We have a 22foot round saltwater pool (roughly 10,500 gallons) that we lowered the pH to 7.5 and then put in 2 1lb bags of shock to get the light green cloudy water to clear up; unfortunately now we have black water… HELP???
The black water could be from metals present (especially if you have added a metal based algaecide at any point). This would require a metal removal agent to help control the metals. It could also be that this is a reaction between the algae and chlorine in which case, you should see a continual clearing and regular improvement. Filtration is an important part of the clean up. Make sure your filter is clean and running properly.