Best Way to Confirm Dinos?

[ecas12]

I have been going through the ugly cycle in my tank for around a month and a half or so by now (tank has been up and running for about 4 months now). When it originally started to develop I got brown spots over my sand and what looked like algae eventually started to grow on my rock, and I just assumed it was diatoms + algae because my nitrates hovered between 13-16 ppm and my phosphate between 0.01 and 0.03 (both using Hanna checker). I have two prickly ceriths and a few nassarius that turn over the sand really well, and when they do the brown spots just return. I went on vacation last week and when I came back, a lot of the brown on my rocks had completely disappeared but the brown on my sand has stayed. What I had assumed happened is the person feeding my fish underfed relative to what I normally feed, but my nitrates are currently at 17.4 ppm and I was only gone for three days. I have attached a picture of a large patch on my sand, as I am worried that I am now dealing with dinos instead of just diatoms. The brown spots disappear at night on my sand and slowly start to creep back up during the day. Is the only way to guarantee dinos by using a microscope?

 

[blaxsun]

It looks to be a bit more than diatoms but not necessarily dinos. You need a few conches to really scour your sand bed.