thanks for you help.

Blessings,

[aylad]

Hi Ted,

Calcium should be in the 200-400 range for a plaster/gunite pool. Her alk of 140 is fine for now, she can fine-tune it if she runs into cloudiness or scaling issues. I believe that 90-150 is a good target.

Janet

[TRHOD12]

Janet,

Thanks for the response. I didn't want to tell this lady something that was wrong. I know what the levels should be for my vinyl pool, but was unsure for a concrete pool.

This poor lady is about ready to commit harry-carry over the pool store BS that she is getting. I just didn't want to add to her confusion.

Again, Thanks,

Blessings,

[waterbear]

Actually, the TA depends on the form of chlorine used. Stabilized chlorines (trichlor and dichlor) and bromine tabs are acidic and require a higher TA of about 120 -150 to keep the pH from 'crashing'.
Unstabilized chlorines (cal hypo, lithium, sodium hypo and bleach, and chlorine produced by a SWG are more pH neutral and maintain a more stable pH when the TA is much lower (80-100 ppm). Many pools that use these sources of chlorine actually benefit by lowering the TA even more to about 60 ppm! (Less outgassing of CO2 so less tendency for pH rise!)

CH of 350 is fine.

If she is using trichlor tabs then her TA is fine (but I would keep close tabs on her CYA levels!)

[TRHOD12]

Evan,

I've just got her to the point where she has stopped listening to the Pool store.

I haven't got a CYA level yet, cuz I ran out of my test solution, but I plan on that.

Right now, I have here adding enough bleach to take her chlorine level to 12-15ppm based on the bleach calc for her pool size at night. I want her to get me a sample early in the am, to see if the pool is holding chlorine over night(check to see if she if fighting algae or not). I will go from there.

thanks all for your continued help. I remember joining on here a couple of years ago, w/o a clue about pools. I never dreamed that someday I'd be trying to help someone else out. I owe it to the forum and the great people who help out daily on here. A big thanks to all.

BLessings,