Expected timing of TA drop

[shacke]

I am trying to stabilize my upward pH swings. I know the TA reduction process can take a while but assuming I can drop to 7.2 with MA and aerate up to 7.4 daily and repeat, what time frame am I looking at? Currently TA 130 and holding. Any educated guess?

This week I have added acid 3x but it has not been every day. The first addition was pretty big to get it from about 8.0 to 7.2 and the last two obviously smaller doses. Once I get a fountain in there (should be today) I hope to make it a daily event. Luckily, I tested my fill water and it is TA 60

Thanks - once I get this done I will be adding borate to help keep things in check but I don't want to have to battle that buffer effect while I am bringing down the TA.

Evan

 

[PaulR]

The Pool Calculator shows that at TA 130 and 19k gallons, it would take about 28 oz of 31% muriatic acid to lower pH from 7.4 to 7.2. The Effects of Adding Chemicals section shows that 28 oz acid will reduce TA by 5.8.

So, you'd expect to go through that cycle about 5 times to see a 30ppm drop in TA.
--paulr

 

[shacke]

Interesting and now I am more confused. I am definitely not seeing any drop after all 3 additions - particularly after the first heavy addition. (I am using the TF100 kit and wiping down the bottle after each drop, btw).

 

[Richard320]

Interesting and now I am more confused. I am definitely not seeing any drop after all 3 additions - particularly after the first heavy addition. (I am using the TF100 kit and wiping down the bottle after each drop, btw).

It can be a slow process. The more violent the aeration, the faster it goes. If I set my returns to 100% spa, the spa looks like it's boiling. I've lost 30 ppm TA in 5 hours before!

 

[PaulR]

The technique has worked for many people, so I wouldn't give up yet. You could try taking pH down to 7.0, the process reportedly works faster at lower pH.

I've also sometimes wondered if the Pool Calc is making some simplifying assumptions that don't apply in all cases. I find I need a little more acid than it says, typically.
--paulr

 

[shacke]

Thanks - If I recall, there is a concern with dropping pH too low with a heater so I don't want to tempt fate.

I am waiting for that little fountain attachment to be delivered today. With that, along with the SWG and full blast through upward facing returns rather than the floor turbo cleaners, I hope to get near Richard's results!

I will not give up!

Evan

 

[duraleigh]

Go ahead and lower your pH down to 7.0 or, because you are being pretty accurate with your dosing, go on down to 6.8 since you will be bringing it up immediately. The aeration becomes more effective at a lower pH and your results should be more dramatic.

EDIT:
Well, I started this way before the last three posts but I'll still post it. You seem to be able to control your pH very accurately. With that in mind, you are certainly okay @ 7.0 and I would go to 6.8.

Damage to the metal in the heater coil is typically VERY, VERY low pH say 6.0 or so for a PROLONGED period of time....like a few months. You will only have the low pH for a few hours and I can't see it doing any damage.

 

[shacke]

Thanks Dave. I will lower it further. A lower level will be more helpful since logistically I can only add more acid once daily during the week and that may give me more room to do that.

I will post back for certain.

Evan

 

[shacke]

Down to 100 this am - rain again in forecast, dumped some more MA in to drop back to 7.0 - Looking better already.