Filtering out a little suspected oil residue and very fine particles
Just setting up this 125 and just now I have it filled with h2o and 3 in. of very thoroughly washed black diamond blasting sand which is actually broken up 'coal slag.' From what I"ve seen the tank appears to have two different contaminants in it that I'd like to try to filter out.
First is a film on top of the water that probably indicates some type of oil that could only have come from the blasting sand. No smell at all though so I'd say there's not much of it in there. This exact blasting sand has been ok'd by lots of people on the net for substrate so I'm almost sure it'll be ok, I'd just like to try to get whatever's causing that film out of there.
Second is that when adding more of this sand I wound up draining out some of the water. Now where the water was on the side of the tank there's a whitish looking residue that when wiped turns out to be very fine black powder.
To filter both of these little things out my plan is to install activated charcoal and lots of floss into my filters and just run until everything is taken care of. I have no real timeline to get this done so I can run filters as long as need be to get these two little issues taken care of.