Chlorine dosage for a Spa with Ozone and SWG

[Isaac-1]

As you may know I recently bought a hot tub, now I am trying to come up with a maintenance schedule for chlorination, etc. I know this will take some fine tuning, and there are a number of factors at play, but I hope to get things close to an equilibrium point so everything flows routinely.

The tub is a Hot Springs Jetsetter J 215 gallon capacity, it is equipped with an Ozonator (new Del APG-U), as well as a SWG (Saltron Mini), and has a place for Hot Springs Freshwater (rebranded Nature 2 AG ion) cartridge (currently has cartridge of unknown age installed). The Ozonator is set up to run 24/7 same as the circulation pump, and the Saltron Mini runs X hours per 24, so always runs at the same time of day. Expected usage is 1 person 3-4 times per week for 30-45 minutes mostly in the evenings (to help with back pain). I hope to set the run time on the SWG so it will run overnight and allow FC to drop back down some before the next day's use. CYA will be kept in the 30 ppm range (using pool water to fill the tub (it is nice to be able to refill the tub in about 3 minutes with a fire hose).

I am currently working with an FC goal of 3.0 ppm for the SWG to maintain, allowing a drop to 2.0ppm before evening use. Then boosting back to 3+ ppm after soaking using 8.25% bleach. Do these numbers sound sane to you, when using an SWG plus supplemental ozone, also should I worry about the nature 2 stick? The trouble I am having now is knowing how much I should boost FC after tub use to oxidize bather waste, there just seem to be too many variables and I don't want to stay out of the tub for a week just to balance the SWG operation. Any advice you can give on this subject is most welcome.

Ike

 

[chem geek]

Ozone reacts with chlorine so when you aren't using the spa for an extended period of time you might need to turn up your SWG on-time to maintain a sufficient chlorine level. Your approach of running the SWG overnight presumably after your soak is a good one as it should let you start your soak with a lower chlorine level. 1 person 30-45 minutes would normally require around 1.75 to 2.6 fluid ounces of 8.25% bleach to oxidize your bather waste, but with the ozonator you may only need half as much or even less. Just see how much you need to add to maintain a chlorine level until your SWG kicks in. The amount of chlorine you add after your soak isn't an amount to get to a certain FC level -- it's whatever amount that it takes to not have the chlorine get too low.

The Nature² stick is superfluous and not necessary.