TA question

[Janade]

We purchased a home that has a 15,000 gallon, in ground, gunite pool. The pool was badly maintained before we bought the home, and we ended up having to drain it, acid wash, and then re-fill in May. However, since then the water has been sparkling and clear, and I've had no trouble maintaining the PH (around 7.4-7.6) and chlorine (around 2). However, my TA is always high (between 150-190). I have been attempting to lower the TA by adding muratic acid, then aerating (as I have read is the correct way to lower TA without also lowering PH). That does bring down my TA about 10ppm each time I do it, but then it creeps back up in a few days or so.

As I was reading, I noticed that many said that a higher TA reading is not really a concern, especially for vinyl, above ground pools. However, I wondered if the same went for an in-ground, gunite pool, such as mine. I have not noted any of the problems typically associated with higher TA, such as cloudy water or scaling (although, as I'm a new pool owner, I'm not sure I would know scaling if I saw it -- I'm assuming it is a build-up on the sides/bottom of the pool, which we don't have). If it is not a problem to have a constant TA of 150-190, then I really would prefer just to leave it.

The only mechanical parts I have to worry about are the sand filter and pump (no heater).

Any suggestions/comments are welcome! Thanks!

- Jana in New Mexico

 

[JasonLion]

Could you post a full set of numbers? In a plaster pool you need to keep an eye on your calcium saturation, which can errode the paster or cause sacling if it is out of balance. High TA can lead to scaling, and you wouldn't nessessarily notice it till it was already a serious problem. With a full set of numbers we can help you calculate your saturation index and see how much of a concern your current TA level is.

 

[Janade]

My pool store must be odd, because they try NOT to sell me things that I apparently need. For example, when I took a sample of my water to the store, they tested it and told me all readings were within normal levels. I explained that my TA was reading high (at the time, I had the test strips) and I asked if I should get a drop kit for more accurate readings. They assured me that the test strips were accurate and I did not need anything else. When I insisted that I wanted to get a drop kit, they sold me one. I had not read this forum yet, so I did not know what to look for in a kit. Mine only tests for TA, Chlorine, and PH, so the only readings I can give you are:

Chlorine: 1.5
PH: 7.5
TA: 170

The water in this area is extremely hard. We have a swamp cooler and after it had been running for a month, we had to spend a whole weekend scrubbing and scraping to get off all of the calcium deposits. I don't think I have to worry from a LACK of calcium in the water -- but I might have too much (if that can be a problem).

 

[JasonLion]

The other two important numbers are calcium hardness and CYA. If both your calcium and total alkalinity are high you are likely to be in the range for scaling problems. Without a calcium hardness or total hardness number it is impossible to be sure.

CYA, also called stabalizer, also factors into the saturation index, but it's main purpose is to protect your chlorine from sunlight. Because of the way CYA works you need to have different chlorine levels depending on your CYA level.

The best investment in your pool you can make is a good test kit. TF Test Kits has a very nice drop based kit that will test all of the major parameters.

 

[Rangeball]

Janade, one other issue with the drop test kit you likely have is it can only test for Total Chlorine, not Free and Combined chlorine.

The TF test kit Jason linked to is very complete will test for FC and CC, as well as the other tests you need.