base rock turning black?

[meadow]

i added reef rocks (caribsea) which is petrified coral to use as base rock in my new 55 gallon set up. its only been set up for 3 days.
90 lbs of aragamax bahama sand, 50 lbs reef rocks, specific gravity is 1.025 and temp is 80
ive been keeping the light on for about 6 hours per day so i have something pretty to look at, the light is a 4x65 pc light
this morning i noticed the reef rocks had this black powdery look to them, it almost looked like diatoms but it was black, i also noticed a bit on the sand.
is it normal for reef rocks to turn dark or blackish? they were white when i added them
i do have chemi pure in an aquamaster filter, could it be chemi pure charcoal dust?? i did rinse it before using
i ordered 45 lbs of fiji live rock that will be coming next week sometime, do i leave the lights off during the live rock phase? or can i keep the lights on for a few hours a day so i can look at the rock and see if i notice any life forms?
oh and i have good current, 2 maxijet 1200 plus the aquamaster 400 filter.
i ordered a prizm hob skimmer that will arrive next week also, i dont have a sump

 

[ChrisRD]

Hi Meadow and :welcome:

Any chance you can post a pic of the black stuff?

On the light thing - IMO having the lights on for a few hours a day during rock curing is fine provided it doesn't start causing a serious nuisance algae bloom. Some people cure them under full lighting periods.

 

[meadow]

heres 2 pics, they were bone white when i first placed them in, they actually look more natural now with that black shady stuff on it lol

 

[buleetu]

these rocks look cool,its a pity it could be something nasty,but then i think u should ask someone who might know a bit more about black stuff growing on ur rock

 

[meadow]

maybe its all the white powdery stuff washing off and this is the real color? lol i have no clue wha it is, weird since theres no life yet in the tank, so its basically a sterile environment
maybe the rock is coming back to life ...ok i know thats impossible hehe
the rock was cheap too, 50 lbs only cost 39.99

 

[bubblepuffer]

It's possible just charcoal dust.. even after you rinse the charcoal and most of the time after water go throught them, there will be some leach out. If you got a skimmer and water circulation, the skimmer should able to skim most of them out while they are floating on the water from the water movement. I usually got white powder in my tank when I install the Kent Phosphate Sponge, even after I rinse it couple of time ..and when I switch to Seachem Charcoal I do see some black powder leach out right after I rinse and sock the Charcoal many time..

 

[bubblepuffer]

It's possible just charcoal dust.. even after you rinse the charcoal and most of the time after water go throught them, there will be some leach out. If you got a skimmer and water circulation, the skimmer should able to skim most of them out while they are floating on the water from the water movement. I usually got white powder in my tank when I install the Kent Phosphate Sponge, even after I rinse it couple of time ..and when I switch to Seachem Charcoal I do see some black powder leach out right after I rinse and soak the Charcoal many time..

 

[meadow]

yeah it hasnt gotten any worse, so i think its the charcoal dust too
thank heavens lol :lol:
my skimmer should be arriving friday, i got the prizm :roll:
live rock is coming tomorrow oh joy