It's not just more juice, it's the measurement of useful light energy for your plants. Marineland advertises their product in lumens, lumens are the amount of visible light being produced. I mean the thing is called, "double bright" for a reason yea it's pretty bright. But just because it's bright to our eye doesn't mean its emitting the correct spectrum that plants require. The watts per gallon rule and PAR score is not all that matters.
For example :
I purchased and quickly returned the single bright marineland fixture last year, again for a non planted tank. The light had SO much green and yellow light spectrum that it looked like the exorcist puked in my tank. The double bright has less green/yellow visibly to our eye in it but it still does have a high amount of unusable light spectrum being given off. You need to find out the PUR rating of the Led's in the fixture you want to buy. I am not sure I have ever been able to even find the PUR for the double bright mainly because Marineland doesn't want us to know or just doesn't care since the light was not made for plants. PUR stands for photosynthetically usable radiation. "PUR is that fraction of PAR that is absorbed by zooxanthellae photopigments thereby stimulating photosynthesis". It is very important otherwise your just wasting energy each month powering a light fixture where your plants don't use half the light given off.
Our plants are green because they are bouncing green/yellow light off their surfaces since it's unusable light.
Can you grow plants with it, sure. Is it the best option, obviously not. Marineland does make a planted tank version of their LED strip if you like the looks better. Personally I wouldn't go out and buy a fixture for plants that was never meant for sustaining plant growth in the first place. It will just be a headache in the end when your plants don't flourish as we all dream about.
If your wondering I do have a planted tank. I use TMC Growbeam 1500 Ultima tiles on it. I have had amazing growth rates and results with this product. Yes it comes with a price tag, I spent $600 or so on two tiles but they have very good PAR and PUR ratings and are running some of the highest rated diodes called "CREE XB-D". They do have less expensive strips and tiles with the same type of LED's for smaller tanks, just less LED's. The nano tile is about $110. Not bad at all!! Americanaquarium sells them, check out their site.
Last edited by Fiftymeatballs; 08-04-2013 at 05:15 PM.