Newt

Here is the visible spectrum (for humans):



Here is the output within the visible spectrum for the GroLux:


The Philips 6500K Day Light bulb (available in T5 48' linear at Home Depot et al) will balance out the dim purplish color when mixed:

fishstein

Have you seen how the Philips 6500K Day Light T5 looks combined with the GroLux T5? Or have you seen how these same bulbs look mixed in T8 or T12? Hate to go just by manufacturer's claim. Some lights throw really different color than you'd expect.

How much do those Phillips 6500K T5 bulbs go for at Home Depot?

Thanks very much for pointing this out. I have great T8s, but was trying to find out what equivalent would be in T5 for another tank, and this forum has provided some great info. Now I only wish someone had photographed the same tank under these various bulbs...

Newt

I have used the 40 watt GroLux Std (48") T12 with the Philips F40DX 6500K T12 and it looks great combined. Here is a picture with them in use along with (2) Philips PLL950s 55 watt CFs (5000K).



The T12 cost about $7.00 for two. I forget the price of the linear Philips DayLight T5s as I have not purchased them.

Newt

Defdac,

I looked into the link/site a bit more on the T5 GroLux and the spectral output they show is not the same as the 'old' standard GroLux, or at least from what I could tell.

I have emailed Sylvania to see if I can get some more info on this. I will let you all know what I find out.

You guys in Europe sure have a lot more and better accessories to choose from in the aquatic world. Lucky...............

defdac

I got me a $25 Project STAR spectrometer and made a software that converts the spectrum to an ordinary spectral distribuation diagram like this:
http://www.defblog.se/picture/1691.html

It's not completely exact due to the IR-filter in the camera and the fact that the R, G and B-sensors doesn't overlap exactly, but I can check if they are good and within reason.

Big vendors like Philips, Osram etc have good spectral distributions and you can see when they are fairly "good" looking. Smaller vendors like Hagen have very fabricated spectral distributions nothing like you would get from a spectral measurement. Looks like something from a toy store:
http://aquagarden.iespana.es/fotos/aquaglo.gif

defdac

It seems that the lumens output is the value to really question since it's very hard to measure. You need a gigantic integration sphere to fit the bulbs in and then have calibrated equipment to get a good measure...

Newt

No, we can't trust the marketing departments. Especially when they provide a spectral output in % relative intensity and not something meaning full such as watts/5 nm/1000 lumens.

Defdac seems to have lots of good info and being from europe will have much better equipment to talk about and a better understanding of planted aquaria and its needs.

ruki

I have one of those spectrometers. Through the eye, it's very good for determining the presence of a particular wavelength, but of course not so great on measuring the intensity of the spikes. You process takes this to a whole other level. Really neat.

My first problem is taking decent photos. I used a 1:1 lens in my Digital Rebel, but getting the exposure correct is not easy for me.

It isn't obvious what you are doing once you have a properly exposed picture. Are you taking intensity levels via Photoshop and then feeding that to a plotting program?

ruki

What might work for us as a rough estimate is putting a light meter on the bottom of an empty aquarium. You could at least compare fixtures with ~"standard"~ lights.

Doing it the absolutely correct way with scientific instruments is very expensive.

defdac

My Coolpix 4500 have a supermacro-mode making it fairly easy to take a good picture - but I would really like to modify the lens in my QuickCam3000 to be able to shoot good pictures from the project star spectrometer since I have removed the IR-filter from it. That would make the spectral distribution accurate over 650 nm.

I cut out the 400-700 nm part of the spectrum-picture from the Project STAR, reverse it to make the blue part on the left, desaturates it, and then I scale it down to 1x400 pixels and makes an "auto levels".

Then I input this 1x400 pixel picture into a Java-program I've made which extracts the RGB-values and paints a B&W-distribution where black in the original picture is a bar with height 0 and white (255,255,255) is a bar with height 255.