We have opened our pool for the first time in 2 years. We have PVC plumbing and no heater. We added the recommended amount of soda for PH/Alkalinity, shock, algaecide after having the water tested. We also replaced the sand in the filter. Water was already clear but after adding soda water became cloudy. We proceeded with the other items and backwashed several hours later and lo and behold…..the backwash water is blue!!! What is going on???? Thank you!!!
Is it possible that there are metals in the water (copper in particular) as this can cause the blue coloration to the water. You may consider a metal remover to prevent any staining if you suspect metals may be present. Also, what type of pool do you have? If painted plaster, you may be seeing some of the chemical extracted from the surface, primarily cobalt.