I've just finished decontaminating our spa after not being used for about 6 months. So much useful information here at TFP.
I'm looking to use the 3-step bromine system in the spa since it will only be used several times a week. I'm somewhat hopeful that the ozone generator will convert enough of the bromide to bromine to keep it at around 4-6ppm so I don't need to use bromine tablets in the skimmer door.
It's an old Sundance 850 Series Optima that has a 24x7 circulation pump. The ozone generator runs for pretty much all of that time that the circulation pump runs (as best I can remember). I've just ordered a new ozone generator after finding out that the existing ozone generator was no longer working (UV bulb was blown). I've ordered a Del Ozone Spa Eclipse that should generate between 50 and 70mg/h.
Anyway, onto the question... There are only a few places to buy sodium bromide here in Auckland, New Zealand, either in 250g or 500g containers. I've no idea how much I will need to create the necessary bromide bank in the 1800 liter spa (475 gallons). How do I find out - there was nothing that I could see in the Pool Math calculator to help. And I didn't find any numbers from any of the other similar threads regarding sodium bromide.