Why my live rocks turn black/deep brown?

[jiangmi]

I have a 90 gallon saltwater tank, only one fish (damsel) and several hermit crabs in it.
No protein skimmer, no filtration system.
Regular fluorescence light 4 hrs everyday.
Why are the live rock turning dark, especially the side facing up? Are they still live?
Thanks.

Joe

 

[tyler1503]

How old is the tank? Tanks can go through several stages before the rock "matures" and looks real nice. Most of these stages produce different types of algaes.

 

[jiangmi]

My friend gave me the whole tank a couple months ago. I moved everything here including the water.
I don't have a lot of time to take care of it, so basically just have a pump to keep the flow inside and lighting 4 hr every day.
I recently put one damsel and a couple of hermit crabs there.
The fish is OK, I am not sure why the live rock turns dark especially the side facing up.

 

[jiangmi]

By the way, the live rock were all in light color when i had them from my friend.

 

[NanaReefer]

Please don't be offended but....if you don't have enough time to take care of it then you really should reconsider this commitment. Because it is a commitment! A big one!!

 

[jiangmi]

Please don't be offended but....if you don't have enough time to take care of it then you really should reconsider this commitment. Because it is a commitment! A big one!!

You are right. However, I did not know it before. Right now, I just want to know what is going on and if I can fix it.Thanks.