below is a copy and paste from my build log
I also installed my reefmat and without even having a roll in this thing its a total PITA for S500 owners. the pre-terminated side that screws into the rollermat leaked like crazy. I took it apart and it had ZERO sealant, major QC over site. I ended up using the sealant that came with the mat and its really ugly and still drips a drop every 6 seconds or so. I'll be going to my LFS tomorrow to get red sea to send me a new one. Also when you cut the main overflow you have to go above the sump line, there is no room to put pvc cutters in the pipe below the glass line. I was not willing to completely detach the overflow and cut it. Even with cutting above the sump its nearly impossible to cut the pvc with a normal scissor style pvc cutter. I ended up using one of those cable saw things that put a bunch of plastic into my sump which wasnt too bad to get out. I wish i had cut the pipe even higher up because the union is putting pressure on the back glass of the sump. Below you will also see the part red sea sent me to make the included hardware work with the reefmat on my tank, without this piece the reefmat will not work with Red Sea Max S line tanks without additional hardware/modifications!
I'm also not thrilled with how close the reefmat motor is to my sump. if the sump overflows this thing will 100% get wet. there is not enough room to put the motor on the other side of the unit in the Max S 500 sump.