What does borax do to pool water?

[RobLane]

What does Borax do to pool water?
Is the tetra borate from Haviland better stuff?

[chem geek]

The borates in pool products are from sodium tetraborate pentahydrate while 20 Mule Team Borax is sodium tetraborate decahydrate. These are identical chemicals except for the water content. The tetraborate dissolves in water to form mostly boric acid and some borate ion.

This provides a pH buffer so lets one operate with a lower TA level that can help reduce the rate of pH rise from carbon dioxide outgassing. The borates are also a mild algaecide so can prevent some algae growth (mostly green algae, maybe black algae, probably not yellow/mustard algae).

[CarlD]

In other words, you can use either without concern, and raising your borate level to 50ppm should stabilize your pH, reduce your required TA level and make your water more inhospitable to algae.

Just remember that as you raise your borate level, you'll need to add muriatic acid to keep your pH in range, as Borax is our recommended pH-raising chemical.

[RobLane]

Will 20 Mule team replace Haviland's borate? It is rare to find anyone that has heard of borates. Thanks.

[CarlD]

20 Mule Team Borax is the first choice of most of our members.

[chem geek]

Just note that the required dosage is 31% more by weight (44% by volume) for 20 Mule Team Borax since it is sodium tetraborate decahydrate (10 water) so has more hydrated water content than the Haviland product which is sodium tetraborate pentahydrate (5 water).