New setup LR LS

[Osama]

I bought LR & LS from a hobbyist who had to take down his 6 year old system. the sand when stirred had a reddish muck, the sand itself wad black & white granular material.
Q1) Does this coloration mean anything
Q2. the rocks had good life on it, I noticed several worms orange color mostly. I assume that is good or such worms are pests?
Q3 The rocks had an orange detritus caked on their crevices.. Not everywhere but significant to be noticeable

I like the rock and I think the tank it came from was ignored for a while but 5 fish in there and few soft corals were Ok NOT great but alive..
Your opinion is greatly appreciated especially if any off you faced a similar orange coloration

 

[Anonymous]

I never worried about bristle worms - they didn't seem to harm much. I could have been lucky I guess.

I wash new rock or recycled rock in a bucket of tank water to rinse it off then let a power head circulate a lot of water through it for a day or so to blow the gunk out. Some sponges and other growth can look like detritus. I try to save something I think growing on the rock if it isn't harmful.