MPS is acidic so if the green, or at least some of it, is from metals then the green may have gone away when the pH dropped and then come back when the pH rose again.

If there is algae creating cloudiness, then just maintaining a normal FC/CYA level will not get rid of it because if the water is cloudy and if that is from algae then the algae is clumped enough that it can still grow inside the clumps faster than chlorine can kill it from the outside. That's why we shock the pool in this situation to raise and maintain a higher FC/CYA level to completely kill off the algae.

What I suggest you do is first lower the pH to at least 7.2 (but not below 7.0) and see if the green lightens at all. Then shock with chlorine to 20 ppm FC (assuming your CYA is really 50 ppm) and maintain that level which means adding chlorine multiple times during the day (or at least at morning and early evening if no one is around during the day). If it gets green again, that would be from the chlorine raising the pH. Don't worry about that. Just hold the high chlorine level and filter 24/7 (using both the skimmer and floor drain) to get rid of the cloudiness. Once you get to a clear green then you can deal with the metals.

Is your pool surface blue? If so, then you may have iron in the water (that's not uncommon in well water) since yellow+blue looks like green. Otherwise, green is usually from copper. That usually comes from use of a copper algaecide and is not usually in well water.