Borax Question

[FingersDLP]

New owner with salt water chlorine generator. I have read positive info on adding borax. I heard some expensive specialty pool salt may contain borax already but I am using pure solar salt.

If I want to add borax is it just a one time deal (or add when adding new water) or is this something that is supplemented more often?

Is there a good online pool calculator I can use to determine the amount to add? Do I need to get a test for it or can I just do the math, add it once and forget about it?

Thanks!

[chem geek]

The Pool Calculator here will calculate how much 20 Mule Team Borax you need to add to get to 30-50 ppm Borates which is the desired range to control pH and act as an algaecide. For every pound of Borax you add, you will need to add 7.6 fluid ounces of Muriatic Acid (31.45% Hydrochloric Acid) to keep the pH constant. One box of 20 Mule Team Borax is 76 ounces and will require 36.3 fluid ounces of Muriatic Acid to keep the pH constant. Borax is also used to raise the pH (it's an alternative to pH Up, which is the same as Arm & Hammer Washing Soda, requiring about twice as much by weight to have the same effect) which is why you need to add acid when you are adding a lot just to get the Borates level up.

You can read more about the use of Borates for pH control here where waterbear figured this all out and did experiments to validate its use. To get the main benefit of lower rise in pH, the borates should act as an algaecide lowering the chlorine demand and allowing you to turn down your SWG (power or run-time). This is because it is the hydrogen gas bubbles produced in the SWG that cause aeration which outgasses carbon dioxide into the air (pulling it from the pool) which causes the pH to rise.

Though you can just do a one-time add for this, the AquaChek Borate test strips are not that expensive given that you don't need to test the Borates level very often -- perhaps only 2-3 times in a season mostly to see if splash-out or backwashing dilution has lowered the level significantly. It would be good to have the test strips just to make sure you did the calculations correctly (including the estimate of your pool's water volume).

Richard

[FingersDLP]

Thanks! Very good read.

Brian

[Andy01]

That was a very helpful tip, quick maths!

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