sand turning dark

[kevin254]

I started a refugium a month ago, it's a 30 gal with 200 - 250 gal flow, 4 - 5 inches of fine sand, cheato and live rock. 2 weeks ago I seen some of the lower levels of the sand turning dark (blue). A week ago I added 5 pounds of live sand and now I noticed a very small patch of almost black sand on top of the sand bed.

Is this bad or just part of the cycle process?

 

[Aquarist007]

It could be an algae or cyano. What macro algae are you running in the refugium
Until the algae really gets going you might want to run a power head in the refugium to get some of the organics moving out of there instead of them settling on the bottom. I had to do it for a couple of months but now it is fine because the macros are growing well now

 

[kevin254]

I just have a fist size of cheato and a little bit of red anger bush.

 

[Aquarist007]

<a href=showthread.php?s=&postid=12969580#post12969580 target=_blank>Originally posted</a> by kevin254
I just have a fist size of cheato and a little bit of red anger bush.

that's really not enough yet to be uptaking the phosphates and nitrates that can deposit there due to the reduced flow of the main tank.
I would add a power head for another month or so, remove manually what I could and not run the lights on the fuge for three days.