From https://www.swimmingpoolsteve.com/pages/spa-foam.html - Too many bubbles or too much foam is a very common complaint, especially from new hot tub owners. If foam develops when the jets are on and does not disappear within 60 seconds of the jets being turned off, this is the foam that needs to be addressed. What caused this foam in the first place? The dirt that builds up from oils like sweat, lotions, makeup; the residual soaps and shampoos left on your swim wear and on the hair and bodies of the hot tub users. There will be more foam if your filters are old or dirty, if the water is older, or if you run low levels of calcium as hard water does not promote bubbles. More often than not the culprit is a dirty cartridge filter that needs to be changed. A paper hot tub filter can be reused when cleaned with hot water and a degreasing agent (such as granular dish soap). Many hot tub owners simply rinse the filter with a garden hose to clean it which might remove some loose dirt like hair, but this is not enough to remove the oils that build up on the paper filter. The filters must be cleaned with a degreasing agent to remove the oils because that is what is causing the foam in the hot tub water. Another major cause of excessive hot tub foam is biofilm in the plumbing lines. Biofilm is organic matter and bacteria that has built up in the plumbing lines. This biofilm be cleaned by using a pipe flush product to flush out the lines during a drain and refill process and can rid the hot tub of that biofilm buildup. There are products like the Zorbie, which is a sponge that floats in the hot tub water to absorb oils, and antifoaming agents that can be added to the water. But these products only treat the symptoms, they do not solve the problem. By changing and cleaning the filters regularly, properly maintaining the hot tub chemical levels and using a pipe flush product during routine drain and refill you can decrease or even avoid unwanted foam in your hot tub. #SwimmingPoolSteve #hottubmaintenance #hottub ... https://www.youtube.com/watch?v=KIWy7POmb8U

From https://www.swimmingpoolsteve.com/pages/chlorine-vs-bromine.html - Most outdoor swimming pools use chlorine as opposed to bromine as the chemical sanitizer of choice simply because bromine is not able to be stabilized against UV damage. CYA (cyranuric acid) is used in chlorinated pools to prevent the sun from burning off the chlorine in the water. Bromine is not able to be stabilized which results in bromine levels reducing very quickly in direct sunlight. Additionally bromine is more expensive than chlorine which contributes to why chlorine is so much more popular than bromine in swimming pools. ... https://www.youtube.com/watch?v=mGg9g6qnHMg