High CYA and TA

[sarahk]

Hello! I have the TF-100 kit and here is my reading (this is my second week using daily/weekly readings from the kit)
FC=8.5
CC=0
TA= 170
CYA=80
PH= my daily test shows it at 7.8 (I'm still sort of confused on this one - is the daily test how I read the PH, or am I missing something?)
My water is crystal clear

I know my CYA is high, and I've been told draining half the pool can help with that. If I don't drain half the pool, is the worst case scenario that I have to keep adding chlorine on an almost daily basis? If I do drain half the pool, will that help lower the TA a bit?

Also, the pool store owner I was working with (who I'm not seeing anymore) told me that I should have my TA above average, or else my pool heater will be ruined (copper coil heater). Is that true?

Thank you!

 

[Sandra B]

Hi Sarah. Your ph testing looks correct, if you're doing 5 drops of the red liquid then matching the color. Your CYA IS high, and if your pool is 7,000 gallons it might be worth it to go ahead and drain some out. While you can keep adding chlorine daily to keep your CL around 8 (and never below 5), it could pose a problem if you go away for the weekend, or vacation, etc. You won't be able to use pucks temporarily to keep your CL up, since most add more CYA, and it would probably take a lot if you could. So if you have plans for weekends away or vacations, a drain and refill would make it easier to maintain algae free.

To know if a drain will help your TA, go ahead and test the water you would refill the pool with and see what the TA of THAT water is. That's what you'd be putting back in. You can also lower the TA by taking your pH to about 7.2 with muriatic acid (which also lowers TA), then aerating the pool to bring the pH back up, then doing it again until the TA drops where you want it. Check out this poolschool article: Pool School - Lower Total Alkalinity

If your TA is too low, it can eventually eat into (not the technical term!) copper. If it's way high (and other chemical imbalances are present) it can cause calcium buildup in your equipment. It wouldn't hurt if you went ahead and brought it down closer to 100, but don't spend all day doing it. Do it over the next couple weeks by reading the link above.

 

[jblizzle]

Whether you drain or not, it is normal to have to add bleach daily to keep the FC above the minimum for your CYA level.

The TA might go down, depending on the TA of the fill water. Really the pH is MUCH more important for the longevity of the heater. The TA really does not affect anything other than letting the pH drop or rise more rapidly.

 

[sarahk]

Thank you both so much! I really appreciate you taking the time to help.