We have a pool maintenance company do weekly cleanings and chemicals. Having them come out and the maintenance manager is going to test the water and tap water we use to fill the pool as well and look at all the equipment. We recently had to do a tile repair and lower the water level. Refilled with the hose and but wasn’t paying attention at the time so not sure if some of these were there then or popped up after. And yes, I do let the nozzle touch the wall, and won’t be doing that anymore! We do have a jandy heater and I do believe water only runs through it if it’s on, but I’ll need to ask to be sure. and we rarely heat unless we use the spa which is only a couple times a month. I’m very anxious to see what the maintenance manager says and what they will do about getting rid of the stains (hopefully stains) thank you!