Drop Equivalence for Borates?

matthewyounger

New member
Oct 8, 2019
2
USA
Hello, there!

I'm new to this forum, so bear with me here.
We've got a small hot tub, 500 gal. We've newly switched over to Bromine from baquacil (because baquacil sucks), but we plan to ultimately do Chlorine.
Regardless, I've gotten a Taylor K2006 kit. As most hot tubs go, the pH is usually too high. However, I had it this last week where it was too low. I used the base addition drop test included in the kit, then turned to the book for the amount of borax(20 mule team) to add. The problem: the booklet doesn't specify the drop-equivalent amount for borax. I tried using the same amount as what it recommended for (sodium carbonate, I think?), but it raised the pH way too high.

Pool Calculator tells you how much to add based on what the pH is, but my understanding is that using the drop test is more accurate than estimating with the colored windows, as it can be out of range, and you can under-estimate how much it really needed.

Does anyone know how much borax it takes to raise pH based on the K2006 drop test?

Thanks!!
 

JamesW

TFP Expert
Mar 2, 2011
16,598
The amount of Borax needed to raise the pH is about 1.9 times as much as the amount of soda ash.

However, you never need to raise the pH in a hot tub.

Between the heat and aeration, the pH will rise on its own as long as the TA is correct.
 

matthewyounger

New member
Oct 8, 2019
2
USA
That'd be great, once I figure out where the TA actually should be. I was following the recommendations by Taylor, which has the TA on the higher end, around 100-120. I believe that's what the book has said.
However, having it that high is actually causing the pH to tend higher than it did when I had it lower. I was reading around the forums here, and one of the guides says the TA should be around 50 in a hot tub. So, that's where I'm putting it. We'll see.

Thanks so much everyone!