Is lowering high TA difficult when using a solar cover?

[mgarf33]

I am currently using an offline chlorinator with 3" tablets. I have 640# of salt and a Hayward AquaRite system with T-Cell 15 in the garage ready to go. Pool is in-ground ~25,000 gal.
The water is still fairly cool but swimmable at 72°F. So, I'm using a solar cover to bring up the temp until the Summer heat kicks in.
I'm finding the ph to remain fairly stable ~7.4. FC at 3.0.

What troubles me is it takes 4 drops to clear solution for the TA test.
Initially, my PB added a whole gallon jug of PH up, because the ph was low. FC was very low, so he added a jug of 12% chlorine.
A couple days later I tested again and the solution was bright red, and FC was also low again. So, I very conservatively added muratic acid in front of the return jets. It took a few days for my offline chlorinator to bring the FC back up 3.0

The ph is now good and hasn't moved much since, and FC is also stable, but TA is way high at 40ppm.
Solar cover is on most days and nights, weather has been rainy off and on.

Question is, does the solar cover make it difficult for TA to fall, and do I need to drop this TA before installing the SWCG? I don't want to scale this thing up.
Also, does this pool really need 16 - 40# bags of salt? The salt strip test shows little to no salt currently.

 

[chem geek]

The TA test doesn't go to "clear solution", but rather changes from green to red. Also, 4 drops meaning 40 ppm is not a high TA level. Why do you say the "TA is way high at 40 ppm"?

A gallon of pH Up adds somewhat over 40 ppm to TA along with raising the pH. Your pH might have been very low at 5.5 with low TA of 5 ppm or so. This may have occurred by using Trichlor tabs which are acidic so lower both pH and TA. I hope you didn't damage your equipment, such as your copper heat exchanger in a gas heater, in the process.

What test kit are you using? You should also be testing the CYA level since you have been using Trichlor.

 

[mgarf33]

I'm using a Pentair model 78 test kit. Just does the basics.
Ok I may be reading the chart wrong. Is shows to use drops of #3 solution until blue #5 solution turns clear or yellow.
So, 40ppm is good then?

 

[mgarf33]

The AquaRite SWCG instructions advise 80-120ppm for TA, so am I actually too low?

 

[Casey]

40ppm is on the low side. If you read Pool School you will find that we usually run TA anywhere from 70-90ppm with the very high end being around 120ppm.

My TA is sitting at 90 ppm and my pH is rock solid at 7.5.

 

[JasonLion]

When using trichlor tablets you want TA around 100 to 150. When using bleach for chlorine you want TA around 70-80. So either way your TA is at least a little low.

 

[mgarf33]

Yes, thanks for the replies. I did read the TA should be 80 to 120. However, being new to pool chemicals I was unwittingly adding a 0 to my results, thinking 400ppm instead of 40.

Ok, so I need to raise TA by ~ 2x to reduce pool chemical use and ph instability?

Does low TA matter if ph is balanced?
There seems to be conflicting answers on this question: http://www.troublefreepool.com/threads/73748-Worth-tweaking-TA-and-PH

Also, what should I expect when converting my pool to salt? Will the chemicals spike?

 

[JasonLion]

If the TA is too low (below about 60) any chemical addition will move the PH around a fair bit, and you run the risk of PH getting out of range. To lower the TA the more this happens. With TA at 20 this can be a major problem, while with TA at 40 the effect is present but only an issue for some chemical additions rather than all.

 

[mgarf33]

So, if I'm reading the Pool School correctly, I'm looking at adding baking soda?

I would like to add a little borax as well. I know I may have to follow that up with a little MA, correct?

 

[JasonLion]

Yes, baking soda will raise TA.

There are two reasons to use borax. One is to raise the PH, the other is to add borates to the water. If you are interested in adding borates, there is no point in adding "a little". Borate levels below 30 have have hardly any effect. If you want to use borates you should go straight to a borate level of 40 or 50.

 

[mgarf33]

Thanks, that answers my other question, is adding a small amount of borax useful?
I did read the whole borax treatment, but it seems a bit much at this time.
Does borax affect salt chlorinator cells?.
Never mind, your answer to the other thread salt system flaking answered that as well.