Let's see what @RDspaguy says.
He says "use chlorine". Dichlor/bleach is a good system.
if this is a chlorine based forum, why is there a bromine sticky at the top of it?
This is predominantly a pool forum, and bromine is not recommended for pools. So there's not alot of bromine experience here. Someone who knows bromine wrote those stickys, but most of the folks on here regularly know nothing about it. There is a plethora of information on it available online. Bromine has been used in spas for a LONG time.
If I thought chlorine would work for us, I would use it, but we travel so I can't rely on something that requires maintenance every single day.
Chlorine will work for you, and does not require daily maintenance unless the spa is used daily. There are ways even if you will be gone months at a time. Perhaps you are asking the wrong questions?
do have an ozonator which I believe lowers the recommendation to 2 ppm.
Bottom line, sanitizer (chlorine or bromine) reacts with organic contaminants and is depleted. The more contaminants, the more sanitizer is lost. 2ppm bromine is not enough to destroy what you bring in to the spa, so is not sufficient to keep it sanitized during use. Ozone does not help with this at all. However, if you shock after use (destroying contaminants) and close your cover, 2ppm is more than sufficient to maintain sanitized water with no (or nearly so) new contaminants entering the water due to the closed cover.
What about after I get out?
Shock after use. "Shock" means "oxidize", and both chlorine and mps are oxidizers. Oxidation also converts bromide into bromine, so you destroy contaminants and create sanitizer.
And then there is the party question... most of the time it is just going to me me and my husband in the tub, but I am sure we'll have friends over at some point who are gonna want to enjoy the hot tub too. What do I do then? Start with a higher level of bromine?
This is where a spa get tricky. You cannot safely raise your bromine high enough to not be totally depleted by multiple bathers. Ozone, being an oxidizer, may help with this, but it may not depending on the system. 24/7 ozone injection would be the only one that would, but some control systems turn off the ozone when the jets, or anything else, is on. Under these circumstances a feeder of some sort would be needed, but these have their own drawbacks and should not be used continually under normal circumstances unless sensor controlled.
For example, you could drop a bromine tab in your filter well. This will help maintain the bromine levels during use, but will draw high concentrations through the equipment which will cause damage over time. Floaters tend to end up in the skimmer anyway, with similar effect, and create pockets of high concentration in the spa that can bleach/stain the tub.
Apologies if these are stupid questions.
The only stupid questions are the ones you don't ask. Everyone tends to think water chemistry is simple, a+b=x, when in reality it's more like [(a+b)/(c(d^3))× cos(b+d)]/ 4.7=x.
and a heater of course.
