Reduce Total Alkalinity Levels

Problems relating to pH and total alkalinity.
Increase ph, increase TA. Reduce pH, reduce TA.
pH chemistry advice and techniques for the pool.
hiperf2007

Reduce Total Alkalinity Levels

Postby hiperf2007 » Mon 15 Jun, 2009 19:24

hiperf2007 wrote:Where do you find this 20 Mule Team Borax? I have been on the phone about once a day with HTH on where to go with this pool. I walked out and dripped a stip again and it showed the following:

TH 1000
FC 1/2
PH 6.4
TA 240
CYA 0

The PH was up this morning too 6.8 but then it rained for about 45 minutes today. I don't know if that has anything to do with it but now it's back down to 6.4. I was thinking about just heading over to walmart for some PH Plus. HTH told me the most important things are the Chlorine and the PH. They said some people call in forever dealing with high hardness and high alkalinity and it seems some people just have a hard time bringing it into range and controlling it. I bought a $175 pool for a my daughter this summer and I have spend over $200 in chemicals and getting nothing. I told the guy on the phone I was about ready to pack the pool up and take it back and purchase a summer pool pass to our town indoor pool. :roll: Thats when he told me well the most important things are Chlorine and PH for water safety. I have though about getting some PH plus and getting it up to 7.2-7.5 and being done with it.


When I bought the pool, we also bought a HTH pool startup kit. It had the Shock, Clorine pellets, and the Stablaizer. Since then I have bought HTH metal stain control because we had brown water. Bad bad water. I built my own filtering system and within 24 hours it went from brown brown to perfect clear. Then the muriatic acid. That is all I have did so far. After 10 cups of acid in 4000 gallons, still no TA drop, just a serious drop in PH. I live in a small town where I don't have many options on some of the products you guys use. I do have a walmart, but all I see there is HTH products. Next pool store is over 2 hours away.


hiperf2008
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My Pool: Intex 16' x 42" 3700 gallon above ground pool.
Location: Dunnell

Reduce Total Alkalinity Levels

Postby hiperf2008 » Mon 15 Jun, 2009 21:41

OK, reading up a little on what you guys are talking about with aeration, I have hung my filters over the pool and turned on the pump. This is causing a 1 1/4" flow going back into the pool up on top now. This is causing bubbles going across the pool some. My PH is very low still. It was 6.8 but after the rain we had this afternoon it dropped to 6.4. From what I read now, my PH will rise. How long will this take? Then after it's up to around 7.2 I add more acid until it drops to around 7.0. Aerate more until it's back up over and over again. This will lower the TA and not touch the PH. I can see how this would work if Aeration does raise the PH if I'm doing a good enough job aerating as long as it doesn't take many moons and summer is over before it gets done.
Wingnut
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My Pool: 6500 gallon pool/spa combo
plaster surface
1.25 hp single speed pump
Location: Rancho Mirage, CA

Aeration & lowering Total Alkalinity

Postby Wingnut » Mon 22 Jun, 2009 12:17

I read chem geek's suggestion on lowering alkalinity and aeration.

My question is: how much acid is too much acid to add in order tolower the pH to 7.2? My current pH reading is 7.8 and my TA is about 200 (probably less is you account for the cyanauric acid in the pool (about 50 ppm).

I have had a constant battle with high TA, high pH, and low chlorine levels. We live in the southern california desert, so temperatures are warm and get hot in the summer. I am not so much concerned about the TA as I am the chlorine, which always seems low. I have been adding acid using the trickle method, but I can't seem to lower the pH. I have probably added 30 oz of dry acid over the course of 2 weeks, so I figure it is the TA that is preventing the pH from changing. I am up for trying the aeration method to reduce the TA, but am not sure how much acid I can add and in what period of time to lower the pH.

This is going to be a constant battle because I tested our fill water and it tested at 7.8 pH, 200 or so TA and about 1ppm of chlorine. The fill water has more chlorine than the pool water!

