[icemark]

Thinking of playing around with some bulbs and lighting over one of my smaller tanks, and I am wondering if the actual color and life of the Iwasaki 150watt 6.5k MH is the same as the 250watt 6.5k?

I know the base is a standard on the 150 watt, vs. a mogul on the 250watt. But are there any other differences other than the wattage?

[Steve]

There is of course less heat from the 150 than the 250. I would think the bulb life would be the same.

[Ninong]

icemark ~

I have seen exactly what you are looking for but I can't find it now so you will have to be content with an explanation from memory.

What you are looking for is a spectral distribution chart that compares the 150w 6500K Iwasaki medium base lamp vs. the 250w 6500K Iwasaki mogul base lamp. What I can point you to is a spectral distribution chart that compares the 250w 6500K Iwasaki vs. other 250w lamps and a chart that compares the 400w 6500K Iwasaki vs. other lamps: http://www.personal.psu.edu/faculty/.../aquarium.html

What you are looking for are his tests of the new 400w metal halide lamps (Part 1) and the new 250w metal halide lamps (Part 3). Each of those articles contains charts showing spectral distribution. You can compare the line for the 250w Iwasaki against the line for the 400w Iwasaki (they're on different charts in the two different articles) and this will show you that the 400w Iwasaki is "warmer" than the 250w Iwasaki. These charts are a little hard to read because he has different colored lines to represent the half a dozen different lamps that he tested superimposed on each chart. Anyway, you can get a pretty good idea.

OK, here is where the memory part comes in. I do remember finding a spectral distribution chart for the 150w 6500K Iwasaki medium base lamp online somewhere, but I can't find it now. If anything, it was a bit "whiter" than the 250w 6500K Iwasaki mogul base lamp. I also remember seeing a PAR measurement for the 150w 6500K Iwasaki (60 PPFD). That is excellent! Can't find that site either. Anyway, for comparison, Sanjay tested the 175w 5500K Venture mogul base lamp as only 20 PPFD, the 175w 10,000K Ushio mogul base lamp as 63 PPFD, and the 250w 6500K Iwasaki mogul base lamp as 106 PPFD--you cannot really accept the one test that Sanjay recorded a figure of 124 PPFD for the 250w Iwasaki as "normal" because he tested this lamp four different times and all readings are around 100 PPFD except that one. I wrote to Sanjay and he told me that you can expect variation of as much as 20% between individual ballast performance, and that people shouldn't get too hung up on a single ballast/lamp test result.

You know something, I believe someone may have posted stuff on this 150w 6500K Iwasaki a few weeks back when they posted a thread about the new "50,000K" Iwasaki. I believe a couple of the pics showed a combination of the 150w 6500K Iwasaki with the new "50,000K" Iwasaki. Anyway, see if you can find that, it was on here and Reef Central, I think. But I don't remember any spectral charts in that thread or the links.

Ninong

[icemark]

Thanks Ninong, yeah that was the idea I was looking for. I haven't had time, but I think I will have to do some big searches and see.