Try substituting a Phillips Mastercolor CMH lamp. It runs on a 400W HPS ballast; it has a wonderful spectrum with very heavy blue and violet component which will keep your plants short stocky, and it also has tons of red and far red, which chlorophylls love to use. This lamp is about 60$ + shipping.
Do not be fooled by the lumen rating, lumens are what people see, and the eye is most sensitive to yellow light. This lamp will nourish you plants perfectly. As an alternative, you can use a Hortilux 400W lamp which has an enhanced spectrum in the blue band. It just sounds very much like your plants are not getting the blue light they need for synthesis of chlorophyll - without blue light, the plant cannot make chlorophyll, and this will cause the growth problems you describe.

Be sure to get the horizontal lamp

Here is a link that might be useful: Phillips mastercolor CMH lamp vendor

and is in the flowering/fruiting stage, then switch to a pure HPS lamp, which is unbeatable for flux
of photons: By this time the plant has a good supply of chlorophyll, and has switched its metabolism to storing up food. Don't worry about the strong yellow peak, by now the plant has a huge supply of carotenoids, which will capture the yellow photon, turn it into a high energy electron, pass it on over to the chlorophyll, that converts NAD to NADH or something, and turns this into sugars. In my experience, the GAVITA lamp or similar "reflectorized lamp" works the best (from HTG supply), because of the engineering of the built in reflector, ALL of the light goes DOWN and the plants just LOVE IT!!! :)
Sativa.

Thanks,
I will look into getting that light. I had not completed the reflector when I installed the light. I may have had light escaping out one end. I did that yesterday. It just seems as if the light has less intensity than a year ago when I purchased it.

Also, the grow area under my light is about 3ft x 4ft. Should my setup be able to cover this section?

U have a 12 square foot area, with 400W = about 35w per square foot which is adequate. For large cannabis plants, I use 50w per square foot, and that results in a huge lush growth of 3-4' cannabis plants. However, for just tomatoes, your light should be strong enough. Make sure your reflector is good, I recommend either a lumen max reflector, or (available on ebay), an adjust a wing reflector. Also line the sides of the garden with mylar; if you have a cheap light meter, you can measure the difference lining the garden area with mylar makes, they say it is like having an extra half of a lamp- use your resourcefulness to imagine how to do this, depending on your setup, for example 1/4" plywood, lined by mylar - depends on your budget, and what you can scrounge. Even cardboard painted flat white would do, if you wish to save money. Sativa.

Coming from someone who actually grows legal plants ;).

The philips colormasters work great. I have one for a 3x3 foot area with 3 bell peppers, 4 celebrity tomato plants, two roma tomato plants, two habenaro, two jalapeno, two banana pepper and one anaheim plant growing.

All are fruiting except the habenaro, but i have a feeling that's because of some other problem :/.

Each bell pepper plant is about a foot high with about 8 bell peppers on each, the tomato's are about 1 1/2 feet with about 12 tomatos on each right now. The banana, jalapeno plants are still about a foot and the jalapeno plants have about 20 per plant and the banana's have about 8 per plant. This light is great.

Thanks again, that really gives me a good idea of what others are growing with similar setups.

"and is in the flowering/fruiting stage, then switch to a pure HPS lamp, which is unbeatable for flux
of photons:"

(L) Thanks for the good words about ceramic metal halide.
I guess the truth will eventually gain over ignorance.

Permit me to say, CMH will outperform HPS even in the
flowering stage. The blooms will take one or two weeks
longer to finish, but the yield and potency will be greater.
That is, provided the plant is less than 2.5 feet tall. For
tall plants, HPS is better because the spectrum penetrates
better (it bounces easier).

By the time the plants do not need blue spectrum for growth
hormones, they will still need UV-B for potency enhancement.

However if you want to customize your spectrum to the exact
stage, the best way to do this is with the Pulse-Start
Metal Halide. The GE Ultra-Max runs both the CMH and the
PSMH; it is the only electronic ballast (I'm aware of) that
can run the CMH. Because CMH requires low frequency output
from the ballast, whereas almost all electronic ballasts
are high frequency. PSMH comes in four different spectrums:

4K for seedling/cutting stage
6.5K for most of the veg stage
4K for the last week of veg

3K for most of the bloom stage
10K for the last week of bloom stage (for potency).

Also the last week you can run the light 20 hours/day.
That way you get an extra 8 hours/day and one week isn't
long enough to revert the plants to veg.

There are at least two good brands of 400w CMH:
Philips at about $60, and GE at about $100 each.
The GE is higher output and almost the same CRI.

Good to see you back lermer, your detailed and well educated posts are much appreciated. Sativa.

john smith, you don't understand, we are looking for
CERAMIC METAL HALIDE, like the phillips colormaster.
The Osram metal halide you showed is o.k. if u only have a regular metal halide ballast, but we are using a magnetic HPS ballast to run a special lamp invented by phillips called ColorMaster and the output is just like the sun!!!
This lamp costs $53 in the link I have already given. If you have a link for a GE CERAMIC METAL HALIDE, then we would be interested in seeing it. Non-brand quality can also be very good, because the Chinese are not stupid, if you pay them they will sell you what you paid for, and they make a really great reflectorized Gavita type HPS which is just as good as the name brand Gavita, because Gavita actually outsources to the Chinese. Please give us a good link, and enlighten us. Also, I bought some really nice high output T8 lamps that are made in China, and come at a really cheap price from businesslights dot com in Indiana. thanks, Sativa. :(

Thanks, Sativa, for your kind words. Now that the
atmosphere is friendly here, I'll probably post more.

