Some manufacturers recommend the cleaning of the tubes system with an anti-clog solution. That requires you to fill in a little bit the tub with clean new water, pour the solution and turn on the jet system to make the water circulate in the whole system and let it take action for the recommended amount of time. This anti-clog cleanig must be performed with the new cartridges already set. Dump the water after the anti-clog cleaning and fill in with another portion of clean water, turn on the jets again to wash any remains of the solution.
They don’t usually use real water jets, but instead use fans to “blow” the air around (also because of the 120 volt outlet), which causes them to cool down much faster than a regular hot tub. This cooling effect is only made worse by the fact that the materials they are made from lose heat much faster than the materials used on a regular hot tub. All in all, you aren’t likely to get more than 15 minutes to a half an hour of good heat out of an inflatable hot tub.