Total Alkalinity / Borax

[jrudge]

I am in the UK and have a 60,000 litre indoor tiled pool.

Chlorine is via a feeder with UV , and it is kept at 28 degrees C.

The pool is a few months old. Filled with city water.

I have had pools before ( outdoor) and never really paid much attention to anything other than PH and Chlorine.

Given this is indoor and hence a stable environment I am seeking to nail the chemistry.

The main issue is total alkalinity which is currently 175.

There are some scale deposits on the tiles which I believe Is linked to this

So adding HCL will reduce the TA and the PH.

You cant then use PH increaser as that then increases the TA.

So I have been using Borax - about 8 kg of it so far.

The PH is currently sitting at 7 and stable. but the TA is not really moving.

The PH is also minority low.

Borax is for sale in the UK but not approved for pool use.

There is the option of gallons of HCL and 25 KG of Borax but to fill perfectly nice water with a vast amount of chemicals is counter intuitive.

The other way is the aerate the water - but this is an indoor pool so all that will do is put the humidity shy high and I have no particular way of aerating it anyway .

Or of course just get the PH right and ignore it.

I would appreciate any guidance - I can load the pool with chemicals but to me that just not seem the way to go.

Thx for your help

 

[PoolStored]

With a high TA, the only implication is that pH will rise faster. No other implication.

You have two options.
1) Manage pH to keep it in the 7s and ignore TA. pH will rise naturally, when it reaches 8, lower again to 7.2 with muriatic acid. Repeat this and over time, TA will come down. When TA reaches about 80, stop lowering pH to 7.2. With TA of 80, pH should be fairly stable around 7.8-8.0 which is perfectly fine.
2) Use aeration to raise pH, then use acid to lower pH and TA, rinse and repeat. (here is a thread for you...https://www.troublefreepool.com/threads/lowering-total-alkalinity-ta-quickly-with-the-acid-aeration-method.298101/)

 

[jrudge]

Thank you.

I have seen no evidence to date that the PH will rise - but time will tell.

I was using Borax as apposed to aeration due the hassle of doing it and given it is an indoor pool - but maybe I just have to make something up.

Thank you for your reply

 

[PoolStored]

Borax will raise pH and TA...so you are fighting with yourself.

 

[mknauss]

When you use borax to raise the pH, that adds some alkalinity. It also adds borates to your pool water. The more borates in your pool water, the more your pH change will slow.

Borates in pool - Further Reading

www.troublefreepool.com

 

[jrudge]

Borax will raise pH and TA...so you are fighting with yourself.

Thank you.

That is interesting as Borax is stated as recommend as it does not raise TA which I why I was using it !

 

[mknauss]

It raises the TA a little. Not as violently as soda ash, or baking soda. You lowered the TA a little with the acid, and raised it with the borax.

Baking Soda = big TA change, small pH change
Borax = Big pH change, small TA change
Washing Soda = big pH change, big TA change. Probably more TA change than you want.

 

[pjt]

How are you testing? With a TA that high, pH will rise by itself (no action required). Manage the pH with MA and over time the TA will fall. What's the TA and CH of your fill water?