Yes, a lot of people hear just "metal halide" instead of
"ceramic metal halide". Huge difference; CMH is about twice
as efficient per watt as MH, about 50% more efficient than
HPS (generally speaking).

The spam filter does not allow me to post a tinyurl,
and the full URL is too long and would break. However
you can access this with little difficulty by googling
"ceramic metal halide" and "GE" and scroll down to the
"retro" bulbs.

My understanding is that the CRI (color rendering index) is
almost as good as Philips, and the output is higher. The
feedback I get is that the GE bulb is better than the
Philips.

GE also makes the only digital ballast capable of running
the CMH bulb. Life Lights sells these, but their socket
fixtures and reflectors are inferior. GE makes the ballast
with a round aluminum enclosure with universal mounting hub.

I see a couple of places selling these for $97 in the USA online, you first look in the GE site for the part number, and then google the part number for the vendor. Since this is a 20,000 hour lamp, which I think is longer life than the Phillips, and the color temperature is less, meaning there is even more red component, and the photon flux is superior to the Phillips, the depending on how much freedom you have to spend money on your hobby, and how much you like having the absolute best, then go for it. After all, the lamp will probably last for a number of years : if it gives out 10 cents more light per day, then in one year, this works out to 36$ worth of light, so the lamp pays for itself over its own lifetime. Sativa.

Thanks to all for contributing to this topic. I am getting started on my first lighting set up and this has been a great help.
I looked on GE's site and there are several CMH 400W bulbs, the ED37's. Does it matter which one? They vary in color temperature from 3000 to 4200K, otherwise they seem similar. I also found a site that sell the UltraMax ballast for about $260. Is that fair?

Why not use a traditional iron magnetic ballast you can get for $129 from HTG supply? It will come supplied with various goodies that you have to buy for a complete system, and runs the CMH lamp perfectly.

I don't see the spectral distribution graph for the various lamps, but the 3000K will be much more rich in red, and therefore be much stronger for plant lumens. However, in terms of the actual buying when I searched the net, I could only find the 4000K lamp actually being sold from any retailer, for a price of $97. I question whether I would like to spend that much for a lamp, because the Phillips CMH is available for $48 -$53. However, if you calculate that the lamp is giving 10% more lumens, and lasts longer, in terms of putting a little price tag on each photon, the GE lamp might be worth it. Be sure to order the lamp that is designed for horizontal burning. Horizontal is generally
more often used for growing. Let us know what you actually end up getting, where, and how well it works. But an UltraMax ballast is for sure out of my price range. I would much sooner, for less money get a 600w HPS ballast, and run the reflectorized HPS lamp (also sold by HTG, as well as ebay), which puts out 95,000 glorious lumens, all in a beautifully reflectorized distribution.
GE only sells to distributors. Sativa.

A good electronic ballast will prolong bulb life and enhance
it's performance/quality; while saving 10-20% of the
electrical bill. So I think the GE Ultra-Max is worth the
$260.

Concerning the spectrum, I think all the higher wattage CMH
(e.g. 400w) are 4K.

Although higher-wattage HPS are better for tall plants
(over 2.5 feet) generally I prefer CMH. Because of the
spectrum, and also because of the greater number of points
of light (more angles of light means fewer shadows and
better distribution of light). For example, you're better
off with 6 of 400w CMH than 4 of 600w HPS.

Comparing a single 400w CMH to a single 600w HPS is
difficult, depending on circumstances. Generally you will
see equivalent yields, but better quality with CMH because
of the full-spectrum (including potency-enhancing UV-B).
The Gavita self-reflectorized bulb is nice, although
it is possible to find an equivalent or better external
reflector.

The HPS has deficiency in blue spectrum light, which can
cause stretching (high intensity can compensate for this)
and leaf yellowing (again high intensity can compensate for
this). However in the recommended horizontal orientation,
the fringe areas have less intensity. At low light levels,
CMH far outperforms HPS (even, I suspect, the Gavita).

Thanks for all of the help in this post. I bought the Philips Color Master bulb and it has been incredible thus far.

@ lermer
"For example, you're better
off with 6 of 400w CMH than 4 of 600w HPS. "

An interesting point, but it depends greatly on your setup. HID output, in general, is based on a logarithmic scale relative to wattage input. A single 1000 watt HPS creates far more photons than two 500 watt HPS lamps would (though I realize that 500 watt HPS lamps don't exist). If you have created your setup to take maximum advantage of a single light sphere then you may be better off with a single more powerful lamp, let alone the economic advantages of the initial purchase. A little ingenuity can eliminate the advantages of multiple light sources, such as flat-screen training (granted I'm obviously biased towards the method) or other forms of trellising. That said, I have opted to use two 400 watt HID lamps in my own setup as opposed to a single more powerful light, though that has more to do with what I've managed to scrounge up on a budget considerably lower than what you and cannabisgrower are discussing. With the historical proliferation of magnetic ballast HID lamps in industrial environments that is currently giving way to T5 fluorescents I see no reason to spend three figures on any kind of HID lamp, even a 1000 watt.