Mixing Chemicals

[Dano]

Hello All

Was wondering if you can mix Ph decreasor and Refresh( non chlorine shock )when I get out of the tub,if the ph is a little high, and refresh to oxidize, then let the pumps run for 20 minutes,or should you not mix them. My ph likes to climb all the time because of the salt tub I guess, and it would save me some time doing it this way

Thanks

[gman]

Dano,

I do not combine chemicals in my spa to save time. I apply them one at a time. I don't know what product pH decreaser you are using and I'm not anywhere near my chemicals to check my own products, but if memory serves me correctly, I believe the manufacturer specifically warns against mixing the pH decreaser with other chemicals. I seem to recall seeing a "Do Not Mix With Other Chemicals" warning on most of the containers of spa chemicals. I'm not a chemist and see no logical benefit to using my hot tub as an experiment or lab test risking health and safety trying dangerous chemical combinations just to save 30 minutes time.

gman

[jeffr72]

Dano,

Shouldn't be an issue. When I change my water I have a small bucket that I add/mix my chemicals in while the tub is filling. It consists of 20 mule team borax, ph decreaser, baking soda, dichor, and calcium chloride. There is a bit of foaming when the baking soda and acid mix, but the testing is right on when the tub fill is complete.

I have not had any problems with this in 2 years.

jeff

[PaulR]

I'd expect baking soda + acid to foam; if your acid source was vinegar, that would be standard bottle-rocket fuel!

Really, baking soda + acid together makes no sense. The baking soda raises TA and the acid lowers TA; you're doing two opposite things at once.

--paulr

[david_bilton]

Hello All

Was wondering if you can mix Ph decreasor and Refresh( non chlorine shock )when I get out of the tub,if the ph is a little high, and refresh to oxidize, then let the pumps run for 20 minutes,or should you not mix them. My ph likes to climb all the time because of the salt tub I guess, and it would save me some time doing it this way

Thanks

just grabbed a bottle PH down and under precautions "do not mix with other chemicals"these warnings are here for your safty please read them

[jeffr72]

Really, baking soda + acid together makes no sense. The baking soda raises TA and the acid lowers TA; you're doing two opposite things at once.

--paulr

I understand your thought and at first, it was mine as well. In my mind the baking soda is to raise the TA and the acid is to reduce the pH (raised from the borax). When I follow this recipe the TA and pH come out fine. If I leave out the baking soda, the TA is lower than I want.

jeff

[chem geek]

Acid lowers both pH and TA. So if you wanted to lower the pH without changing the TA, then adding acid plus a small amount of baking soda would do that. The bigger problem is mixing the two in a bucket of water. The pH gets lowered by the acid a lot more in the small volume of water in the bucket compared to the pool so any baking soda that is added has a LOT more carbon dioxide outgassing which will raise the pH with no change in TA. Basically, you just waste a bunch of the baking soda this way, converting it to carbon dioxide that leaves the water. Instead, don't add the baking soda to the bucket. Add it to the pool separately.

It's also not a good idea to mix other chemicals together in a bucket since they are far more concentrated and some chemicals have negative interactions. For example, you wouldn't want to add acid and chlorine together as this can produce chlorine gas. If you added borax or pH Up, then the pH can get very high and depending on other water parameters or if you added calcium or baking soda, then calcium carbonate scale can form.

So the easiest thing to do is to NOT mix chemicals in a bucket. You can dilute them one at a time if you want to (adding each bucket separately to the main pool water), but really even that is not necessary except for things that don't dissolve well such as calcium hypochlorite. Instead, slowly pour/add any concentrated chemical over a return flow in the deep end with the pump running and then to ensure thorough mixing (especially in vinyl pools) lightly brush the side and bottom of the pool.