We would like to thanks Mammoth Tent company for providing us a grow tent for this article.

Disclaimer 1 : For our English readers, we beg your pardon if you stumble on some broken english (we hope not). That's not our mother tongue, so please bear with us. ;-)

Disclaimer 2 : You most probably can't read our "code of conduct" as it's all in French. But let me summarize the most important point :

We do NOT pretend to have the truth. We do NOT pretend to perform scientific tests. To do so you need some testing materials and time which we don't have. For example, scientifically assessing effects of a nutrient is a job that needs 1k plants and several years. We let this job to government research agencies and universities. We are just hobby gardeners who want to share what we have found with our community.

If you are a total beginner and have no idea what's PPFD means, we strongly advise you to google it and have some readings about horticultural lighting before going on with this article. If you can read french/translate it we have a very good guide here.

Quick market Overview

Lumatek is a very famous UK brand on the french market for their digital electronic grow light ballasts. There are many growers using them with numerous positive feedbacks. Shops often present them as their ultimate product. Gavita is a dutch brand who is a world standard in professional horticulture lighting equipment. Gavita has also a super strong image in the local grower community.

LED market seems very promising however they are pricy products. Technology around LED lighting is evolving super fast. For these 2 reasons most people are either reluctant, or simply cannot afford LED lighting for their plants. But that's clearly the future.

CMH (Ceramic Metal Halide) promise a better/full spectrum for plants, but are currently limited to 300w for now.

LEP (Light Emitting Plasma) are a bit like the CMH case : a more complete light spectrum, being limited to 300w, but on top of that they cost as much as the most pricy LED panels on the market...

HPS (High Pressure Sodium) bulbs is an "old technology" but is still the most commonly used by growers. Their cost is very low and everyone know their good results, specifically in flowering. 600w bulbs are the most commonly sold wattage on the french market.

For all these reasons we decided to give a shot to Lumatek and Gavita products with their Bulb and ballast combos.

A small story

We've been using a 600w Gavita Ballast with a 600w Lumatek bulb for around 6 months in a 12/12 lighting cycle to do many reviews/guides we produced this winter. We took some measurements with our new baby : a new generation quantum meter. In a word : results were amazingly bad/poor. PPFD level were very low for some 600w fixtures. We all know that HPS lamps efficiency decrease over time (it is commonly advised to switch bulbs once a year) however our results were beyond that/particularly crappy.

We contacted Lumatek about it and the british dudes gave us 2 answers :

1. We know about it and we are currently switching our bulb provider to improve our products.
2. You did not used a Lumatek Ballast. Our bulbs are designed to perform best on our digital grow light ballasts.

We won't comment 1. However the second answer puzzled us. A ballast is igniting/powering a bulb. How comes it could affects so dramatically PPFD levels emitted by bulbs ? Frequency something ? Explanation was apparently weird to us.

We therefore contacted Gavita about that and here is their answer :

• This is true that we are tuning our ballast on specific bulb models, particularly Philips bulbs.

So we had to check what was really the best for our beloved plants !

Here we go

We bought both Lumatek and Gavita 600w digital ballast and one bulb of each brand, in a shop, like a standard customer. Please note that we decided beforehand NOT to ask companies about sending us a test sample. Some marketing teams do not hesitate to send "golden samples" to press people that will in the end totally cheat consumers. Those samples are heavily tested beforehand and carefully selected on the supply chain just to get the best of the best. You get it : Journalists review them and get some AMAZING performances... that will be far away from what you will get when you buy the same thing at your local dealer... 

HPS bulbs are known to max their performances after running around 100 hours. We've been asking several experts in horticultural lighting on this. They replied to us that the gap was linear between a freshly plugged bulb and the same one being used for 100 hours. If we notice a gap between 2 bulbs fresh out of the box, the same gap will be noticed after 100 hours.

Test

And today here are our 2 challengers ready to rumble :

As you can see on the pics above, Lumatek ballast is offering us something additional : a 250w set mode. That could be useful if you got suddenly a huge heat spike or a small grow space (and so a 250w bulb available).

We used again our Mammoth Pro 90 grow tent divided in 9 squares evenly. We use the same distance between bulbs and our quantum meter (60cm/23inches) each time and the same very cheap reflector (Stucco). Each couple (ballast and bulb) ran for 10 minutes so that light intensity was in a stable state (both ballasts automatically dim up light at start). Here are some pics of the setup without and with the Mylar around :

Note that if you switch to a better quality reflector you're gonna get higher results. However our goal was not to test reflectors but just the ballast/bulb combo from Lumatek and Gavita.

We tested first Lumatek combo (Lumatek ballast/bulb) then Gavita one. We then crossed items : Lumatek ballast with Gavita Bulb and Gavita Ballast with Lumatek bulb to see if our results were being impacted more by bulbs or by the ballast itself. Measurements have been done on the same 9 different spots (mimicking a 9 plants setup) and we calculated the average. Please see our results below :

The Lumatek combo gave an average 859 µmol m-2 s-1. Gavita combo provided around 100 more µmol (944 µmol m-2 s-1). Gavita combo performed best.

Conclusion

When we crossed ballasts and bulbs we quickly realized something : Ballasts don't have a direct impact on the amount of light being produced for plant photosynthesis. However bulbs do have a major impact. With the Lumatek or Gavita ballast, one bulb will almost perform the same.  We found a ridiculous 37 µmol m-2 s-1 gap. If we look more in details we see that for the 9 measurement points, the same bulb was performing similarly whatever the ballast used.

There are 2 minor differences between Lumatek and Gavita ballasts :

• The way they look : Lumatek got a more bling bling style. You love it or hate it.
• The 250w settings on the lumatek one (which does not exist on gavita model)

About ballast performances : good news for Brits and Dutch, both models are performing very well evenly. Hortinews is therefore recommending them both.

Concerning bulbs there is a clear performance gap in favor of the Gavita bulb. 9% extra luminosity for our plants is roughly the equivalent of an additional 150w Compact Fluorescent Lamp (CFL). On a price level, Gavita bulb cost is around 10€ below the Lumatek one. This price gap is probably due to the magnificent Lumatek packaging (round/protective foam). But you do not buy a bulb for its package.

Between the two, Hortinews would advise to get Gavita SE 230V bulb : it's 10€ less pricy and performing 9% above the Lumatek equivalent.

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