Perhaps you are right then, and the only reason they are so white/clear is because you aren't running your lights. If so, lights on for a day or two would turn them brown, as anticipated.
The snot on the surface of the sump can be extracted a couple of ways:
Take a large soup ladel, and lower it into the water slightly so the slime pours into the spoon. Dump out in a bowl, repeat 50 times.

Take some white printer paper, and lay it on the surface one sheet at a time, peeling it off with the goo. Repeat until it is gone.
Siphon out what you can. The more proactive you are, the better. It almost looks like a chemical reaction, especially considering that you are dosing a two part. If you pour it in, it can crystallize in one area, and build on that with each subsequent dose. It should be added very slowly in an area of high flow, over 15 to 30 seconds per dose.
Just guesses since I don't really know what you are dealing with quite yet.