If its slimy, then its probably Cyanobacteria, often comes off in sheets.
Since you have already moved equipment, then the spores (?) have already been introduced, but sending some peroxide or bleach thru the tubes to waste (not into the tank) might help a little, because no one can tell thru a simple post if your new tank will have the same conditions, that allowed it to grow, as the old tank did.
I used Rid-X as a competitive bacterial medium to combat it in one of my tanks.
The Use of Probiotics in Aquaculture
Since you have already moved equipment, then the spores (?) have already been introduced, but sending some peroxide or bleach thru the tubes to waste (not into the tank) might help a little, because no one can tell thru a simple post if your new tank will have the same conditions, that allowed it to grow, as the old tank did.
I used Rid-X as a competitive bacterial medium to combat it in one of my tanks.
The Use of Probiotics in Aquaculture
