Test results changing with the weather???

[larryca]

I have been testing every two weeks over the winter. I have been maintaining a CSI of -.6 to -.8 trying to burn off a white scale from my rocks and tile and black streaking marks on my plaster from two years of my pool guy keeping PH at 8.2+. There has been a slight improvement in the tile but not much on the rocks/streaks. The plaster looks better. You can see all the details of the pebble fina now. It looked chalky before. Anyway, I was plugging the numbers into the pool calculator and occasionally adding acid to lower TA and running the waterfall and a sprinkler nozzle to restore PH. Everything has been stable and predictable. I noticed, on the calculator, that if I kept everything the same and only raised the temperature to 78F, the CSI would be -.3. So I figured in the summer that is where I would be. So last week the weather finally hits the 70's and we got a tiny little rain (@ 1/4"). We haven't had rain since January. Today I tested the water and things have changed. below I listed the results I have had for two months with very little chemical addition and today's results. I have not turned on the SWG yet, solar is off, no swimmers, no rain drain or water added or lost. Just a lot more sun and longer days. I have read on TFP that temp shouldn't change results other than cya. What accounts for the changes?

Past results / Today
FC 3-5 / 0.5
CC 0 / 0
PH 7.5 / 8.0
TA 80 / 100
CH 280 / 330
CYA 60-70 / 50
SALT 3200 / 3200
W-TEMP 55F / 63F
CSI -.51 / +.18

 

[JasonLion]

You need to use more chlorine when the water is warmer. That is why FC is low.

The PH, TA, and CH levels have been going up because you have been dissolving plaster scaling off the walls.

The only number I can't explain is the CYA reading. I wouldn't expect that to change very much unless there has been some water replacement you haven't mentioned. The CYA test is a bit sensitive to proper lighting. If you didn't have bright sunlight the second time, that could account for it.

 

[larryca]

I have been adding bleach since water is too cold for SWG to work. I haven't added this week yet. So I expected it to be low. I am glad to know why the CH and TA have gone up. That was confusing since I haven't added or lost water. So if I continue to keep CSI low to clean up scale, will I end up having to do a partial drain to lower CH. I need to add salt and CYA but, I will wait if I have to drain anyway.

 

[ping]

Right now your numbers are fine and you do not need to drain any water. Right now I would get the chlorine and pH in line and the TA should start to lower when you start adjusting for the pH. When you get ready to turn the SWCG back on, bring the CYA up to 70 to start. Measure the CYA again before adding it.

The CH will go up some more with the low CSI, but you have a long ways to go before you need to replace some water due to high CH.