[Wet Thumb Forum]-PC/CF Lighting for planted tanks

[nino]

Roger,
I have this one question and yet couldn't really get the answer straight. What is the difference between commercial bulbs and aquarium product bulbs ? Example, Philip has daylight 6500K bulb and so do many aquarium bulbs out there but Philip price is much lower than specialized bulbs. Would the more expensive bulbs be at least slightly better than the commercial bulbs (for plants)?

[Roger Miller]

ninob,

I can't possibly compare lights on the basis of color temperature alone. There is no information to go on. Two lights with the same kelvin rating can be completely different in every measure that really matters.

Some of the lights sold for aquarium use are repackaged versions of lights that are made for commercial trade. When they are sold on the aquarium market they are substantially more expensive. The best example I know of is one of the Hagen tubes (I can't remember which -- read Ivo Busko's article in the AB library to find out) which is actually nothing but a repackaged cool white. Of course it sells in pet shops for 5x what it costs at Lowes.

Locally I checked the prices of some bulbs at my LFS and noticed that they were Philips bulbs, so I found a Philips distributor and bought from him. I commented to the distributor about the cost of lamps at the pet shop and he told me that the pet shop bought the lamps from him at his retail price and then doubled the price for resale.

More generally I have never found that companies selling lamps for aquariums have any lock on good bulbs. They don't know what your tanks need or even care. They are selling what they can market for the biggest return. There are a few lamps that are exceptions -- the Triton lamps, for instance. Otherwise there are very few lamps available in the aquarium market that can't be replaced by better lamps purchased for less in the commercial lighting market.

In fact, if you *really* want a good lamp you probably won't find it in the aquarium market. The C50, C75 and PL-L950 lamps are great examples and they are made and marketed mostly for display lighting. If you're interested in metal halide lamps for planted tanks then the best lamp I've seen for sale is a GE (I think) bulb sold for commercial display lighting.

I stopped buying "aquarium" bulbs a long time ago. Too many of them are rip-offs. The ones that aren't might fill a real nitch in the aquarium market but could be replaced by excellent (but not identical) commercial lights for half the cost.


Roger Miller

[nino]

Thanks Roger. That's what I thought. Too bad I use PC on all ny larger tanks. The smaller ones, I use ODNO but have problem looking for any short daylight commercial bulbs.

[Roger Miller]

ninob,

What kinds of "short" lights are you talking about?


Roger Miller

[Oleg]

Hi Newt and all !!
I were looking since 2003 for PC lamps with a similar spectrum to Gro-Lux or Aqua-Glo. It looks like we have to wait a bit more when manufactures decide to make them. For now I am using Coralife 6700K for my two tanks:
1. 30G tank - 2x65W
2. 25G tank - 1x65W
My plants grow ok but they did better with Aqua-Glo/Sun-Glo setup.
I ordered three Sylvania PC lamps 55W - 3000K, 3500K and 4100K. Expecting them next week.
There is much more red in the Sylvania 3000K than in 6700K I have. This red is in 610nm not 660nm as in Gro-Lux, but there is no better choice anyway. I am thinking to set light as following:
1. 30G - 1x65W 6700K + 1x55W 3000K
2. 25G - 1x55W 3500K (or 4100K - depending of how it looks)
As soon as manufactures make PC lamps for plants I will change this set up.

[Newt]

Hi Oleg,

I spoke with a Sylvania rep about two years ago regarding making a CF/PC version of the GroLux and they have no plans to make one. Perhaps if enough of us emailed them they may think about it. You can get GroLux bulbs real cheap at
"]www.goodoffices.com,[/url] but you need to buy them by the case of six. CF/PC bulbs are not quite there yet for plants. The ESU-Coralife bulbs have a lot of big emissions in the green and yellow spectrum like the JBJ 6500K bulb. I dont recommend the Hagen bulbs, the emissions are not very strong. They skew the spectral output graph by making it look like high emissions. This website has an article about bulb comparison. Go to AB Reference, Library, Lighting&Equipment and find the article on Light bulb comparison by Ivo Buska. It has a lot of spectral graphs for many bulbs - an excellant article. Pay attention to the emission rate listed on the Y axis.

You can also try www.lighting.philips.com and their importer www.aamsco.com. Other sites to purchase bulbs are www.ahsupply.com (they have a 55 watt, 5500K, 91 CRI bulb for ~$19.00 US), www.brite-lite.com (Canadian site but must buy in bulk) and www.hellolights.com. Hellolights say they manufacture their own bulbs but I dont think so. I think they are ESU bulbs. There are not too many manufactures for fluorescent bulbs.

Remember, like Roger says, you really dont need a 'plant' light if it has strong enough light in approx. the right spectral output. You just need to avoid those that have hugh amounts in the green and yellow areas. A bulb with a high CRI will have good enough emissions across the spectral output mimicking sun light.

Good Luck.

[Newt]

I thought this might be of benefit to some.

[Newt]

I got my Philips PLL-950 bulbs today. They could use a little more emissions in the red and higher up in the red, too. But they were a good price.

[imported_trilinearmipmap]

I am a little confused about the GE 9325K bulbs, everyone raves about them, according to the Atlanta Light Bulbs site their CRI is only 67, am I missing something?

[Newt]

I looked up the GE 9325K bulb on the GE website. It is product number 45859. It does list it having a CRI of 67. BUT it has (Ra)in front of the CRI. I have no idea what this refers to or if it makes a difference.