Total Alkalinity in Salt Water Pool

[matt.burba]

I'm trying to follow the principles of this site, starting with the article on Water Balance for SWG pools, and I have a question:

I started by getting my FC where it needs to be, then added a bunch of CYA to raise from 30 to hopefully 70+ (will take sample in five days). The next thing to tackle is my TA...

My TA is high according to the article above (130 vs 60-80) and the article says this range is "VERY IMPORTANT" , so I'm getting ready to try to lower TA by cycling MA & aeration. But as I'm reading up on TA, I find this article - Pool School - Lower Total Alkalinity - which says you shouldn't lower TA just to hit a target, only to slow the rate of pH rising or a high CSI index - neither of which apply to me, my pH is too low right now.

So my question is, should I lower my TA or not? Perhaps just aerate to raise pH and allow TA to lower on its own over time?

Current readings: FC 3.0 (headed to 4+), CC <0.5, pH 7.0, TA 110, CH 400, CYA 30 (headed to 70+)

 

[jv92red]

What is the TA on your fill water? My pH tends to drift up with my SWG and spill over so I try and keep my TA under 90 to mitigate the pH up drift. My TA also creeps up because of my fill water so I go through the lowering process as well once in a while but my pool has a big spill over so with increased aeration and the SWG going so I'm adding pH at least once a week down from ~7.8 to ~7.5 which won't really affect TA much. I'll need to do a few 7.2 pH MA applications to get the TA back down.

With a pH at 7.0 you'll definitely need to wait for your aeration till you can do another MA addition if you want to lower TA. Actually, make sure the setting on your Sense & Dispense is set correctly - 7.0 seems kinda of low for a maintenance level.

And of yeah, Welcome to TFP!!!

 

[ping]

Welcome to TFP!

There isn't any need to rush and adjust the TA to 60-80. The reason behind keeping the TA in that range is because the pH usually rises quickly when a SWG pool has high TA. Keeping the TA lower should reduce the amount of acid used to control the pH, but at this moment you need to get the pH a little higher and then see the trend of the pool with your new chemical balance. After the pool has settled in, then you can target the lower TA if you want to.

Since you are just bumping up the CYA you will need to dial in the ORP and acid additions to control the FC and pH levels. We have found that ORP and higher levels of CYA can be a problem itself.

 

[matt.burba]

Thanks guys. I'm not entirely sure that my Sense & Dispense probes are working correctly (my pool was closed last year by a company that I don't think had any clue on how to winterize the probes correctly, and I had NO IDEA), so I have turned off the automated sensing for now. I do believe that my pH sensor was reading higher than it should, and it was dispensing MA into my pool unnecessarily and that's my problem with low pH. I have a waterfall from my spa into my pool, and the spa has jets, so I expect I'll have plenty of aeration to test that hypothesis over the next day or so.

Based on your advice, I think I'll aerate to get the pH up and recheck TA after that.

Also, I've never checked my fill water chemistry. Seems like an obvious rookie mistake...I'll do it tonight for sure!!

 

[zamazing]

http://www.troublefreepool.com/threads/104077-First-TF-100-test-results!

My TA is high according to the article above (130 vs 60-80) and the article says this range is "VERY IMPORTANT" , so I'm getting ready to try to lower TA by cycling MA & aeration. But as I'm reading up on TA, I find this article - Pool School - Lower Total Alkalinity - which says you shouldn't lower TA just to hit a target, only to slow the rate of pH rising or a high CSI index - neither of which apply to me, my pH is too low right now.

So my question is, should I lower my TA or not? Perhaps just aerate to raise pH and allow TA to lower on its own over time?

Matt, I asked this exact same question and got some answers in the 4th post of this thread: http://www.troublefreepool.com/threads/104077-First-TF-100-test-results!

 

[matt.burba]

zamazing -- LOL, I guess I'm not the first person to get turned around in all this information. So it looks like you ended up lowering your TA with MA and aeration. Were you satisfied with the results eventually?

 

[zamazing]

Lowering the TA is not as quick as just adding some chemicals using pool math. It's been an iterative process of gradually lowering TA by 10 PPM, aerating for a couple of days to get the Ph back up to 7.8, and lowering TA and Ph again by adding muriatic acid. You can't drop your Ph and TA in one big increment because your CSI index is negatively impacted by Ph. Like you, I started at a TA of 110 and have gradually got it down to 80 just this weekend (10 away from the GOAL).

I'm finding that the most important thing to pay attention to is the CSI index. It gives you the flexibility to compensate for the individual character of your pool while deviating from the standard pool school recommendations - some pools naturally live at different CH, TA, and Ph levels.

 

[ping]

Matt.burba, your TA lowering process will go fairly quickly if you run the spa and let it overflow as that will be a lot of aeration. My TA creeps up over time due to the fill water and when it hits 100 I go through the TA lowering process until it hits 60 and I get some relief from adding acid so often.