Gonna re-up this this thread with a few images of my own. 1st is dinos of some sort, 2 thru 4 are different focus images of a clump of sand, from the substrate that appears to have diatoms. Can anyone much smarter than me (most of you haha ) ID what I’m dealing with? Some appear to have antennae. Aquarium is nearly 2 years old and this long fight started about a year ago when I had phosphates drop to undetectable for a bit. Most recent trends of parameters are: NO3 between 5 and 10, PO4 .06 - .14, Ca 440, ALK 8.6, Mg 1354. I figure some are likely diatoms, as I’ve had sky high Si, based on recent ICP results. I use 7-stage RO/DI for water, none of which have color change in resins yet and Tropic Marin Pro-Reef salt. Trying to diagnose Si, and have a fresh water sample in the mail to Triton just to rule that out. Any ID help/mitigation strategy would be much appreciated! Thanks to all you guys for reading!