Does anybody know what this is?

[Shadows Reef]

i found allot of whatever this is in my overflow box and I have no idea what it is maybe heavy detritus build up but I’m not sure it all settled on the inside of my overflow box which is blacked out so I never even knew it was all in there.

I noticed on my apex that my max flow down the overflow was allot slower then it use to be on max. And my flow for my return pump on max is pretty much the same. Anyway So I cleaned it out just now and just a bunch of this stuff keeps coming out. I’m just cleaning it with water right now but I think I might do a 10/1 muratic acid soak for 5-10 minutes. But what is this?

 

[DSC reef]

Looks like spionid worms and detritus

 

[Shadows Reef]

I never knew detritus could build up like that in my overflow but it’s clean as a whistle now

 

[DSC reef]

Detritus um...finds a way