How important are CH and TA?

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C

Cody

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Bronze Supporter
Aug 17, 2014
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Prosper, TX
I've been following the program for 6 weeks or so. Pool is awesome, water looks outstanding, and no more trips to Leslies!!

I've concentrated most of my effort on maintaining proper TC. I just did a full test and here are my current results:

FC - 3.0
CC - 0
TC - 3.0
PH - 7.8
CYA - 30 (I guess....I hate this test...a couple of days ago I got 40)
TA - 80
CH - 550

When I was just getting started, it was recommended to me to not worry about the CH or TA yet and to concentrate on a SLAM and getting used to maintaining TC....which I've done.

But now, my TA is a little off from what the test kit says it should be (but Pool Math suggests it's okay), and my CH is really high. Should I now take steps, using Pool Math, to correct those? Do you guys worry about those numbers? I really don't want to drain and replace almost half of my water to lower the CH unless absolutely necessary (water is expensive here, plus that would be a hassle), but I'll do it if needed. Looking for some insight from the pros here...
 
It is possible to manage your water with some parameters outside of the recommended levels by managing your CSI instead. Dallas water has high potential to scale, you probably noticed in your coffee pot, shower, etc. Maintain your CSI between -0.3 and 0 to prevent scale and dramatically extend your plaster longevity. Properly managed CSI can add a decade or more to your Pebble finish. Not managing it has resulted in people having to replaster their pool in less than 5 years. NOT under warranty. Pebble Tec sent you documents for start up and water chemistry management and CSI/LSI is a specific part of the pool owner's responsibility to manage.

More here, Pool Care Instructions Pebble Tec
And here, Product Registration Pebble Tec

More here on managing CSI and scale, Pool School - Calcium Scaling
 
You have a plaster pool so TA, pH and CH are all very important to maintain and extend the plaster's lifespan as much as possible.
Too much CH will cause scale to develop on your pool surface though. Until you can change out some water (the only way to decrease CH and CYA) maintain your pH at the low end of normal to help avoid scale.

Don't bother with figuring out the "TC" (total chlorine) as we like to monitor the individual parameters that make up the TC. FC + CC = TC. Its more important to know that if you have 1ppm FC and 3ppm CC you have a huge problem, whereas 3.5ppm FC and 0.5ppm CC is cool beans!

Do you use PoolMath to help determine your C.S.I number? Look down at the bottom after you fill our all your tests and see if you're in range or not. That is important to plaster pools, but you can tweak the individual elements to see how to get the best number. Play with it :)
 
I've never considered CSI, so thank you! Question...above, pooldv says it should be between -.3 and zero....but on Pool Math it says "Less than -0.6 is suggestive of problems for plaster, tile, stone, and pebble pools. Greater than 0.6 is suggestive of problems for all pools." And on pool math, when I plug everything in, it shows .4 in the left column, and .15 in the right column....what does that mean? Sorry for all the questions, just trying to figure out where the CSI needs to be and I'm happy to shoot for it.
 
Between -0.6 and -0.3 the water can become a little aggressive and increase risk of etching so I prefer to keep it between -0.3 and 0. With Dallas water anything above 0 will tend to have PH rise and begin scaling. I would set your CSI at -0.3 and let it rise to 0 and then take it back to -0.3. If you see any signs of scaling then run it a little lower.
 
pooldv said:
Between -0.6 and -0.3 the water can become a little aggressive and increase risk of etching so I prefer to keep it between -0.3 and 0. With Dallas water anything above 0 will tend to have PH rise and begin scaling. I would set your CSI at -0.3 and let it rise to 0 and then take it back to -0.3. If you see any signs of scaling then run it a little lower.
Click to expand...

Okay...thank you. I see that the CSI number is derived from several variables. When you are lowering yours to -0.3, do you do so tackling a particular variable, or does it matter how you get there?
 
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