Everyone has different water standards in each city and some tap waters are just not suitable for every hot tub. Some cities have softer and others harder water. If you have tap water filled with heavy TDS minerals and microscopic contaminants that are not filtered in the tap, it can mean the filter that comes with your hot tub is not right for your water. Other people are using well water which is different than a filter that would be used for tap water.
Even if everyone is clean going in the tub and if the tap water is not suitable, then it doesn't matter how clean and showered people go in. Most people that get hot tubs don't even clean their tubs properly. If someone is careless with their own bathtub and there is mildew and mold then they probably are going to have the same problem in their hot tub.
If someone has soft water then minerals must be added and if the water is very hard, then putting soft water can balance it out. Some people also add water softeners. If the water is not just right, it can breed fungi and bacteria and spread those diseases to whoever is bathing in the tub. Also, some of this bacteria and fungi (slime built up in the hose or piping) can harbor this bacteria and people are just filling their tub up with microscopic bacteria and they don't even know it.
By knowing the water supply, it can mean using a copper ionizer or a ozone system or maybe zinc ionization to purify the water. If you don't know your the type of water that is used in your city please look it up or email us your city and zip code and we will try to find the right purification for your type of water.
If the water is too hard, this can cause calcium deposits and the tub will not stay smooth. It can soon feel like sandpaper.
Note: Hotter hot tub water mean quicker bacteria reproduction. If you are the type to keep your tub very hot, a whole new level of sanitation is required. If the water is not balanced it can cause leaching of the hot tub acrylic shell. This can cause cracking and also blistering. This is rarely a problem with well water.
The best thing I have used for hot tub is an infused laser to raise the voltage and lower the cluster size of the water. A hydrophilic hot tub feels much better than a hot tub that makes my skin feel like a prune when I get out. This is one of the things many people don't like about getting out of the hot tub. If you want to send us a sample of your water in a bottle, I can test it.
I can also send you a some infused pennies to put under your cup or water bottle. You don't even have to put the pennies in the water, just under your cup or under the water bottle. Just one penny is enough. I can send a sample penny to anyone that is interested. I put about 75 cents worth of these pennies in my tub and it makes a world of a difference. See my video below. Or actually, see over 100 videos on my Youtube channel.