From what we can tell, there's nothing down there at the bottom of the pool. It's all just algae growth. We used a net, and brush, and came up with nothing. The pool was clear at the beginning of the summer towards the middle, and then they lost it. They don't want to close it like this, so we're fixing it now so we can close it in mid October once water temps drop to below 60, when algae has a harder time growing.
As of tonight, the spa was drained, scrubbed clean, the lines flushed with SLAM level chlorinated water, and refilled with clean water and chlorinated. We will now maintain the spa as clean. I added the stabilizer sock to the pool tonight, and will check again at 8am tomorrow. Hoping to see it lightening up. My buddy is swapping out the dirty cartridges every day, and it was VERY green today, so definitely getting it out...