What is Normal acid add frequency with a SWG

[donaldm823]

It looks like I am adding 32-38oz of muratic acid (31% strength) every 4 days while using my autopilot SWG. Is this add a normal frequency and a normal amount?

This is my first full year with the SWG since I installed it at the end of the last season. I am attempting to follow waterbear's sticky on SWG water balance, adding acid at a pH of 7.8 to lower it 7.5 to 7.6 and then allowing it to drift up, but it looks like it drifts up 1 pH pt per day. Here are my present chemistry values as of today (6/11/08). Note I last added acid on 6/7/08 (32 oz):

FC 2.9ppm
TC 3.0ppm
pH 7.7
TA 77ppm
CYA 65ppm
CH 310ppm
water temp 88F
salt at 3000ppm
pool gets full sun all day (no shade)
30,000 IG concrete pool
Autopilot set at 55%, power level 2, and FC has been steady for last 3 days.

 

[el_steak]

That seems about right. I had to add a cup of acid every 2 days (my pool is much smaller).

3 weeks ago I decided to add borates to my pool and since then I haven't had to add a single drop of acid. The PH is rock solid at 7.4. For around 35$, my pool is trouble free and maintenance free.

Have a look at this sticky:

http://www.troublefreepool.com/sticky.php?s=4921

 

[duraleigh]

If I remember correctly, chem geek posts that, while borates slow the rate, the overall need for acid will remain the same.

 

[chem geek]

That's only true if there is no nascent algae growth and you therefore do not turn down your SWG on-time. Borates by themselves are an additional pH buffer so will let you add acid less frequently, but the total amount (per extended time period) is still the same. HOWEVER, if the borates are preventing algae growth that used to consume chlorine, then you will be able to turn down your SWG and that reduces aeration and pH rise and therefore total acid quantity as well, not just frequency of acid addition.

 

[el_steak]

Agreed, when it gets time to lower my PH, I'll probably have to add a lot more acid to lower it.

That being said, I'd rather pour a gallon or 2 once every 6 weeks (just a guess) than a cup every 2 days.

As it's stands now, I haven't had to add anything to my pool in the last 3 weeks. The SWG is working at 9% and my FC remains between 2.5 - 4 and my P.H. hasn't moved from 7.4

 

[mikester]

I have to add about a pint a day to keep up, but I have new plaster this season, so hopefully that will slow down eventually.