Help identifying brown stuff

[paragrouper]

My tank is 7.5 months old. I noticed the brown stuff on the sand bed, primarily around the perimeter of the tank about a week ago. When I cleaned on Saturday, I noticed that it was slimy clumps when I went to remove it.

Below are two photos of patches on the sand bed and one of the stuff I remove. When I clean off the sand bed it reappears in 1-2 days.

my current tank parameters are:

Phosphate: 0.1
Nitrates: 9
specific gravity: 1025
Alkalinity: 7.8
Calcium: 420
Magnesium: 1340
PH: 8.1

these parameters are fairly stable, although I occasionally need to dose ALK and Calc.

any ideas on ID and remedy?

 

[Lavey29]

Probably diatoms from silicate in your salt mix

 

[paragrouper]

Probably diatoms from silicate in your salt mix

Perhaps, although my salt mix has not changed and my RODI TDS is 0.

 

[Lavey29]

Perhaps, although my salt mix has not changed and my RODI TDS is 0.

Have you done an ICP which shows silicate in your tank and RODI? I had high silicate levels in my RODI and same brown stuff on my sand. I changed to spectrapure silicate buster DI filter and now my RODI is 0 silicate.

 

[paragrouper]

Have you done an ICP which shows silicate in your tank and RODI? I had high silicate levels in my RODI and same brown stuff on my sand. I changed to spectrapure silicate buster DI filter and now my RODI is 0 silicate.

I have an ICP test on hand. I’ll send it in.

Thx