Best Par Rating from 400 watt MH - 4200k - 20000k?

[LSWM]

Anyone know which bulbs have the best par ratings? I've been searching around and I'm finding it difficult to sort through all the information.

I would like to use cheap UltraSun bulbs if possible, and can get 4200k 400w bulbs for $15 a pop. Can't beat that. But I'm looking at the spectral distribution charts from UltraSun and they have the exact same chart for their 7,500k bulb as their 4,200k, at least at 400w. The 1000w charts differ. It's also worth noting the 7,500k bulbs are ~2/3 more expensive.

The tallest peak in both charts is in the green spectrum which will certainly not provide much plant usable energy. The current plan is to run stacked bulbs in a donut. A 600w HPS over a 400w MH. Maybe mixing a bluer bulb with a red HPS may be better, or maybe mixing a redder MH with HPS could be better... This is going to be an experiment of sorts, but I'm looking for any extra info anyone has.

Here's a link to the charts in question:

400w 4,200k
400w 7,500k
400w 10,000k

 

[Miraculous Meds]

I cant help a whole lot with this but I would like to remind people, make sure the bulb is rated for open fixture, and for vertical placement, or u run the risk of ruining the bulb, or worse a fire.

 

[LSWM]

I cant help a whole lot with this but I would like to remind people, make sure the bulb is rated for open fixture, and for vertical placement, or u run the risk of ruining the bulb, or worse a fire.

All these UltraSun MH lamps are rated for use in open fixture ONLY and are universal burn position.

 

[LSWM]

Looking at 1000bulbs.com 400w MH selection it seems there are even cheaper 4,000k bulbs at $9-11 a piece...

 

[Drek]

The old Retro 400w is still good, if you can find one.

 

[Beta Test Team]

Anyone know which bulbs have the best par ratings? I've been searching around and I'm finding it difficult to sort through all the information.

I would like to use cheap UltraSun bulbs if possible, and can get 4200k 400w bulbs for $15 a pop. Can't beat that. But I'm looking at the spectral distribution charts from UltraSun and they have the exact same chart for their 7,500k bulb as their 4,200k, at least at 400w. The 1000w charts differ. It's also worth noting the 7,500k bulbs are ~2/3 more expensive.

The tallest peak in both charts is in the green spectrum which will certainly not provide much plant usable energy. The current plan is to run stacked bulbs in a donut. A 600w HPS over a 400w MH. Maybe mixing a bluer bulb with a red HPS may be better, or maybe mixing a redder MH with HPS could be better... This is going to be an experiment of sorts, but I'm looking for any extra info anyone has.

Here's a link to the charts in question:

400w 4,200k
400w 7,500k
400w 10,000k

Hi LSWM, nice to see you again.

Due to our good talks before I thought you may like to know our spreadsheet will analyze any lamp for PAR (PPF as radiance), as well a whole myriad of other important values.

PAR isn't affected by blue, green and red wavebands, as it treats all wavelengths as equal (non-weighted). What you seem to want is the weighted PAR, which accounts for the effect on photosynthesis by each wavelength, and in that case, green provides about 70% while blue is about 80% and red is up to 100% (relative effect on photosynthesis).

From looking at those three SPDs, the first one is likely to have greatest radiant photon flux between 400 and 700 nm. The last lamp wouldn't be a good choice if used alone, better would be either of the first two. Or, include the third to 'mix' the spectra.

The first two are also likely to have greatest radiant weighted PPF, so should provide greater photosynthetic rates vs. the last one.

 

[xet]

Does anyone have a link to someone who has tried to grow anything above water with a 20,000K mh?