scale free chem for closing

[james-m]

I had my pool replastered last year, and after opening this year it had scaling issues. I lower CH since then.

When closing this year I read different opinions on this forum on whether a scaling free solution is needed during winterizing. I understand that if there are no known scaling issues + CH level is good, scaling free chem is unnecessary, but I did have these issues just recently hence I have a couple of questions:

1. Would you recommend using scale free chem on closing?
2. If yes, what is good scale free chem to use?

Thank you.

 

[Texas Splash]

James, an overwhelming majority here will say there's no need to use a product like ScaleTec if your CSI level (CH, TA & pH) is monitored to keep the water CSI level in the slightly negative side (see PoolMath). If your CSI is between -0.3 to -0.6 at closing you should not have any issues. If you chose to add a scale inhibiting product, that's certainly your call. They range around $30-$40 a bottle, and their reviews are mixed. Also keep in mind many of those products consume free chlorine, so by adding those products you may find your chlorine consumption increasing which could lead to other issues.

 

[duraleigh]

What is your CH level?

What is your pH?

What is your TA

What is the pH level of your fill water.

Fairly unusual to have a scale problem in New York.........where did you keep your pH last year?

 

[james-m]

thank you @Texas Splash and @duraleigh.

my chems are:

FC	4 ppm
CC	0.5 ppm
CH	400 ppm
TA	80 ppm
CYA	35 ppm
pH	7.5 ppm

> where did you keep your pH last year

7.5 ppm as well

 

[Texas Splash]

So your test results show the water "balanced", but slightly above the CSI zero line at 0.14. But if the pH was to float-up to 7.7, you cross the threshold into a CSI that has the "Potential to Become Scaling" at just over 0.30. You can manage it easily though. Soon you'll probably begin preparations to close. As long as you aren't using any cal-hypo chlorine, the CH should not increase. IN fact, if you lower the water level for closing and receive any subsequent snow/rain, that CH level should drop a bit. More importantly, if you lower your pH to about 7.2 right now, your CSI drops to the slightly negative side at -0.15. Doing that might also lower your TA to 70 which would lower the CSI to -0.21. Both of those are perfect to help prevent scale. The key is to use the PoolMath and look at your CSI row after you enter your numbers. Keep the water around -0.1 to -0.3 and you should avoid future scale build-up. If you ensure the CSI is slightly negative at closing, the minor rising effect of pH from cold water should not impact the potential for scale.

 

[jmikeb]

great answer texas splash?