What size Refuge light for a 20 gallon sump?

[mikeguerrero]

I'm currently running the mini coralife 18 watt fixture; they are two bulbs in there at 10,000K. It's centered over a small patch of cheato that I purchased 3 months ago. The light is sitting on top of a 20 gallon tall sump.

The cheato rest exactly 10.5 inches away from the light, since the sump is really tall I have no way of bringing the cheato higher or the light lower.

My question is, what power do you recommend over this small patch that I have? What fixture is out in the market that I can buy?

I have 24 inches across, but only really need 15 inches of contact area, the other inches would waste light, shinning down on my block sponge and return pump.

Anyone with experience please make a suggestion I really need to help to control my nitrates that are excessively high at about 25 ppms.

I've already started the water changes...

Thanks,

Mike G

 

[skipm]

Macros generally grow well under almost any light. If you want to continue with the fixture you are currently using thats fine but I would personally go with a lower K bulb when I replaced them. I would go with something like these mainly because the color temp is closer to sunlight: http://nanotuners.nanocustoms.com/nanot ... ucts_id=47 . There are alot of people that use a clamp on light fixture and use the screw in PCs for a refugium.
How high is the flowrate in your refugium? I have heard that if its too high then nutrient export can be slowed down because the macro has a hard time taking the nutrients in before they are pumped back to the main system (I have no direct knowledge of this but I recall reading it somewhere). HTH, Skip

 

[Dickie52]

I have 20 gallon fuges under 3 of my tanks and I run 2 65watt 10,000K pc's over them and have Cheato coming out my ears.....

I agree on the flow...the slower the better.

 

[aromano]

The algae will grow in low-lighted conditions, less than a watt per gallon, but four are probably near ideal. I am using the same 18W CoraLife fixture that you have and the macro has been very healthy, and growing rapidly lately.

It seems like the lighting is not such an important factor compared to water flow, which the algae seem to like the water to flow slowly through the fuge in order to be able to properly absorb the nutrients in the water.

I am currently running the lights 12hrs a day in an invert cycle from the main tank, but I am actually considering leaving the lights on 24/7 to optimize their use, avoid the reproductive stage of the Caulerpa going sexual and help prevent vegetative degeneration. By running the lights 24/7 also helps reduce diurnal fluctuations in pH, and increase dissolved oxygen in the water.