At the start of the season I ran into an algae problem when my salt cell started to go. I got that cleared up but have ever since been fighting something accumulating on the bottom of my pool. At first I thought it was just green algae, it can't be picked up, and produces a brownish debris trail when brushed. So I started the slam again. I've been slamming for about 5 days now, keeping my FC at or above the target 20 for my CYA level (50), with no visible improvement. Water is crystal clear but I brush the stuff up, and it comes right back. Looking at it from the top of the pool it has a very light brown appearance. I guess my question is, how can I tell if this is mustard algae or not? I'll try to see if I can get some pictures when my wife finds our camera. I took some with my phone but you can't really see it very well. Thanks in advance for any help with this issue.