My TA keeps creeping up

[avish222]

Hi,
My TA keeps creeping up.
I had it down to 125 and it is 175 again.
Initial TA was about 300 and it took me about a week and a lot of MA to get to 125.
Any thoughts?
Thanks,
Avi.

 

[linen]

Have you replaced much water lately? If you have, it could be your fill water has high TA. Have you used Baking soda, Washing soda/soda ash, Borax, or ph up lately? All of those also raise TA in addition to ph.

 

[avish222]

I didn't add any pH up agents.
I have the opposite problem, my PH also creeps up.
Just checked the tap water TA, it is 275.
Probably this is the reason.
Thanks.
Avi.

 

[avish222]

Can it be due to the bleach?
I have been shocking my pool and have used bleach since the SWG is not good for shocking.
Just noticed that the bleach I'm using has 3% chlorine and 1% caustic soda.
This is the only uncented bleach I could find (I'm not in the US).
Also, is this bleach ok to use or should I look for another one?

 

[anonapersona]

Every time you add water the TA will go up. Keep adjusting the pH and the TA will slowly decline. With high TA fill water it will be a constant issue. Rain water however will not increase your TA, hope for rain.

 

[257WbyMag]

You can lower your TA by following the directions in this sticky...pool-school/lowering%20total%20alkalinity.

Once you get your TA down to where you want it which would probably be around 80, you are just going to have to keep it at bay with regular acid additions since your fill water TA is already high.

 

[linen]

Can it be due to the bleach?
I have been shocking my pool and have used bleach since the SWG is not good for shocking.
Just noticed that the bleach I'm using has 3% chlorine and 1% caustic soda.
This is the only uncented bleach I could find (I'm not in the US).
Also, is this bleach ok to use or should I look for another one?

Caustic soda (lye) will raise ph and TA. You can see how much effect it has using the poolcalculator.com "effects of adding chemicals" section. It looks to me that is does move TA pretty fast...

 

[chem geek]

Can it be due to the bleach?
Just noticed that the bleach I'm using has 3% chlorine and 1% caustic soda.

Yes, that is a very high amount of lye in proportion to the amount of chlorine. Good chlorinating liquid that is 12.5% sodium hypochlorite has only 0.25% sodium hydroxide (aka caustic soda or lye) with a pH of 12.5 while 6% unscented Clorox Regular only has 0.063% with a pH of 11.9. Even cheap off-brand Ultra bleach is usually 6% chlorine with 0.25% lye with a pH of 12.5 so 1/8th the proportion of lye to chlorine compared to the bleach you are using.

For your chlorine, daily use of 2 ppm FC would raise the pH from 7.5 to 8.0 or 8.1 assuming your TA was around 80 ppm. You would be much better off finding a better source of chlorine, if possible. Either that or you are going to be needing to add acid regularly.

The acid you add to keep the pH down will counteract the lye from the bleach so the TA should not change in that situation. (it rises with the lye and gets lowered with the acid). Your rise in TA is most likely due to evaporation and refill with water high in TA (as you have noted). Use of a pool cover can help with that.

 

[HoleInOne]

What problems will high TA cause? I thought if everything else was ok high TA (300) was no big deal.

 

[linen]

What problems will high TA cause? I thought if everything else was ok high TA (300) was no big deal.

TA that high typically cause higher rates of ph rise, therefore frequent need for MA. High TA also can cause issues in plaster pools (see CSI in poolcalculator). My personal feeling is for vinyl pools as long as ph is realtively stable, then no need to change TA. However, a TA as high as 300 most likely will require lots of MA, but the use of that MA will also slowly drop TA.