Lumens and PAR

[m.lemay]

I just sent an e-mail to pet supply liquidators asking for PAR data and/or spectrum graphs on thier 55 watt tubes. I hope they'll be responding soon. I told them,if they want, I'll post the data here and it could translate to more sales to them. A little bribe never hurt:hehe:

[SNPiccolo5]

Lol! I just did the EXACT same thing! After not responding to my first e-mail, I decided to "put a little extra" into the e-mail! Well, if they don't believe you, they will when they read mine ! Hopefully they have some data...

-Tim

[GulfCoastAquarian]

Pet Supply Liquidators has replied to my emails before, but they take a few days and usually won't trouble themselves with lengthy technical questions. They're not a technical resource, I guess, they're mostly committed to supporting sales - which you can't blame them for.

I'd be very curious to see how plants respond to one of those plant growth bulbs, though. This is the first PC bulb I've ever seen specifically designed for planted aquaria.

[m.lemay]

Pet supply liquidators just e-mailed me back. They said, they doubt that they have any PAR ratings but that he probably could dig up some spectrum graphs for the bulbs and that they'd e-mail me back as soon as he finds them.
I think the bribe worked!!:hehe:

[SNPiccolo5]

They replied to mine as well but said that they don't have many specifics, but will e-mail info to me once they get some...

-Tim

[-bala]

What fluorescent lighting aspect is most critical? Color Temperature, CRI, Lumens or total wattage? I've read that the ideal color temperature range is in the 5000k to 7000k range, CRI greater than 85 and Lumens in the 2000 range.

However I have a single 15 watt 18" GE Aqua Ray on a 10g which is rated @650 lumen and a whopping 9400k color temperture. The water sprite is taking over the tank.

[m.lemay]

Read the first post on the first page of this thread and click on the blue link entitled "A comparison between light sources used in planted aquaria".
All those things you listed are a piece of the answer but the article will "enlighten " you as to whats important for plant growth.

[m.lemay]

The GE fresh and saltwater 9325K 55watt PC bulb has the same signature as thier NO fresh and saltwater bulb. In the article Sam posted in the first post there's a chart showing this bulbs spectral signature. Even though the plot is for a NO flourescent the signature is the same, though probably more efficient, All-Glass claims that it's the same bulb but in a PC configuration. Heres The Plot.
Check it out.

[GulfCoastAquarian]

Hmmm, interesting. More green output than I'd imagined it would have.

Bala, the guidelines you stated for CRI, lumens and color temperature are usually aimed at four foot 40w F40T12 bulbs (the most popular size). There's one I would disagree with. Generally, a high CRI won't have the spectral output a plant desires. The true way to choose a plant bulb is by its PAR, but since that information isn't readily available, indicators you should use are:
1) CRI in the 80-90 range.
2) Color Temperature in the 5000K-6500K range.
3) Slightly less than average lumens output. (Avg 40w tube makes 3000, so 2000 is typical of a plant bulb)

The reason for number 3 is that lux (lumens) is a measure of light intensity, based on a color spectrum that humans are most sensitive to (most sensitive to green). Plants are exactly opposite - they are less responsive to green and more so to red and blue. So a bulb with uncharacteristically high lumens output will likely have a ton of light that we can see, but less light the plants can see.

As Marcel mentioned, all of this information is contained in much improved detail in the article posted in the first post of this thread.

[m.lemay]

Pet supply liquidators got back to me with some info on thier plant bulb. Its not the greatest picture in the world.

55 watt Plant Bulb

[SNPiccolo5]

Hmmmm, not much better in my opinion than the 9325 K, though I'm pretty sure this is the next bulb I would try for my setup...

It seems whenever I look at the curve for a bulb and compare it to the one in the article given on this topic, that the red peak could be at a higher wavelength (I was surprised to see this on this bulb since it has a separate red tube), but if I see correctly, the blue is pretty good on this bulb...

Lots of green output though on this bulb, thats the problem. If the bulb is going to be white, you need only red, blue, and green light to make white, so that explains why green is a high peak in so many bulbs. What does everyone else think?

-Tim

[Anonymous]

You beat me to it. Nice green output to grow plants . . . hmmmmm . . . oh ya! nice green output to grow algae. I never understand why so called "plant" bulbs spike really high in the green spectrum.:fire:

[GulfCoastAquarian]

The green spectrum is just there for us to see the fish. Think of how dim your tank woudl look with only red and blue output (ever look at a reef with actinics and red moonlighting? the fish can sleep in that light.)
If they had little green output, their lumens rating would be nearly zero. Normal bulbs have a green spike easily twice as tall as their red and blue spikes (if they have a concentration in red or blue areas at all). A good balanced tri-phosphor bulb has always been the ideal choice for plants.

[m.lemay]

I think I like the 9325Ks better, they're a little higher in red and blue and little lower on the green output, hence the violet hue they produce.

Marcel

[GulfCoastAquarian]

I really wish I could get my hands on one of those 9325K's. I've got to see what they look like.