A little Spa experience here...
I've been in enough hot tubs, or spas as they are now called, to know that you can always lower the temperature.
You would be quite surprised by how much of a difference 4-6 degrees can make!
Most new spas top out at 104 degrees, while older models could reach 108 or even higher.
104 is indeed HOT enough, so hot it always grows uncomfortable within 20 minutes, maybe 30.
102 is my favorite temp for longer use - still nice and toasty, but I can normally make it for up to an hour...
For rolling, simply turn down the temp to 98, and you should be fine.
Even that is a little warm - shoot for the mid to low 90s and you can spend the entire roll in there.
The LAST thing you want to do is overheat while rolling, as this has been repeatedly shown to increase toxicity to the serotonin system.
Note - spas at resorts are more likely to use stronger chemicals, such as bromine or even chlorine (yikes).
So much bacteria makes it into the water that strong sanitizing and oxidizing chemicals are necessary.
You could request that the water be drained/refilled, but it takes many hours to reheat the water and it really only needs to be done every month or two.
Chlorine is WAY too active at higher temps, so it is normally only used if the water is nasty.
It evaporates rapidly, but can remain for several days if too much is used. Very unpleasant...
Bromine is much kinder at high temps, but should still be kept as low as possible - 1.0 ppm is preferred.
You should be able to smell it, but not strongly.
If you are getting into water that has NO sanitizer smell - it BETTER be fresh water, or you are dipping into a bacteria laden-soup!
PH needs to be between 7.2 and 7.6 - since bromine has a high PH and often local water does too, it must be continually reduced. Any PH over 8.0 is irritating to the skin and nose, and it reduces the effectiveness of the sanitizer (bromine). Any PH under 7.0 is acidic, and it is also irritating esp. to the nose/throat.
Adjusting PH can be touchy and in some cities it needs constant attention - just refilling the spa from evaporated water can throw it off. A slightly high PH is fairly normal, but a low one means that the chemical person needs more practice.
You can buy your own test strips, but they can be difficult to read unless you have experience with them.
If you don't want to bother maintenance just remember - you should smell a little bit of chlorine/bromine in the water but it should NOT be strong. If you have any irritation in the eyes or nose when the jets are running, the sanitizer is too high or the PH is off. You can leave the cover off and sanitizer will slowly evaporate over many hours - but draining a few inches of water and refilling with fresh is the only quick method.
The water should be crystal clear.
Cloudy water is an indication of bacteria or organic waste...think dead skin cells/body oils.
A slight green tint to the water is OK, because it is normally the alkalinity/PH balance causing it.
It should be crystal clear green, though! As long as the mist isn't irritating to breathe, the PH is ok.
Cloudy, smelly water is unacceptable.
Again, watch your temp setting - nothing above 98 degrees!
If you start to feel uncomfortable you need to get out right away.
And don't forget to sip some electrolytes, like gatorade.
It is better than drinking water because the salt content helps the kidneys remove the water buildup caused by anti-diuretic hormone from the MDMA.
Good luck.