There's enough "wiggle" room to fit a 7" roll - just barely. It may get a little "scrunched" right on the spool itself (which is about 0.25" narrower than the width of the outer red roll holders). The only thing that I can see being an issue is that the diameter of the fleece roll seems much larger than the ReefMat fleece rolls (and the roll itself may end up being too wide to fit the ReefMat spools).
One of my suppliers carries these so I think I'll have to try it out.
I ended up going the "recycle" route as a slight deviation instead. So far I'm up to two recycles with no hits to nutrient levels.
@blaxsun … if you don’t mind sir you are needed I'd like to know alsoWondering if you ever tried the 7" roll out?
Also how did you recycle your old roll? bleach?