What problems come from high Total Alkalinity

[TreeFiter]

I'm wondering what kind of problems could be caused by high Total Alkalinity (240). In the situation I am thinking of, the pH was around 7.5, but the TA was up around 240. My boss decided we had to add ph- to the pool to lower the TA. When I asked him why, considering the pH was fine, the season is over and the pool would be closed in about a week, he said that high TA would stain the liner. I've heard that low pH would stain a liner, but never high TA.

If I understand correctly, high TA combined with elevated pH will result in scale. But since scale is more soluble in colder water, I don't see that being a real concern going into winter.

So I guess the question in all of this is, What problems can be caused by high TA?

 

[Christian]

High TA can cause a few different problems. 1) pH keeps going up. 2) Cloudy water. 3) Burning eyes and itchy skin. I have also heard it can cause reduced chlorine efficiency though not sure on that one.

 

[TreeFiter]

Is TA responsible for these problems, or is it really that high TA will often cause pH to rise, which in turn will cloud the water and cause burning eyes and itchy skin? High pH will also reduce chlorine efficiency.

 

[jblizzle]

I do not think the TA is a direct cause. The problems arise when the pH goes up due to the high TA.

There is a process described in Pool School about the correct way to lower the TA if so desired. Eventually, by correcting the pH, the TA will eventually come down as well.

Posted from my Droid with Tapatalk ... sorry if my response is short

 

[chem geek]

If the CH were quite high, then a high TA even with a normal pH could cause cloudiness and/or calcium carbonate scaling. Perhaps that is what he meant by staining (or he figured the pH would rise which can lead to metal staining).

 

[TreeFiter]

Well my argument against him was that we are getting a lot of rain which will lower the pH and ultimately the TA, the pool is filling up with leaves, which in turn will drag down the pH and TA. The pool is brand new and was filled from a water source that typically doesn't give us a lot of metal issues (tends to have higher CH, pH and TA, but not a lot of metals).

It also seems extremely irrational that we would want to lower the TA right before we close it, only to add the chemicals in a closing kit which includes a TA increaser.

This is a liner pool, so even scaling shouldn't be a big deal, unless the heater is running, but its so late in the season, I'm pretty sure they aren't going to waste a tank of propane to heat the pool just in time to close it.

As usual, I'm here to make sure I'm making good decisions about how to care for the customer's pools, and my boss seems to go against anything that makes sense. If you guys were in this situation, would you add 6lb of pH decreaser to this pool, or would you let it go until you open it in the spring?

 

[dmanb2b]

If it were me I would lower the TA. I'm not far from you (Dutchess County) and have fill water TA around 300+. Adding 6lbs of PH minus at once will likely dop PH too far. Lowering TA is a process and can be acomplished by lowering PH to 7.0 and then aerating the water to let PH rise back up and keep repeating, letting the acid additions drop TA and using areation to raise PH which does not impact TA. It took me 2 days to lower TA from 300 to 70 for a SWG pool, although in your case before closing, dropping to 100-120 area would also be fine. Dropping PH below 7 will risk damage to the liner.

PH minus also adds sulfur to your pool water, we prefer muratic acid be used.

 

[TreeFiter]

I guess I'm not seeing why it would be necessary to lower it. What bad would come of closing a pool with high TA?

 

[Stuamurr]

High TA usually results in the pH becoming hard to shift as it will for want of a better word "lock up", with your pH at 7.5 I don't see that being an issue for you and if the the pH is not drifting upwards, then I would in all likelihood not have any qualms about leaving it "as is" until your new season.

High TA will only be a problem if CH and pH are also high, I have never heard here or anywhere else that high TA will cause staining.

Regards
Stuart

 

[dmanb2b]

High TA will tend to make PH rise, not "lock" not sure what your are referring to Stuamurr? With also due respect to TreeFiter, he is a pool technician, not the owner, so knowing exact history of what PH tends to do may be an unknown here, but it TA is 200+ it will likely drift up.

High PH and high CH can promote scaling, even in a vinyl pool, but less likely