Hotspring Vanguard Testing & Maintenance

[OregonRider]

Newbie here. I searched for answers to this question but wasn't successful in finding an answer.

I purchased a (new) HotSpring Vanguard spa 10 years ago. Until recently it never occurred to me that there might be a better way to maintain the water.

Here's our current routine: each time my wife and I use the spa we put in two scoops of MPS Chlorine-Free Oxidizer (http://tinyurl.com/lvunvbn).

Once a week we put in some unscientifically measured amount of HTH Spa Shock (http://tinyurl.com/k4ms4yr).

Once a week we use an HTH test kit (http://tinyurl.com/lsmsy8u) and adjust for pH by using HTH pH Decreaser (http://tinyurl.com/kclkgsl) and Increaser.

First question: Since I'm not a "chlorine" user, am I a Bromide user? The only other chemical I've heard of is Baqua Spa something-or-the-other.

Next question: What test kit should I be using and are there different chemicals that I should be using?

Thanks!

[chem geek]

You are a chlorine user because the HTH Spa Shock contains chlorine, though according to this MSDS it is calcium hypochlorite so you have to be careful not to use too much of this product because for every 10 ppm FC that is added it also increases CH by at least 7 ppm. A higher CH risks calcium carbonate scaling especially in the gas heater heat exchanger.

If you are using only MPS most of the time and you don't have Nature² or some other silver ion system, then the spa is not being properly disinfected. The only EPA-approved disinfectants for spas are chlorine, bromine, Baquacil/biguanide/PHMB, and Nature² with MPS.

How often are you using the spa? Does it have an ozonator?

[OregonRider]

I forgot to mention that. The spa has an oxonator and we use silver ion cartridges (which we change every 3 months).

We use the spa 2-3 times weekly for about 20 minutes per session.

[chem geek]

So you are primarily using the equivalent of the Nature² system with MPS -- silver ions with MPS -- with occasional shocking with chlorine "as needed" to keep the water clear. So when you say "we" I presume that is two people so soaking for 20 minutes is 40 person-minutes for each soak. With no ozonator that would require (40/60)*7 = 4.7 teaspoons of MPS but since you have an ozonator it might only need half that amount, so 2-1/3 teaspoons. I have no idea what the size of a "scoop" for your MPS chlorine-free oxidizer is, but basically you want to add enough so that you measure an MPS residual before your next soak. You don't want the MPS to get to zero ever.