Good morning everyone. I plugged my weekly test results into pool math and it is telling me to add baking soda, 423 oz.
CL 5-10
PH 7.2
FC 10 (Just added last night after heavy use over the weekend)
CC 0
TC 10
CH 1000 ( I need to drain when possible)
TA 60
CYA 60
I was told not to add the baking soda in another thread, but I am confused. If pool math is telling me to do it, why shouldn't I?
Poolmath will tell you to add based on what you input as your target. It just does the math -- YOU tell it where you want your levels to be. It only makes target suggestions. You have to decide whether or not they apply to you. Poolmath is likely also suggesting you to replace all your pool water. So why aren't you? Why take poolmath's advice on TA but not CH?
I've already made my argument why you should leave TA alone
here. I was trying to keep it simple. You want the long answer? You need to keep CSI down. That's the Calcium Saturation Index. A negative number indicates that it will start leaching Calcium right out of the plaster, weakening it. A positive number indicates it will start leaving Calcium scale on the walls. Scale is like grow-your-own 320 grit sandpaper right on the wall. People will scrape knees and elbows on the wall and get roadrash.
Go plug all your numbers into both sides of poolmath. Look at CSI.
Then go to the target column and change things. See what happens to CSI when the pH climbs to 7.8. It will climb over time. Guaranteed. Hover the pointer over the CSI row. "Potential to become scaling." Now leave pH at 7.8 and raise TA to 80. "Scaling likely." If you'd rather go from a risk to a sure thing, raise your TA. Leave pH at 7.8 and TA at 80 and see what happens if the CH rises to 1100, which it will eventually through evaporation and refilling with your 425 CH tap water. Now go back and reduce TA to 60. CSI went from a sure thing back to likely even at high pH and higher CH. What changed? TA went from 80 to 60, that's all. So why not just leave the TA at 60?
The higher the TA, the faster the pH will rise. The higher the TA and the higher the pH, the more likely you are to grow scale. So if you raise TA now, you'll be having to add acid again in a couple days to lower pH, which will also lower TA, so you get to buy and add both baking soda and acid and end up with a net gain of nothing....except possibly some scale on the walls, which doesn't dissolve anywhere near as fast as it can form.
As an aside, I'll bet the refill water has higher TA than the pool. So when you top off, you'll be raising TA anyway.
