lighting under sand

[wasabi]

i just installed my refugium under my tank. i have 96 watts pc on my 20 gallon refugium. i have a 6 inch dsb. the lights are lighting up my sand from under the tank. the bottom is glass and is exposed to the light . will this have an adverse affect on my sand bed? should i try and cover the bottom glass?

 

[jmeader]

I doubt the light will have any real effect on the DSB. It won't penetrate very deep into the sand. Maybe about 1/16 of an inch.

 

[danmhippo]

With DSB, we are trying to create an anaerobic (lack of oxygen) area underneath the sand to encourage anearobic bacteria to colonize and help in denitrification of your NO3. Lighting up the bottom of sand will encourage green algae to develop and starts O2 production in the bottom zone, which defeats the purpose of creating the anaerobic zone. The end result would be continued production of NO3.

Yes, you will have to either paint the bottom black or to block the glass so there will be no light to shine on the bottom of the DSB.

 

[wasabi]

thank you. i knew with a plenum the bottom several inches needed to be completley dark. i wasnt sure of the sand bed.

 

[jmeader]

<BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><HR>Originally posted by danmhippo:
<STRONG>With DSB, we are trying to create an anaerobic (lack of oxygen) area underneath the sand to encourage anearobic bacteria to colonize and help in denitrification of your NO3. Lighting up the bottom of sand will encourage green algae to develop and starts O2 production in the bottom zone, which defeats the purpose of creating the anaerobic zone. The end result would be continued production of NO3.

Yes, you will have to either paint the bottom black or to block the glass so there will be no light to shine on the bottom of the DSB.</STRONG><HR></BLOCKQUOTE>
I thought about that possibility and you might be right. But I don't think that green algae could get started in an area that is already anaerobic. Anyway it's not that much trouble to cover the bottom. Duct tape has worked well for me in keeping my plenums dark.

 

[[email protected]]

I assume your suggesting painting the outside of the tank. Won't light get to the bottom through the sides of the glass. How important is it to have total darkness. I'm concerned because I'm setting up a plenum. Do I need to put some black garbage bags inside the tank to totally black out the bottom?

 

[Anonymous]

Reefcrab, we used black PVC panels and black opaque silicone caulking.