Hi all. Hope you experts can help me on a CSI question, I've read, and thought, and worried over this, then read some more, but I need some hand-holding.
My pool is now around 8 yrs old; I've had it for the last 4. Over the last year I have have a few strange things occur, which I am now attributing to early-stage plaster delamination: small "volcano" calcium deposits on the pool floor and steps; calcium drips on the walls; some "cracks" or crazing on the floor, and finally darkening areas, almost like color streaks, on some pool walls. This was accompanied by a meteoric rise in my CH. I keep a log on my pool testing (TFT-100) and the CH has gone like this:
7/23/11: 170 (first test with kit)
7/28/11: 290 (I raised it)
8/05/14: 460 (starting to panic and really read up here)
9/28/14: 760 (drained about 1 foot of water & replaced, maybe 10% replacement?)
10/6/14: 570 (result of water replacement)
1/17/15: 650 (may be result of 8 inches of rain in January)
My tap water CH is 30.
As of yesterday, stats are:
temp: 51 degrees
CYA: 45-50 (sock hanging to raise to 70)
I am trying to balance my CSI to help with the calcium problem, but I struggle with this. With the current readings, my CSI is -.65. From Pool Math, in order to keep CSI close to zero, I need to left my pH stay higher, around 7.8 or so (adds .3), and raise my TA to around 80 (adds .3). Adding the CYA has a small opposing effect (minus .1). This would get me close to zero. My TA generally drifts between 50 and 60 so I normally don't mess with it. My pH rises fairly regularly so I'm always pushing it down with MA. The high CSI confused me a bit, since I've been keeping an eye on it all summer and it was ok, but playing with pool math made me realize that lowering ONLY the water temp, from 90 (my summer water) to 50 (my winter water) has a huge impact.
I plan to add 128 oz of baking soda, which will have the effect of increasing the TA and slighting increasing the pH, so all is good with that. Before I go do that (half at a time), am I doing the right thing? Will the 80 TA pose any problems?
Do you believe that my out of control CH is due to delamination, given the other symptoms? I suppose the only cure is to some day replaster, but I'd like to try to manage it for a few more years if that seems possible. It seems too young to replaster! I've thought of calling the pool builders over to take a look (they're a big company in town and have done a couple equipment maintenance items for me over the last years) but don't know what that would help.
Photos can be added if they're helpful. The pool is sparkly and beautiful this sunny day . Just don't look too close...