Yeah, that's nothing that you want in your pool.
I would do this:
- Lower pH (already done with MA addition - test after 30 minutes of mixing to see if it dropped as expected)
- Get some more CYA dissolving - it's easy to add more and you can't remove without exchanging water, so assume you have 10-20ppm already in the pool and add another 20ppm. This should bring you up to the 30-40ppm range. You can check it after 2-3 days (it can take that long to show on the test). Get the granulated stabilizer/conditioner/CYA and put it in an old sock, and suspend it away from the wall in front of your return jet. Squeeze every now and then to help it dissolve. It might take an hour to fully dissolve or a day or two.
- Get more chlorine in the pool - target 30ppm on the
FC/CYA Levels. You can do this while the CYA is dissolving and assume it's 30ppm to start (and you can adjust later if the test shows more).
Does the pool show any visible algae (dead or alive) or cloudiness? Or does it look nice and crystal clear?