Got a stubborn TA in pool; some questions about spa water chem.

[bbrock]

Hi you all,
Here are the numbers for reference:
FC 7.5
CC 0
pH 7.0-7.7 (reducing to 7.0-7.2 when possible to lower TA)
TA 150 (high was 180)
CYA 50
water temp about 75

I am in the process of trying to bring my TA down from a high of 180. Yesterday it was 150, today it was 150. My TF-100 is about a couple of weeks old now, but yet I still continue to wipe the tip of the R-0009 (I think that it is the one) as per the instructions so that this does not affect the results. Yesterday, I added about 1 gal. of muriatic acid and today I added 138 oz.; fyi, I am only using the 14.5% strength as I am not comfortable with using the 31%. I thought I would really see a differnce in the TA today, but no. I even did the TA test a seond time, but used the 10 ml sample as per the extended test kit directions. My result this was 175. Also, I am running my pump/filter longer, about 7-8 hr for aeration; normally, I run it about 4-4.5 hr right now. Am I missing something? And, to bring down the TA, does the pump need to be run this long (> or = to 7.5 h)? It is the reduction in pH to 7.0-7.2 that is lowering the acid, right? If I am thinking about it correctly, it is only the aeration that is needed to bring the pH back up.

This brings me to my spa. If necessary, I can post the following in the spa section. The pH in my spa is probably between 7.2-7.5. I use bromine in my spa, per the OTO test today, it was probably 8-10. I have not tested my TA lately, so I will get around to that when I have a chance. Per Waterbear's instructions on using bromine in the spa, I learned the ideal bromine level is 4-6, and it is recommended to wait to use it until the level is <8. What is the recommended pH level in spas? Still the 7.2-7.8? How about TA? I think I read a post that stated it is lower than in pools, maybe 40-60 if I recall correctly. I will have to look for that thread.

Tx for the help. Hope all are having a great weekend.

 

[JasonLion]

Lowering TA is a slow process. Expect it to take a while. Aeration raises PH, leaving TA where it was. There are various ways to get aeration, some of them involve running the pump and some don't. If you are getting aeration from the pump, then running the pump longer will get you more aeration.

For a spa TA should be the highest it can be while still allowing the PH to be stable below 8. Often that is TA around 40. In a spa it is very easy to provide lots of aeration so lowering TA can go very quickly.

 

[Richard320]

The more you can aerate, the faster the pH will come back up and the sooner you can knock pH and TA back down with acid. Just rippling the water will take days, as you've noticed. Just by chance, did the builders install a hose bib anywhere on your return plumbing? You could attach a garden hose to that and connect a lawn sprinkler and have that spraying down onto the surface. Anything you can do to make it look like the carbonation in a coke will really drive the pH up fast.

My spa spills into the pool, and when I set that thing going full bore with full jet action and blower, things change in a hurry!

 

[bbrock]

Right on! Thx for the great info.

Got an idea for aeration. I saw those examples on aerators in pool school, so when I have a chance I could make one, but to answer your question Richard, no I don't believe there is a hose bib in the return. This idea just came to me though after reading ur post about having a sprinkler shoot back into pool. I could setup my 1/4 hp submersible pump, attach a hose, and at the end attach a sprinkler and aim that sucker back into the pool. This way my pump does not need to run and I save on some electricity since my pump is a 3/4 hp. If this works, then I'll skip making one of those aerators b/c those would need the pump to run. Perhaps this idea is good enough.

 

[bbrock]

Just threw in my submersible pump on my second step, plugged it in, and it works great as a fountain creating lots of bubbles/aeration. I'll try to post a pic.