Refugium Plant Lighting

[zfunk007]

Hey all.. im starting an 80 gallon refugium for my 400+ gallon system... im gonna have 4, 48" VHO grow lights on my refugium.. and planned on leaving them on 24/7... however some people are telling me that i don't need to leave it on 24/7.. well doesnt that defeat the purpose of a refugium then? Can someone answer this question for me? Thanks.

[mesocosm]

Greetings All !

zfunk007,

If the purpose of the refugium is nutrient export, then 24/7 lighting is an acceptable choice (especially if you're growing Chaetomorpha).

If the purpose of the refugium is to stabalize pH fluctuation, then perhaps "reverse lighting" (having the refugium lights on when the main display lights are off) is the best option.

Having said all that, marine algae do benefit from a dark period (... after all, they call it the "dark cycle" of photosynthesis for a reason ...), and marine vascular plants require a dark period for best overall health. I typically run a 16/8 photoperiod on both nutrient export and growout refugia.

HTH.

[Triterium]

I have tried the grow lights over a fuge before and the growth was terrible. If you haven't already bought the lighting, you may want to consider metal halide or other types of incandescent lighting. Just make sure the bulb is around 4000-6000K.

I light my fuge for 5 hours a day with a 4000K MH bulb. The growth is amazing. I have tried lighting it for longer periods, but didn't see a significant increase in growth rates.

The "dark cycle" occurs 24 hours a day, even when its light.

[reefidiot]

If I recall correctly from my organic chem classes, these "dark " reactions are so named because they are independent of light, or photosynthesis. They still occur in the day or night.

[mesocosm]

Greetings All !

"... these "dark " reactions are so named because they are independent of light, or photosynthesis."

The photochemical events of photosynthesis: "light reactions".
The biochemical events of photosynthesis: "dark reactions".

... a little history ... these reactions were so named because they were discovered to occur ... you guessed it ... in the dark. The researchers at the time were surprised by this. Everyone had presumed that ALL of the chemical mechanisms of photosynthesis were photo-induced. It was only during subsequent research that what is now generally referred to as the Calvin cycle was discovered to be essentially light independent.

I say "essentially" because the energy that drives the Calvin cycle in chloroplasts IS photo-induced ... let's all say "electron cytochrome cascade" ... .

To say that the conversion of CO2 into glucose in plants is independent of photosynthesis is ... no offense ... less than meaningful.


"(... after all, they call it the "dark cycle" of photosynthesis for a reason ...), ..."

Sorry ... that was a bit over simplistic and obscure, with potentially wrong implications ... my bad.