Hi Scott, Not at all. I have peppers,tomatoes,lettuce, and egg plant right now. I use a 4' vertizontal reflector by sun supply which I love. The more light sensitive plants like lettuce and starts, I put to the outside. This lamp has the energy output of a typical 600w hps bulb. Some say that's only accomplished using a electronic ballast, which are becoming available but are pretty expensive right now. This bulb is a very bright white light. I have done a lot of research about different HID bulbs and like this particular one for several reasons. I really just wanted a bulb that replicated the sun's spectrum as closely as possible, in a HID format. Regular HPS and MH bulbs, even the "enhanced" don't have the spectrum I wanted. Will a HPS or MH do well for indoor grow's, yes they will. To my knowledge,the CMH has a spectrum that is unmatched in a HID lamp. People will use a HPS for veg then switch to a MH for flowering, w/ the CMH that really is not necessary. Assuming the sun has a CRI of 100, doesn't it make sense to get as close to that as possible if growing indoors under lights, for best results? CMH bulbs are rated from 85 to 92 CRI depending on the site you look at. Some will say that CRI is not that important, I disagree. It has more red than a HPS and more blue than a MH. For me it's well suited for every stage of plant growth.

Hi, to make an MH ballast into an HPS ballast, you buy the ballast kit from HTG supply for $55. This is a universal conversion kit. It includes a transformer, capacitor, ignitor, brackets and screws, probably some wire, connectors, a mogul socket, and full set of instructions. You will remove several parts of your existing ballast: you will need to open the case, remove the innards, and substitute them with the new ones. You will keep the case, the plug and cord that you use to plug the ballast into the wall, and the cord that runs from the ballast to your octagon box with mogul socket. All the rest is replaced, so you are left over with an MH transformer and a few other goodies, that you will no longer use, because they have become obsolete. HTG claims they include PROPER INSTRUCTIONS, so I believe them. Now enjoy the beauty of CMH, you and your plants will love it. For 55$ for the kit, and $50 for the lamp, you have a winner that will beat the pants off the AgroMax, AND you will be able to run a reflectorized 400w HPS lamp to boot, should you so choose. You will also be using a 1000W agromax MH lamp, which is a real monster of a workhorse and a beauty of a lamp, for only $70, that's a bargain. I wouldn't change that part at all. It will be generating heat of course, but hopefully your greenhouse is attached to your house, so the heat from the lamp will both keep your greenhouse a pleasant temperature, and also moderate you house heating cost somewhat. Total lumens = 95,000 + 95,000 + 32,000 = 222,000 lumens This is a serious amount of light. What is the square footage of the garden anyway - this amount of light would be good for 90 square feet of vegetative phase growth, and 30+ square feet of cannabis in the flowering phase. Nice. :) Sativa.

Wow, thanks Kimberly for reviving this old thread. Because I have learned some things in the meantime. (Automotive HID lights tend to be more expensive, compared to what's available elsewhere). I repeat my warning to not use the Philips retro-hps bulbs (the CDM400S51/HOR/4K/ALTO; the GE equivalent is CMH400/U/830/R) on the GE Ultra-max e-ballast. Also do not use these on any high or very high frequency e-ballast. There is a CMH bulb designed for use with low-frequency e-ballasts like the GE Ultra-max; the SPXX. However at present is available only in vertical orientation (horizontal is recommended for various reasons). Ceramic arc tubes (like those in HPS and retro-hps CMH) were designed for use with magnetic ballasts and have a stable arc stream in that case. However if subjected to high frequency electronic ballasts the arc stream is unstable and this heat-stresses the bulb. This explains Shrubs' comment that electronic ballasts run the bulbs hotter. This is not just because some (like Lumatec) slightly over-wattage at 1050w. The instability in the arc stream heat-stresses the ceramic elements, causing premature failure and leakage of heavy metals including mercury. Eye Hortilux is the premier manufacturer of conventional horticultural lighting. They published an article in the October issue of Maximum Yield magazine. They point out, HPS and MH bulbs are not suited to high-frequency e-ballasts (with frequencies between 30,000 and 45,000 cycle per second). Which explains the high failure rate and increasing number of lawsuits. For the article, go to maximumyield.com and click unto "Download MY". Then scroll down to the third section of October 2008. Notice, old-style MH are also not compatible with e-ballasts. Even though they are not using the glued ceramic arc tube, the quartz can still rupture and in any event the instability creates a heat stress (shortening bulb life). Sun-Pulse bulbs are designed to have stable arc stream with e-ballasts tuned to them. Sun-Pulse are the only PSMH bulbs designed specifically for e-ballasts. Lumatec, Galaxy, and GE are the only e-ballasts that have been tuned to the Sun-Pulse bulb. There is an electronic e-ballast that is very high frequency (about 300,000 cps) but they go only to 600w and are not readily or cheaply available. As I pointed out in previous posts, this very high frequency is desirable for plant growth because it is closer to natural sunlight. However CMH requires a specific type of low frequency e-ballast (or magnetic ballast). Not all low frequency e-ballasts are compatible with all CMH. PSMH can use either low or high or very high frequency. Because CMH uses ceramic arc tube (which is glued together) it is inherently unstable at high frequency or high wattage. Sun-Pulse are a type of PSMH that are designed specifically for e-ballasts. I recommend the Sun Pulse bulbs over CMH, however they cost more. So for those who cannot afford, use magnetic ballast with CMH. Use the 10K Sun-Pulse for veg, the 3K or 4K for bloom. The Sun-Pulse are even more full-spectrum than CMH. A 400w Sun-Pulse (or cmh) produces far more intensity than can realistically be achieved with fluorescents. The high intensity should be moved quickly in a circle, to cool the bulbs and distribute the light evenly. If this is not feasible (for lack of space or money), combine several 400w bulbs in a cluster and overlap their fringe areas. This simulates how the points in linear fluorescents overlap fringe areas (a 4' line fluorescent tube has an infinite number of points and increasing the number of tubes creates overlapping in more directions).

Thank you for the detailed and thoughtful reply! If I understand you correctly the current T-12 ballast in these fixtures driving 2 T-8 tubes may approach the output of the single SL-15 driving a single tube T-8? If this is the case, my problem is solved. I spoke with Sunpark today and learned one tidbit about temp rating of these ballasts. The rated temp to 4000 hours of service is 45C. For every 10C increase the life drops by half. I do not think my SL-15T s in OD configuration are exceeding that, but based on a very short experiment with the T-12 ballast driving a single T-8 lamp it would be shortening the life of the ballast considerably. Since I can fit 3 of these fixtures into my shelves, using the installed T-12 ballast in normal output configuration I may achieve around a 1.4 ballast factor through the T-8 tubes. I am not hitting the mark for the OD SL-15T, but I am not off by much, and I save the cost of the additional ballast. The person I spoke with at Sunpark seemed to think that running a T-8 tube with the T-12 ballast in normal configuration would actually exceed the T-8 in an OD configuration with the SL-15T. I do not see how that could add up, but perhaps he did not understand what I was asking. I also learned that the both these fixtures actually have Sunpark ballasts that are simply re-badged by the manufacturer of the fixture itself. Apparently Sunpark is no longer going to sell ballast to them, though they will still be available to consumers on the Internet from Sunpark direct. I think that for now at $9.00US a pop I may have to stock up on these in case I keep getting plants and do not finish the planned CFL fixtures.