Lumens to make medium light?

[blert]

Anybody know approximately how many lumens would be needed to make my lighting "medium"?

I currently have 310 lumens at 12" via LEDs on a 20" tall tank. My anubias and banana plants are showing new growth. The anubias has nearly doubled in size in a little over a week. I want to put more plants in but the ones I want are mostly spec'd at medium light. Am looking at maybe a four CREE LEDs DIY setup but that is expensive. I can get cheaper strips at 450 lumens each (6500k) for about 20 bucks.

 

[aqua_chem]

Lumens is a measure of light perceived by the human eyes. It has little to no consequence in a planted tank.

plantedtank.net had some DIY CREE LED projects done awhile back with PAR data, you might track down that.

 

[blert]

Ah, I see. I'll check that site out. Thanks.

 

[aqua_chem]

Here's the one I was referring to, plus another:

DIY LED for 90cm/36 inch 48 gallon tank -FINISHED! Pics/PAR levels on page 2

DIY cheapest CREE XPG LED fixture for 55 g

First one has PAR data.

 

[BigJim]

aqua chem is right. Lumens are a poor metric for this purpose. When I was designing my LED fixture, I started with a lumen comparison, simply because I didn't know where else to start. The math was telling me I'd need something like 25 Cree XR-E 3W LEDs over a 20H. I've seen other much larger planted tanks do well with fewer than 25 XR-Es, so I knew this was wrong. I settled on ten XR-Es over my 20H and I can grow anything I want in that tank. LEDs pack a lot of punch.

 

[blert]

Nice thanks. I found a good place to buy the CREEs so I think I'll go ahead and make a couple of small lights.

25 on a 20L would be a ton of light. You could probably grow corn in that.

I think I'll go with four XP-Gs at 6500K with 40 degree optics. Two on each side of my current light fixture. Liveaquaria says banana plants are medium light plants and they seem to be doing well with my standard lighting so that should be enough without overkill. I can add more later if needed.

How is the water resistance of those LEDs? I plan to put them inside my current hood affixed to a couple old ram heat sinks I have lying around.

 

[BigJim]

I haven't had any problems with the LEDs and water. Mine are mounted exposed to square aluminum tubing. I have a glass top on the tank, but I slop water on the light when I'm aquascaping and I haven't had any issues.