chemical question

[abarts]

We have been in a friends hot tub three different times now, and every time when the jets come on it's like alka seltzer when you first put a tablet in a glass. You can see this affect and it seems to be fizz on the surface about two inches high. It goes in your nose , makes you cough, not pleasant at all. He is using a soft soak product and claims everything is in balance. I think something is wrong or is this normal for other than chlorine cleaners? We have been in other tubs,(chlorine) and have not experienced this. Thoughts?

[chem geek]

Soft Soak sanitizer is the same ingredient as in Baquacil, namely biguanide/PHMB.  It is a chlorine and bromine alternative that is EPA-approved as a disinfectant for pools and spas.  One uses hydrogen peroxide as the oxidizer in such a system.

Not sure what the fizz is.  Perhaps his Calcium Hardness (CH) is low and is therefore promoting foaming, especially if people aren't washing off soap from their swimsuits.  Or he might not be using sufficient sanitizer and/or oxidizer and there could be a buildup of who knows what that is causing the problem (that is, I don't really know).

[wmccall]

We have been in a friends hot tub three different times now, and every time when the jets come on it's like alka seltzer when you first put a tablet in a glass. You can see this affect and it seems to be fizz on the surface about two inches high. It goes in your nose , makes you cough, not pleasant at all. He is using a soft soak product and claims everything is in balance. I think something is wrong or is this normal for other than chlorine cleaners? We have been in other tubs,(chlorine) and have not experienced this. Thoughts?

I'm guessing the fizz is just dissolved solids and his water, while appearing balanced and clean is just old.  My tub does that after a couple of months. I've gone as long as 4 months with the water looking great while calm, but it gets that way toward the end. Have them invite you over the day after they change the water. I'll bet you don't see that.  I use the clarity after you turn the jets off as a test of how old the water is.  If it takes more than a minute to be totally clear after having run the jets for at least 10 minutes, its time to change the water. If you tried my tub now, its clear after about 10 seconds.

[abarts]

Thanks for the info.

[stuart]

The "Peptic" effect that you're describing is common and I have to agree with Chemgeek, it's usually a water balance issue.

The TDS that Bill is talking about would have less to do with it then stressed water that comes with TDS.

Biguanide systems can and will often do the same thing but again it relates to water balance with them also.

Bromine and Chlorine work like a bomb on bacteria, exploding them on contact while Biguanide has more of a "Strangling" effect and is much less volatile and, in my opinion, much less effective.

A couple of things that will help in addition to water balance are enzymes and letting the spa breathe when shocking.

A good Di-Chlor system with a good ozonator will give you crystal clear water with little to no actual chlorine residule to set in.

Also understand that Biguanide is much more temperamental then bromine or chlorine...