Hi! I have what i believe to be metal staining in a spa but there may be another problem and I am just looking for advice. Going to make this as brief and info rich as possible.
There is a pebble tech spa connected to two heaters and has a stand alone sand filter and pump. When I first visited the spa the pH was <7.0. I added soda ash to bring the pH up but all it did was turn the water blue and flaky and left a blue ring around the top of the spa. I drained the hot tub and filled it with perfectly balanced water from the pool, also pebble tech. pH dropped back under 7.0 within a week. I began slowly adding ash over a period of 2 weeks and the water has become tinted blue again but the water is clear. However now there is a purple ring around the rim of the spa. According to Jack's Magic Blue handbook this is caused by copper and is known as blue haze. There is copper in the heater and I assume this is the culprit so my question is: Is the low pH causing the copper to degrade or is copper degradation causing the pH to drop in turn degrading the copper even faster? Thats the basic problem please feel free to request any more info and thanks for all the help!!