TA/pH

Problems relating to pH and total alkalinity.
Increase ph, increase TA. Reduce pH, reduce TA.
pH chemistry advice and techniques for the pool.
Guest

TA/pH

Postby Guest » Fri 22 Jun, 2007 17:25

Hope someone can help...so confused! We have an metal frame pool, about 3800gal. Have had it up for about a week and have been trying to adjust TA and ph with ph Minus (TA is reading around 180-240 and ph 7.9 to 8.4 with hth strips). I have added almost a whole 7lb jar over the week of ph minus in attempt to get them down, but no luck. I called the number on the jar and they said I should add my dose in ONE spot, NOT predisolved, recheck in 12 hrs. I had been mixing and adding to entire pool...was this wrong? And I am not to disolve this stuff first?

Just out of interest, I am wonder what is the difference if I add it one way vs the other? Isn't it all just going to distribute evenly into the water anyway? And is it ok to add MORE of the ph minus...is that safe considering I have already added about 5lbs to this smallish pool?

Thanks in advance!


Guest

oops forgot to add

Postby Guest » Fri 22 Jun, 2007 17:30

Not sure if it makes a difference but we filled with well water...
Backglass
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Postby Backglass » Fri 22 Jun, 2007 20:05

Your TA is VERY high. If it were me, I would get a gallon of muriatic acid from the pool store. It's powerful stuff (be very careful), but loads cheaper than pounds of ph minus and it works fast.
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Postby chem geek » Fri 22 Jun, 2007 21:01

Yes, get Muriatic Acid, but also follow the procedure outlined in this post. You can only significantly lower your TA through a combination of aeration and acid addition at low pH. Just adding acid alone will take way too long. You will need a LOT of acid -- if you post your full set of numbers, especially your pH, TA (is the pH still 7.9 or 8.4 and the TA still 180-240), CYA, then I can tell you how much acid you will need (you already said your pool was 3800 gallons).

Also, please get yourself a good test kit -- the Taylor K-2006. It's far more accurate than test strips.

Richard
Guest

Postby Guest » Sat 23 Jun, 2007 12:45

Hi, thanks for the advice! My numbers this morning are

ph about 7.8
TA 180ish
CYA 30-50
hardness is 400
free chlorine about 4

(this is still using strips until I can get to the store for a better test and the muriatic acid if I still need it?)

Also, may be a dumb question, but the filter is considered aeration, right? I am running that over night and part of the day. We have a lot of little particles blowing in.

Thanks again!
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Postby chem geek » Sat 23 Jun, 2007 13:06

You water is way over-saturated with calcium carbonate so will likely be cloudy or will have signs of scaling. Maybe that's the particles you are referring to. I assume you do not have a saltwater chlorine generator and instead use a manually dosed source of chlorine. Anyway, lowering your TA will help with the over-saturation.

Your pool pump/filter is not aeration unless your water jets are pointed upwards and cause the water to ripple or break the surface (bubble). Aeration is splashing, waterfalls, fountains, spillovers, rain drops, or an air compressor or pump that blows air through a hose into a nozzle or pipe with small holes that you can put into the deep end of the pool.

It would take 2 cups of Muriatic Acid (31.45% Hydrochloric Acid) to lower the pH to 7.2 or 3.2 cups to lower it to 7.0 (I don't know what the lowest reading on your pH test is, but you want to lower the pH to one level ABOVE the lowest reading to ensure you don't go too low). It will then take an additional 9 cups of acid to get the TA down to 80, but not added all at once -- aerate to have the pH go up to 7.4 or 7.2, then add acid to bring it back down to 7.2 or 7.0 (probably around 2 cups of acid initially; less as your TA goes down) and repeat this until the TA gets to 80 and then stop adding acid and just aerate to have the pH go up to around 7.5.

Richard
Guest

Postby Guest » Sat 23 Jun, 2007 13:22

Thanks so much for that info...

The pool filter is pointing upward and does ripple somewhat but definitely no bubbles, so I can easily put the generator in to blow some bubbles in (how long/often will I need to do that to keep things level once we get there?)

I am not surprised we are overloaded with Ca. When we moved here they told us the well water was high in Ca, and we do get scaling on the sink fixtures etc. Haven't noticed any in the pool YET. The particles I am seeing are more from trees etc but the water is slightly more cloudy than when I originally filled.

Yes, I am manually adding chlorine so far.

After adding all that muriatic acid, is it safe to swim in (once everything is balanced) or do we need to wait a certain period of time? I am beginning to feel like we are taking a chemical bath with all the stuff I am adding! And now I know why people say pools are a lot of work ;)

Oh, also is muriatic something that I will be able to adjust in one day or so just by tinkering with it as you said, or will it take quite a while? It's going to be hot here in the next couple of days!! Thanks again, your advice is very appreciated!
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Postby Buggsw » Sat 23 Jun, 2007 18:55

I don't allow anyone in my pool until my water has turned over a good deal. At least 4 hours after adding a 2 or 3 cups of acid to about 10-15K gallons of water. I would not add more than that in a 24 hour period.
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Postby chem geek » Sun 24 Jun, 2007 00:00

You can wait on lowering your TA until after you're done swimming in the hot weather. If you splash around a lot, you'll raise the pH without changing the TA so that let's you later add acid to lower both pH and TA.

I've done circulation tests with GLB Party Blue dye that show that in a pool with both at least one floor drain and skimmer, all chemicals except PolyQuat mix very quickly and can be considered distributed in 30 minutes. But every pool's circulation is different and you can use Party Blue to see what's up with your pool (it dissipates in about 2-3 days). Or you can just add chlorine and measure it at the other end of the pool in 10-minute intervals. I add almost all chemicals very slowly over the return at the deep end.

Once your pool's TA is set, maintenance will be quite easy. As for how long it will take to get the TA lower, that depends on the amount of aeration but figure on a day or two. If you've got massive aeration, then it could be less than a day.

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