How to manage CSI; and calcium hardness increasing

[Sandra B]

Hi all. I've been TFP for three years now so nothing goes in my pool except what I know. I have two questions:

1) When I first started testing my pool in summer 2011 my CH was 170 and I raised it to 300. It's stayed around 300 (plus or minus 30) these last 3 years. Last test was 6/25/14 at CH320. Today I tested 7/21/14 and it is 400! I did the test twice. I tested my tap water and it's less than 100. Since 6/25/14 I have added MA and CYA only. I have a new salt cell so have been running on the higher side of FC (around 9-10) as I adjust my salt cell run time and % to get to an ideal of around 8. So what is making my CH rise? I know what I need to do to lower it (25% drain), but what is causing the climb? Before I drain I'll wait a few days and test again.

2) I have calcium scale, identified by calcium deposits on the bottom and sides of the pool. I attribute this to me not paying attention to PH frequently enough during the winter . The sides I can readily clean with a stone thing (don't remember at the moment what it's called) but I can't hold my breath long enough to do the bottom. So I've been trying to manage CSI in an attempt to naturally reabsorb the calcium. BUT, I can't find any reasonable combination of chemical balance in PoolMath to get my CSI closer to zero. I usually run around -.4 to -.5. What do I need to balance to drive my CSI closer to neutral, and is this what I should be doing? The CSI for the SWG/plaster preset "goal" is -.56, so I'm not sure if that should be my goal rather than 0.

Today's readings:

Water temp: 83 (was in the 90's the last couple weeks)
Salinity: 3.1
FC: 10
CC: .5
TC: 10.5
PH: 7.4
TA: 60 (dropped from 70 after MA addition so I'm just letting it ride and watching)
CH: 400
CYA: 65
Borates: 60
CSI: -.5

Thanks for your help!

Sandra

 

[Sandra B]

Gratuitous pictures

Calcium spot:


& long shot of calcium spot showing water clarity and sparkliness where not in the shade. The vacuum is 6.5 feet down.


Thanks!

 

[JasonLion]

CSI in the -0.4 to -0.5 range is fine for day to day balancing. I would raise the PH a little from what you have for normal use, say to 7.7, but that isn't critical or anything.

If you want to remove calcium scale by lowering CSI, which I don't really recommend, you would need to get CSI down below -1, and keep it there for a while. Doing that is called a no drain acid wash, and removes plaster from the pool surface as well as removing the scale. It also often takes months.