newbie needs help lighting a 55 gallon

[Swimmingorchids]

I literally would not worry about umol/2^s too much which is what I already mentioned.

All LED's these days are powerful enough to grow plants well, something that hasn't always been the case with artificial lighting in the past and exact calculations were needed.

you can place the light as close or as far away as you want



The only thing you need to be aware of when buying LED's is that some sellers will try to mislead you and tell you the amount of watts fitted to the unit - not the watts the unit pulls from the wall - which is usually half that.

I can tell you the 300 watt unit on the last post draws 150 watts. Still good value. Won't have the same CRI value as the lights you were looking at but half the price per watt and decent lights - only reason I wouldn't get those units is because they have noisy fans to cool them

[Ray]

Swim made a good point. Actual watts are important; "equivalent" watts is a useless parameter for plants.

Unlike him though, I wish all lamps had published PPF data, as that's what's truly important, as it represents a quantity of light, as well as a true spectrum. Those two, combined, tell almost the entire story.

BBQ: Don't get sucked in by color temperature, as it's relatively meaningless in fluorescents and white LEDs, being a "corrected" or "correlated" color temperature - one that looks like that black body temperature to the human eye. Also, if you look at true published spectra for white LEDs, the "warmer" CCT's seem to have more far red in them, which is good for promoting flowering.

Here is a great graph showing the relationship between the plants' relative light absorption of the spectrum, and how PAR and the human eye response (lumens) differ from that.

[ColoradoBirddog]

Is there a good way to find out what the actual wattage use would be, as opposed to the "equivalent"?

This might sound odd, but I'd prefer an LED setup that produces heat. We tend to keep the house cooler in the winter, and the 400w HPS I have now does do a good job of keeping my terrarium warm enough.

Maybe I want to look into a heating pad...