Black slime and substrate

[Mugster]

First of all I'd like to thank everyone for their great advice and tips. This forum has helped me to correct alot of the problems I've had in the past due to bad advice from my LFS.

I have two questions. First one. My tank is a 180 with approx. 150 lbs of LR and a 3"-4" deep substrate consisting of fine CC. Lighting is 2 Iwasaki 250W 6500k and 1 Iwasaki 400w 6500k and 2 160w VHO URI powered by an Icecap. I dose Strontium, Magnesium, and Iodine. A 55 gal sump (with a trickle filter which will be slowly removed over the next while), a DAS protien skimmer and the start of a refugium (some macro floating freely, no DSB) rounds out the setup.

I drip Kalk daily and all of my parameters are fine. I recently went through (still am for that matter) a bout with black slime. It used to envelop some of my rock and areas with low flow. I've since cleared most of it up but now I seem to get patches of it growing just under the substrate surface, binding the CC together in clumps. I've been siphoning the clumps out and rinsing and rerinsing it out before readding it back into the tank but it seems to reappear within a day or two. I'm also finding clusters of clear bubbles collecting on some of my turf algae.

I have a maintenance crew consisting of Turbo snails, blue leg hermits, scarlet hermits, and a couple of reef conchs(sp).

Second question. I've read quite a few articles about DSB which stated they can be achieved using fine CC, "sand", and a combination of both. Which is best?

Sorry for the length of this post but I am seriously frustrated at this point. :(