Can't see the photos, of course. If that's important, consider putting them on imgur or another photo site and give the link.

swimdaddy may be right if the make up water is coming from a well or if the pH has been much lower in the past and there is copper to be had (heater?)

But I would guess algae, species undetermined. If it's mustard algae, you'll be in a world of sorrow trying to contain it with CYA of 90 or more. That's nearly unmanageable-- you'll be carting in bleach by the truck load to fix it. Better to to get that CYA down by several controlled partial drains of the pool -- I have a gunite pool and do 20% drain and refill but you'll have to determine what is safe for your pool.

Yup, trichlor is convenient but that's what got you here! I'd recommend trying to reconfigure your schedule so you can start dosing with bleach and reserve the trichlor for very long trips. There's no calcium in the pool? I'd definitely get the alkalinity up to 70-80 ppm or so, you need some pH buffering.

The trichlor is likely contributing to pH decline. What are you using to get it back into range? Sodium carbonate? Borax?