When to Address Dropping TA Levels?

[JPhresh]

Following a water change-out in January to address a nasty CYA issue, I have had a nice chemistry balance that I've been able to maintain using only bleach, muriatic acid and a weekly scrub-down. However, on the most recent test I noticed my TA is now down to 70 ppm. (It's been drifting down from 100 since the change-out.) Is it time to act on that, or can I left it drift lower? If so, at what point do I need to act? Here's my latest data:

FC 3.8
CC 0
pH 7.4
TA 70
CH 225
CYA 45

Thanks in advance for the advice!

 

[jblizzle]

A TA of 70ppm is fine, it should not really go below 60ppm.
What are you adding to make the TA drop? This is usually only a problem if you are using an acidic chlorine source.

 

[Richard320]

I run my pool about 70 TA most of the time. Once you start losing a lot of water to evaporation and start refilling, your TA might actually start climbing again.

 

[JPhresh]

Thanks for the responses guys!

Richard -- I think you are right... My tap water TA is 90 and it's starting to warm up, so a rebound is highly likely.

Jason -- the only two products I have been adding to my pool since the January change-out are KEMTEK chlorinating liquid (10% sodium hypochlorite) and KEMTEK muriatic acid (14.5% hydrogen chloride). Is that an acidic chlorine source? Should I be switching to something else, or balancing it somehow?

 

[Richard320]

The Kemtek HCl is Muriatic Acid aka Hydrochloric acid. You're buying the half-strength stuff and paying for a lot of water. You ought to look around and see if you can't find some stronger stuff.

I buy 12.5% chlorine and 31.45% acid in refillable bottles. You have to buy the stuff in multiples of 4, but they'll usually mix-n-match, 3&1 or 2&2. Once you pay the deposit, it's quite reasonable. See if you have a dealer nearby. http://www.hasapool.com/dealer_locator_hasa.php If you've ever seen a pool service truck with orange or yellow milk crates in the back, that's the stuff.

 

[jcowart]

I would not really sweat the TA. Like what was noted I would not let it get below say 60. I don't see a SWG in your sig, are you fighting pH swings? Usually once the pH is lined out the TA will be at it's happy home. Every pool is a little different. Do you have a suction side leak. I have seen a leak not show up until the pump was running. It was enough to draw air in and keep driving the pH up and in turn drive the TA down because of the MA that was used to keep it in check.

 

[JPhresh]

Thanks for the tip Richard! I found a dealer not too far from my work... Been stopping at the local hardware store since its on the way home, but it looks like it'd be worth my while to start taking the occasional detour.

Jcowart -- I'm not sure if I'm 'fighting' pH swings (although I can tell you I'm not SWG)... My pH goes up a little less than 0.1 every day, so every two days I'm adding a bit of acid to keep things between 7.4 and 7.6. I previously posted an inquiry about this and most responses indicated that this is a normal state of affairs. That being said, I do have an issue with my pump which may be a suction side leak... I am very new to this and know little about pumps. However, I can tell you that after the pump shuts off, I can hear things gurgling -- it sounds like air getting into the system. Then when the pump goes on, it takes a couple of minutes to build up pressure and get a good flow going. (After that it runs just fine.) Is it possible that's part of what's driving up my pH? Should I be getting the pump serviced?

 

[jblizzle]

Hearing air gurgling when the pump is off could be a leak anywhere in the equipment. This should definitely not be happening and is the reason the pump must re-prime every time.

Do you see water leaking out anywhere when the pump is on?
Can you try to isolate where you are hearing the noise, or maybe be able to hear the air hissing as it is sucked in.