So I just got my Triton readings back, and I guess I know why my tank is covered in diatoms. The usual suspects are PO4 0.025, Ca 484, Mg 1455, Alk 9.2, but Si 605 ug/l. On 8/22/2016 Aqua Medic had also tested Si at 3.2 mg/l. In trying to combat this unsightly mess I have replaced all of the stages of my 5 stage BRS RODI even though I was getting 0 TDS. I have removed most of my already extremely shallow sand bed. I recently rebooted the tank about 4 months ago to install a starboard bottom, and I only added 40 lbs of Carib Sea Special Grade, and now I probably have 20 lbs left. Skimmer is an ATB 840 V2, and it is working very well, so I am at a loss. Does anyone think it could possibly be my sand, can liverock leach silicates? I do run GFO, and carbon dose with vinegar, but the GFO doesn't seem to be doing much for the silicates. Should I remove the rest of the sand? Thank for any assistance.