High CH

[az240z]

Did a test the pool this morning and have the following:

FC 6.5
PH 7.5 -7.8
CC 0
CH 350
TA 140
CYA 50
I did a check of the FC yesterday morning and the FC was at 2 and PH at 8.2+. Added chlorine and MA per the poolmath and the above are the results 24 hours later.

Last complete test was done approx 2 weeks ago

FC 12
CC .5
Ch 275
TA 150
CYA 47??
PH 8.2

Question is why is the CH rising and how do I counter it??


History is I drained the pool 3 weeks ago, Slammed it for approx 1 week and have been on maintenance since.

 

[duraleigh]

Climbing CH is a chronic issue. Did you use Cal-Hypo when you slammed? That's a good source for lot's of calcium. What about your fill water? Have you tested it.

 

[pooldv]

Rising CH is common in your climate. What is the CH of the fill water? There are really only two ways for CH to rise, high CH fill water and evaporation or using cal-hypo to chlorinate/shock the pool.

It is fairly easy to manage your water chemistry to avoid scale, even with CH above 1000 ppm. Enter all your test results in Poolmath and it will calculate the CSI of the water. Keeping the CSI slightly negative, 0 to -0.3, will prevent scaling and also help your plaster and SWG last longer.

More here, Pool School - Calcium Scaling
and here, Langelier and Calcite Saturation Indices (LSI and CSI)

Letting TA drop to 60 or 70 will help slow PH rise. Aeration from waterfalls, bubblers, etc also contribute to PH rise. Running them less will help.

 

[az240z]

Will test the fill water in the morning. Slammed with 12.5% HASA chlorine. Used stabilizer. to raise CYA.

 

[az240z]

I did the CH test on the tap water and the reading was 225. Ph was 7.5 and FC was 6

- - - Updated - - -

I did the CH test on the tap water and the reading was 225. Ph was 7.5 and FC was 6.

Poolmath says the CSI is -.05

 

[pooldv]

That is pretty high and will definitely contribute to rising CH in your pool. When water evaporates it leaves CH behind then you add more water and more CH and it just keeps climbing. CSI is good. Trying to capture rain water to fill will help also lowering the water level before a rain.