After doing years of research, you should have concluded a couple things:
1. Add Live Rock before sand to maximize circulation under rocks and inside caves. You want to minimize the amount of rock that actually touches the floor of the tank. By digging the LR deep into the substrate, you are cutting off spaces for water to flow. In turn, you have created "dead spots" where detritus and uneaten food can sit and fester.
2. Tap Water has no place in this hobby, and adding LR to FW will kill everything living in the rock. You might as well stick the live rock out on your porch for a month. At least then everything will die
outside of the tank.
3. The "Water Purifier" is not an RODI unit - it's a purifier. Which means it probably runs through a single carbon membrane and then comes out of your faucet. That means Phosphates, and lots of algae. You should test for Phos immediately (you should be doing that anyway).
4. All of that rock is going to mean LOTS of hiding places - dont be suprised if you rarely see these tiny, expensive inverts.
5. Im on my 3rd salt tank, and when I first fill my display tank, that is when I see the most pods. I would not take your "pod siting" as evidence that your tank can someday sustain a mandarin.
My recommendation is to take the advice that you get here seriously. You are enthusiastic about your tank and that's great
, but you need to actually stop and listen. Whatever research you have done has resulted in some pretty big mistakes. There are some vets here that will walk you through this for the next couple months, but you need to be willing to take their advice.
I wish you the best of luck with your tank.