Lime green coating base rock

[AquaDan]

Tank is 4 months old this weekend. I've been doing weekly 20 gallon water changes for the past 3 months. The glass and water column are filled with pods.

I'm starting to notice a bright lime green coating on my base rock. Does not appear to be on the few pieces of live rock that I have in the display. I've read that this could be the start of some coralline but I did make the mistake of rinsing the rocks and sand in tap water back when I first set up the tank so not sure if the rocks are leaching something.

Still no fish in the tank yet, just a CUC of Nerites, Ceriths, Emeralds, Hermits, Porcelain crabs.

I drop a small pinch of New Life Spectrum pellets in the tank about every other day or so.

Here are my current parameters:
Nitrate: 1-5ppm
Phosphate: 0.03ppm
Alk: 143.2ppm (DKH 8)
Cal: 460ppm
Mag: 1470-1500ppm (just started testing for this so not sure if I did it correctly)
PH: 8.0-8.5
RODI water
TDS: 0ppm


I'm also running carbon and GFO dual reactor
Instant Ocean Reef Crystals

All feedback is appreciated. Thanks!

 

[NYGiants84]

Same thing happened in my tank... the lime green coating will go away on its own.. heard a million different reasons as to why this occurs from phosphates leaching out of the base rock to who knows what..

Anyways, I didnt do a thing an after a couple weeks it was all gone..

 

[AquaDan]

Same thing happened in my tank... the lime green coating will go away on its own.. heard a million different reasons as to why this occurs from phosphates leaching out of the base rock to who knows what..

Anyways, I didnt do a thing an after a couple weeks it was all gone..

Thanks Giants!