Actually, the best solution I've been offered regarding the slime issue was given to me by Orlando at GLA. He says it's from organic matter breaking down in the water column, as I've also heard from several members here as well. You can get a small skimmer attachment which you can attach when needed and run for about 5 minutes on the intake of one of your filters, then swap back to your normal intake. Clears it right up. You can get them at Drs. Foster & Smith pretty cheaply he tells me. Oh, and yes, that definately look like a whiptail cat of some kind.
Thanks Mind - I'll check it out!