New Sundance 880 Marin Spa and need help

[dogman]

Hello all and thanks in advance. I have posted under the pool forum and follow the TFP method for our pool. I recently was the highest bidder for a charity auction and I now have a Sundance marin spa sitting on our porch. Was delivered early and i was not prepared. I apologize because i usually research this but i am somewhat in need of quick help and then i will research further. I was not home for the delivery and my wife does not recall what chemicals were added (other than chlorine and scale inhibitor. I have tested the water with my TFT100 and initial results are as follows:

PH 8.2 +
FC .5
CC 0
CH 100
TA 50

Forgot to run the CYA

what should be my first steps. They left a box of starter chemicals. seems like i need to get PH down (can i use muriatic acid under pool math); their starter chemicals have some product to use; then add chlorine - i have pool shock for the pool which i use daily vs store bleach; can i use that; then adjust TA and finally CH.



thanks

 

[chem geek]

If you want to use chlorine then see Using Chlorine in a Spa. Find out if the spa has an ozonator. If it does and you don't plan on using the spa every day, then you may find bromine easier to use. With an ozonator, the ozone reacts with chlorine and typically uses up half the FC even when no one is using the spa. So you'd have to add chlorine every day. You could get a saltwater chlorine generator for the spa such as the ControlOMatic TechniChlor as a way to automatically background dose. You would still dose manually after every soak to handle your bather waste.

Your TA is in a good place at 50 ppm since you want to minimize carbon dioxide outgassing that causes pH to rise. You need to add 50 ppm Borates you can get from boric acid from either Duda Diesel or from The Chemistry Store. You would then target 7.7 or 7.8 as your pH since aeration will tend to make it rise and it rises less with a lower TA and higher pH target.

You need to build up CYA initially which you can either do from pure CYA or you can start to use Dichlor as your chlorine source until you've cumulatively added 33-44 ppm FC since that will get you 30-40 ppm CYA. After that you switch to using bleach, but you use Dichlor once a month to make up for CYA loss. The rough rule-of-thumb for how much chlorine you need to use is that every person-hour of soaking in a hot (104ºF) spa with no ozonator takes 3-1/2 teaspoons of Dichlor or 3-1/2 fluid ounces of 8.25% bleach or 7 teaspoons of non-chlorine shock (43% MPS) where the latter is used with the Nature² system for those who don't want chlorine or bromine. However, the real rule is to add whatever is necessary so that you sill have a chlorine residual for the start of your next soak or next background dose. Usually people prefer to start with 1-2 ppm FC so that they don't notice the chlorine during their soak.

As for CH, you only need 120-150 ppm to control foaming.

 

[dogman]

thanks Chem Geek.

I stopped by the spa store to pick up an owners manual. They also provided some additional information. The spa also includes an Ozonator system and they inserted a SunPurity sanitizer cartridge. Couple of questions: Are those worth the money? I do not use such items in my pool and strictly follow TFP method with no problems. seems expensive to replace every 4 months.

With this and the ozonator he said i should keep FC around .5 - 1 which seems a little low to me. Does that sound right? Also i should add "shock" after each use about 1.5oz. won't this really depend on how much FC i have before hand and routine maintenance level?

thanks

 

[chem geek]

With an ozonator it's going to be difficult to maintain a chlorine spa unless you use the spa every day or two because ozone reacts with chlorine depleting both and more than doubling the 24-hour chlorine demand to 50% or more FC loss.

The issue is not about having the FC low for the start of your soak. The issue is that it will be virtually impossible for you to maintain a low FC level with the ozonator because the ozone depletes chlorine.

If you only use your spa on weekends, you might consider using bromine instead. Ozone can create more bromine from a bromide bank though eventually depletes it (by creating bromate), but that takes longer. Up to you.

The SunPurity sanitizer cartridge is minerals (sounds like silver) so may be similar to Nature². That's another approach you can take where you would use non-chlorine shock (MPS) as your primary oxidizer and the silver ions in conjunction with MPS would be a disinfectant, though technically only Nature² got approved with the EPA for this. Again, up to you. Even with silver+MPS you'll still likely need to shock with chlorine periodically to keep the water clear. MPS doesn't oxidize ammonia very much at all, for example.

 

[dogman]

thanks Chem Geek

the chlorine level has been a challenge. Latest tests after being gone for the weekend and i dosed the Chlorine on before we left:

PH 7.3
FC .5
cc 0
CH 100
TA 50
CYA 40

I am going to slightly raise the PH by adding soda to increase the TA. not sure what to on the Chlorine. we probably will use the tub every other night or so. I will need to read up on both methods to see which is easiest.