Our hot tub is on its last legs - the wood frame has deteriorated and it leaks some. Could be fixed I suppose - probably 10 years old. A BlueRidge spa model seats 4 or 6. I've replaced the impeller several times, maybe the pump and the new controls - we got taken there with a $1,000 module 'upgrade' and the guy didn't even leave an instruction sheet - it must have been a customer return that he was happy to unload.
Anyway - are there are hot tubs that utilize an ozonator to reduce chemicals? How about an ultraviolet light attachment like you see in ponds to kill algae. those 2 things would be an improvement i think. The heat would also help with the temparature.
Most of the time there we have only 2 people in the hot tub - so the extra jets for the other locations don't help anyone. Is there a tub that concentrates the jets to one or 2 places so the person gets a real blast?
we replaced the lid years ago and have them put a double layer of plastic around the styrofoam - that has worked well.