I use K3 because of the larger size. I don't want the stuff all through my sump or getting in a pump.
I use será siporax and biohome media. and for me is the best media in the marker.
Where can I buy some of these water t bed media?
http://www.w-m-t.com/Products/WaterTek_MB3_Moving_Bed_Media.php Great amazing stuff, as good or better than k1 with the larger size so easier to contain, Also very much CHEAPER than k1!!