High TA

[theguok]

I just moved into a home and found that I had CYA levels of about 120. I decided to do a partial drain and just got done refilling. Apparently my home water has very high TA though, because despite the pool being at 100 before, now I'm up to about 180. So now I need to lower my TA. I just bought a couple of gallon bottles of muriatic acid to add, but am trying to develop a good plan on adding them. I've read to lower the pH to 7.2 then aerate to raise the pH back up. Well, according the Pool Calculator, that should only take 16oz of muriatic acid and according to my Taylor Chemistry Guide, I need to add a total of just about 2 gallons of acid to get the alkalinity down to where I want it.

Should I really be doing this little by little over the course of weeks to get the TA back down, aerating after each addition? I should add that I only have two returns on the pool, so getting a lot of aeration isn't going to be easy and I have no idea how long it will take to get the pH back up between each addition of acid. Could I also get the pH up by adding borax instead of aeration?

 

[linen]

What are you using for a test kit? Why do you want to lower TA? Is is because of CSI or fast ph rise?

Yes, you should lower TA little by little. I assume you have read: http://www.troublefreepool.com/pool-school/lowering total alkalinity Do not go much below 7.2 or you could damage pool/equipment. Then let it come back up using aeration. Using borax to go back up will just add to the TA (with a net small increase in TA...I think), that you just removed with the MA.

I am assuming that is plaster on concrete for your pool? Make sure you use poolcalculator to calculate your CSI level.

 

[theguok]

I have both a TF test kit as well as a Taylor one. (Had a Taylor one for a portable hot tub that I had before moving to the house that has a pool.) The reason for lowering the TA is because, well... it just seems too high! My pool is very cloudy and greenish after the water refill, and just trying to get everything in the right range.

 

[linen]

Sounds like you have more than a high TA problem.

Please post your test results for:

FC
CC
TA
CH
pH
CYA

 

[theguok]

I just added chlorine (bleach) an hour ago, so the FC and CC readings I can't say just now. The FC was low and I didn't measure CC at the time because I knew I needed to add chlorine upon addition of the new water. The other readings are CH = 350, pH = 7.5, and CYA = 50.

 

[linen]

I just added chlorine (bleach) an hour ago, so the FC and CC readings I can't say just now.

If you have qood circulation, you should be able to test about 30 minutes after adding the Chlorine. Post your results when you have them and how much bleach you added.

Most likely, from your description of the pool water, you are going to need to do the shocking process.

 

[aa62579]

When you need to lower your pH, make sure you are putting your current TA in the calculator. Your number from your first post doesn't seem correct. To go from 7.5 to 7.2, with a TA of 180, and 13,500 gallons, it would require 37 oz of MA. This will have to be repeated several times before the TA lowers back down. 2 gallons is probably close to what it will take for the entire process.

 

[theguok]

I agree that I need to add close to 2 gallons, but from my understanding it isn't a good idea to add it all at once. I added about a pint or so earlier (I just guessed at volume) and about 6 hours later, my pH is 7.3, TA is down to 140, FC is at 3.5 and CC is at 0.5. This morning when pool was full, I was at 0 FC. I added about 1 gallon of 10.5% stuff this morning when I took the hoses out of the pool, and added the rest of the 2.5 gallon jug (1.5 gallon) 5 hours ago. My CYA is still right around 40-50, and I assume that won't be changing and I'll probably stop measuring that.

So, should I aerate to get pH up before adding more acid? If so, how long will that take? Borax to raise pH, then acid?

 

[aa62579]

No borax. Just let the pH come back up naturally. Depending on how much aeration, that might be in the morning or it could be days. I don't know why you feel you need to lower your TA quickly, but if so, you can add acid each time it reaches 7.4 instead of waiting for it to get to 7.8.

 

[theguok]

The main reason from wanting to lower the TA is because the water is so cloudy. Do you think just keeping the FC levels up will clear that up despite the TA being so high?

 

[aa62579]

TA shouldn't have anything to do with the cloudiness. Possible small part with the csi, but you need to look more at chlorine and shocking for cloudiness.

 

[theguok]

OK. I had read in the Taylor manual that high TA can lead to cloudiness and scaling. I suppose I'll go ahead and shock the pool now and let the pump run all night and see how she looks in the morning. Then I can spend the rest of my night trying to figure out why my new home that supposedly has a built in whole house water filtration system is giving me water with so much calcium in it!

 

[Sportsman]

I started with a TA around 180 a year ago. I've been as low as 90 but I'm currently at 100. High TA in fill water is simply going to cause that. I just add acid when it hits 7.8 and let it naturally rise. If you are using liquid chlorine and not triclore, you will have no problem with it rising back. I only have one return and I have it pointing down as much as possible and I add acid every couple weeks. Now I don't always get it all the way to 7.2. I don't measure my acid. I know about how much to pour to bring it down and pouring straight from the jug minimizes handling the acid. I only overshot once and I simply adjusted the return to break the surface and turned the pump on high and I was above 7.2 in no time.

 

[linen]

I suppose I'll go ahead and shock the pool now and let the pump run all night and see how she looks in the morning.

It might be best if you do the OCLT next: http://www.troublefreepool.com/pool-school/overnight_fc_test. You can read up on the shock process here: http://www.troublefreepool.com/pool-school/shocking_your_pool. Please note the shocking is not a one time event, but a process. I would not worry about your TA until we figure out the rest.

 

[theguok]

I shocked twice yesterday and did the overnight OCLT last night. I lost about 2ppm, so I guess I'll continue with shocking until that is steady. Unfortunately, my pool gets the morning sun first thing in the morning, so I don't know how much I lost due to that, but I did check it not too long after sunrise.

 

[Bama Rambler]

You didn't shock twice. You may have added something they call shock but to actually shock your pool you have to raise the FC to shock level based on your CYA and hold it there until you pass the OCLT. That's shocking. If you just throw something in there and then let your FC fall below the recommended shock level about all you've done is thrown away the stuff you put in there because as soon as the FC went back down the algae started growing again.

 

[theguok]

Ahh... I got it. I added bleach to shock based on the Pool Calculator and my FC went up to about 18. That was mid-day. In the evening when I checked again, the FC was down to 12 and I added the bleach again to get it back up to 15. By morning it was down to 13.

So, I need to add bleach hourly or something keep the shock going?

 

[Bama Rambler]

Hourly is best as it makes the process go much faster. Think of it as two steps forward and one step back. The more often you can test and add the better off you will be.

 

[linen]

If you can not do it hourly, do it as often as you can and overshoot (calculate this) when you dose so that you remain above shock level for the period you can not check. However, I would not overdose any more than necessary, since this can effect pool surfaces and equipment.

 

[theguok]

An update...

Starting shocking the pool the right way on Tuesday. OCLT performed on Wednesday morning showed a loss of 2. Maintained levels at 15 throughout the day on Wednesday. On Thursday morning, OCLT showed a loss of 10!! I also noticed a lot more sediment at the bottom of the pool when I brushed it this morning. I've been keeping FC levels at or above 15. Is the fact I had a worse OCLT result last night a sign I should raise my FC shock amount?

Oh, and I'm not sure what I'm going to do, as I've unexpectedly had something come up where I need to be out of town this weekend, so not going to be able to keep shocking the pool beyond mid-day tomorrow. Is there anything I can do?