I poured epoxy over starboard and sprinkled on some sand. I used a pour-on-epoxy which is used to create a high gloss finish on wood furniture. One the epoxy dries it feels like sand paper.
Water parameters: calcium 440ppm, alk 10dkh, magnesium 1300ppm, PH 8.1-8.3, temp 79-80F, phosphate .02, nitrate undectable