Thanks!
chem geek
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Reduce Total Alkalinity Levels

Postby chem geek » Mon 22 Jun, 2009 14:23

You can use The Pool Calculator to calculate an approximate dosage to get the pH down to around 7.0 (assuming 6.8 is the lowest reading on your pH test -- otherwise, use 7.2).

It sounds like the only way longer-term to keep the TA down is to use a pool cover to eliminate evaporation since refill will increase TA over time.
Wingnut
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Joined: Mon 22 Jun, 2009 12:03
My Pool: 6500 gallon pool/spa combo
plaster surface
1.25 hp single speed pump
Location: Rancho Mirage, CA

Reduce Total Alkalinity Levels

Postby Wingnut » Mon 22 Jun, 2009 15:02

I used the pool calculator and it suggested 41 oz of dry acid in order to reduce the pH, given the alkalinity levels. My question though, should I add it all at once? I have read that you shouldn't add more than a cup of acid to a pool a day. My fear is messing something else up with adding that much acid.
chem geek
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Reduce Total Alkalinity Levels

Postby chem geek » Mon 22 Jun, 2009 21:12

If you are using dry acid, I'd pre-mix it in a bucket of pool water and then slowly pour it over a return flow at the deep end. Then, brush the side and bottom of the pool to ensure thorough mixing. If you add it slowly, then you can add what it recommends. If you are unsure, just add half, wait an hour (assuming your pool has half-way decent circulation) then measure the pH again and add the second-half as needed.

If you can tolerate it, using Muriatic Acid will avoid the addition of sulfates to the water, but it is nasty stuff; the half-strength version fumes less.
charlie1966

Reduce Total Alkalinity Levels

Postby charlie1966 » Wed 24 Jun, 2009 16:42

what causes TA to rise?
chem geek
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Reduce Total Alkalinity Levels

Postby chem geek » Wed 24 Jun, 2009 20:51

Addition of pH Up (sodium carbonate), Alkalinity Up (sodium bicarbonate), evaporation and refill when the fill water has TA (which it usually does). Even addition of a non-carbonate base such as 20 Mule Team Borax or even lye will raise the pH and the TA. Aeration (carbon dioxide outgassing) will not raise the TA, but will raise the pH.
jackie

Reduce Total Alkalinity Levels

Postby jackie » Sat 04 Jul, 2009 09:38

right now I have a alkalinity of 190 and ph of 7.1, with 0 calcium hardness. I did have a the alkalinity of 280, and have removed some water and used muratic acid. I don't want my PH to keep going down, so how do I areate? I am not sure what is meant to do by that term.

Thanks for any help. It is the 4th of July here in Washington and a very hot day and I feel bad I cannot let anyone swim now.
chem geek
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Reduce Total Alkalinity Levels

Postby chem geek » Sat 04 Jul, 2009 12:20

Your TA of 190 is not horrible so you could use 20 Mule Team Borax (not pH Up products which will raise the TA more) to raise the pH some so that people can swim and then address the TA issue later (7.1 pH is not dangerous, but will tend to sting the eyes more than at 7.5). In fact, the high TA may not be a problem if you are finding that the pH gets low rather than tends to rise. This sounds like you are using an acidic source of chlorine such as Trichlor pucks/tabs. That will build up Cyanuric Acid (CYA) over time since for every 10 ppm Free Chlorine (FC) added by Trichlor, it also increases 6 ppm. So if you want to continue to use Trichor, you need to use a supplemental algaecide or phosphate remover. Your other option is to use chlorinating liquid or bleach instead, but need to add it every day or two unless you have a pool cover in which case you need to add it around twice a week.

Aeration is anything that mixes air and water so includes turning the returns to point upward with the pump on high to break the water surface, running waterfalls, fountains, spillovers, splashing the water (kids are useful for that) and of course keeping the pool uncovered exposed to the air.

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