taylor test kit and borax

[BigDave]

The process for lowering TA involves raising pH by aeration. Chemically adjusting pH with borax will bring TA back to where it was.

[waterbear]

To substitute borax (decahydrate form) for the soda ash when using the Taylor base demand test use twice the amount of borax by weight then the amount of soda ash called for.
The decahydrate form of borax is commonly sold as 20 Mule Team Borax.

HOWEVER, this is only for raising pH when the TA is good and you don't want it to rise any higher and is not part of the TA lowering process, which involves dropping the pH to a safe level (7.0), aerating to bring the pH back up and repeating this process. When you add acid to lower TA you will also lower the pH by converting bicarbonate into carbonic acid (operative word here is acid). Carbonic acid, for our purposes is just carbon dioxide dissolved in the water (think club soda or seltzer). If we areate the water to drive out the CO2 (think shaking the bottle of club soda to make it go flat) we have lowered the amount of carbonic acid (operative word is acid) and the pH goes up. However, the carbonic acid is not converted back into bicarbonate but has been removed from the water so the TA does not climb. Once the pH has risen you can add more acid to lower the TA and pH again and repeat this process until the TA is where you want it.

[shawnw]

JimK, you are correct. BigDave, please enlighten me...I am obviously still learning! What exactly do I need to do to lower the TA if not muriatic acid? I definitely do not want to start a vicious cycle btw the TA and ph!

[PoolDoc]

My apologies, Shawn; you had 3 posts in moderation, and some how I lost 2 of them, trying to combine them.

[waterbear]

Lowering TA is a process and here it is in a nutshell:
1. Test TA and pH
2. Drop pH to 7.0 and not lower (lower can damage pools and equipment) It does not matter if you walk or slug the acid, it will have exactly the same effect. The act of adding the acid and dropping the pH is what lowers TA.
3. The trick now is to bring the pH back up without raiseing the TA. We do this by letting the CO2 created when we added the acid outgas. To speek this up we aerate the water any way we can.
4. When the pH is above 7.4 to 7.6 we test TA again and if it is still now low enough we repeat this process from step 2. When the TA is at target we stop and just aerate to bring the pH back up.
Here are full instructions:
http://www.poolforum.com/pf2/showthr...-HOWTO-amp-FAQ

If you are comfortable with handling Muriatic acid then the acid demand test will be helpful in getting the pH down to 7.0 quickly without overshooting.

The only time you get into a vicious cycle with TA and pH is when you try and follow a pool store's bad advice of putting a whole lot of acid in at once, usually by sligging it in the deep end with the pump off (which tends to drop the pH dangerously low and damage pool surfaces) and then trying to bring the pH back up with a chemical, which raises the TA back to where it was when you started or worse if you use pH up (sodium carbonate) which will actually cause the TA to go higher than when you started!

[shawnw]

My apologies, Shawn; you had 3 posts in moderation, and some how I lost 2 of them, trying to combine them.

No problem- Waterbear answered my questions - needed to know how to aerate pool for lowering TA. I have a pretty big waterfall at one end of the pool- will this serve as a good aerator?

[Watermom]

Anything that causes splashing will aerate the water. You can also turn your return jet upward so that it causes splashing at the surface of the water. That will also help.

[PoolDoc]

I have a pretty big waterfall at one end of the pool- will this serve as a good aerator?

That would be excellent -- water falls tend to make it very difficult to maintain either pH or alkalinity precisely because they are effective aeration systems.

[shawnw]

Thanks to all! And good to know about the waterfall! My spa spills over into the pool, also so that is something to take into consideration as well. Love this forum!

[shawnw]

oops-one more question- using my taylor test kit and testing TA, when color is supposed to change from green to red, is it true red? Or should I stop when it changes at all (pink)?