Is 500 lumens a lot for a 20G Long?

[sen5241b]

Is this bulb good enough to put coralline on rock in a 20 Gallon Long?

see here:

[ame=http://www.amazon.com/LED-Standard-Cloning-Vegging-1313bu/dp/B003MWIC4Y/ref=wl_it_dp_o?ie=UTF8&coliid=I11J4F3B9VIH15&colid=1DIXGHF8XO4HD]Amazon.com: High Power PAR38 All Blue 42 SMD LED Grow Light with Standard Screw Base for Cloning and Vegging 110 240 Volt, 1313bu: Patio, Lawn & Garden[/ame]

 

[Bifferwine]

I have no idea! Hopefully someone with LED experience will chime in!

 

[sen5241b]

Yeah but I thought lumens was the best quantitative measurement regardless of lamp type??

 

[sen5241b]

I looked deeper at this issue and "lumens" is a very poor way measuirng light. I would say lumens as far as reef tanks go is a worthless measurement.

 

[Northstar24]

Lumens measures how bright a light is 'percieved' to be, or how bright it looks to the eye. I don't think its very helpful when evaluating lights for reef tanks because LED's will have a much lower lumen rating, but a much higher PAR rating. My AI LED's look a lot dimmer to the naked eye, but they're putting out a lot more usable light than the metal halides they replaced.

I've read mixed reviews about the PAR38 bulbs. I dont know the dimensions of a 20 Long, but I'd guess you'd probably want two of those bulbs, or you would want to hang it high above the tank to get coverage. From what I understand though, the Par28 bulbs are light spotlights, so I don't know how high you'd be able to raise it to expand your coverage