20 mule team Borax or Super Washing Soda?


Jun 30, 2010
In preparation to change to BBB, I went shopping for the green box of 20 mule team borax (used to raise ph, Right ???) Was thinking it should say Sodium Carbonate on it. I picked it up and looked at the box, it says sodium tetraborate decahydrate. Is that the same thing ?

Then down the shelf a bit sits a box of Super Washing Soda and the ingredient listed Is Sodium Carbonate. It's a yellow box made by Arm and Hammer.
(Not to be confused with Arm and Hammer BAKING Soda which is of course sodium BICarbonate)

So I'm not sure which to use--the box that says it's Sodium Carbonate or the Borax that I thought was and isn't really.

Sorry if this is a dumb question, I'm new and will undoubtedly have many more before I get it all figured out.


Aug 21, 2008
If you look at my post count, you'll see that I am hardly an expert. :mrgreen:

However, when I was tinkering with my "stuff" earlier, I noticed that the Pool Calculator says you can use either. But it takes more borax than washing soda to achieve the same results, so personally, I went with the washing soda.


Mod Squad
TFP Expert
Apr 4, 2007
SW Indiana
Pool Size
Liquid Chlorine
No, borax and washing soda are not the same.

Borax will raise your pH and pretty well leave the TA alone. Washing soda will raise alkalinity some while it raises pH. You can see how it works in the pool calculator. Borax also has some other benefits as described in This post

chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
San Rafael, CA USA
Also note that if you are going to be using chlorinating liquid or bleach as your primary source of chlorine, you probably won't be needing either Borax or washing soda since normally the pH tends to rise or is stable and isn't dropping. So if anything, you might need some Muriatic Acid. I can't remember the last time I've added either Borax or washing soda to raise the pH (oh wait...at the start of this season when I added boric acid to increase Borates and when I added cyanuric acid I used some Borax to raise the pH, but I don't use any the rest of the swim season).


TFP Expert
Platinum Supporter
LifeTime Supporter
Jul 15, 2007
Eastern Pennsylvania
I've chosen to go with washing soda for the very few times I ever have to raise the pH.

I have a vinyl pool and use ~10% chlorinating liquid in combination with trichlor pucks, the latter primarily early in the season to raise CYA. Extended use of trichlor does tend to lower pH and that's when I add the washing soda. By the time the CYA is where I like it and I stop using trichlor the pH is at 7.5 and will ride there for the remainder of the season. My TA likes to be at 70 and rarely tests higher than that.


Bronze Supporter
LifeTime Supporter
Oct 6, 2009
Nazareth, PA
chem geek - thanks for explaining how the use of liquid chlorine/bleach helps stabilize pH levels and therefore lessens the need to use borax. I was preparing to stock up with the 3 chemicals used in the BBB method and was literally in the store with the 20 Mule Team borax box in my hand and thought "why am I buying this box now if I have no need for it yet?". Obviously I've been buying lots of bleach, and have even had to add baking soda to raise the TA level, but I've yet to need any borax to raise pH.

In fact, I have also been surprised that even during the curing of my plaster (which I guess it's still doing to some degree since the pool is only about 2 months old), the pH barely "spiked" like the service company predicted it would and so I've still got 3 huge jugs of pH Down sitting on the shelf!!!
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