HID's, what are the pros and cons for MH and HPS?

[Ian Cameron]

Hi Folks, well after 2 yrs of T5's, I have switched to HID's for the balance of my winter season in the in-ground green house. I have done some research but cannot find any definitive reasons to go with either MH or HPS. I currently have 1000w magnetic ballasts for HPS plus scads of bulbs for same. I am currently running 2x 250W MH on my bio beds with chard and kale, and yesterday put in 1 1000w HPS on my 5X5raised bed growing lettuce, kale, chard, carrots and mustard greens. As you can see, its all green stuff except for the carrots which were an after thought, but growing nicely. So, the question is; should I be running HPS over the greens or move to MH?

I know if I go to higher output MH I'm going to have to get different ballasts, but considering the costs for digital ballasts it sort of makes sense to go that route if MH are required for greens.

This is a pilot project for a GH this far north, and I would like to give it an honest try. So far, so good as far as heat etc. Its just the lighting that gives me cause to think hard about the costs around expansion, if it happens.

Any advise would be greatly appreciated on this, as many others besides myself want to see this succeed.

[Vlad Jovanovic]

Since you've probably already done some basic research...I'll skip all that and just say that unless you are growing "medicinal herbs" you might be better off with MH. My plants have always been more leggy using only HPS over MH. 

And again, unless your growing medicinal herb, your edible fruiting flowering cultivars will have no problem both fruiting and flowering under MH light. Most commonly edible fruiting vegetable cultivars do not exhibit photoperiodic traits...All that "you need HPS for flowering" stuff is for MJ growers...not people growing food. 

I just snapped some pics of these peppers and tomatoes for you...all grown under MH light...

Cayenne...

 Jalapeno...

 Habanero...

Some young tomatoes, starting to flower with a few tomato fruits already forming...

 Using MH not only benefits your greens, but when growing indoors under vertical height constraints, MH will tend to give you shorter stockier, sturdier plants..instead of the often lankier results you get with using HPS. I'm using MH over our aquaponics system(s) too. The 50 gallon grow beds are set at about waist height, so the plants hit the ceiling pretty quickly. MH helps to mitigate this somewhat (along with proper pruning)...Man I miss my big tall 16' high greenhouse :)

MH bulbs also put out a bit more heat...to the consternation of many 'indoor' growers, but that heat is useful in a cold weather greenhouse.

If you should need any equipment, bulbs, ballasts etc...feel free to visit our web site. I'm running a Christmas sale on all things lighting related...There's a bunch of stuff I haven't yet put up on the "lighting sale page", so PM me if you want something specific, but don't see it there. 

http://stores.atriaaquagardens.com/lighting-sale/?sort=featured&...

(I don't care if you buy anything from me or not, just thought I'd offer. I don't sell any cheapo "off-brand" ballasts, and all my digital ones come with a 3 year warranty...So I'm sure you could find less expensive (different "Amazon only" type brands on the net)...

Hope some of that helped 

[Ian Cameron]

Vlad, that's awesome!!! Kinda makes my setup look puny. Ah well its still in the experimental stages. Well, it looks like MH will be the thing to use. I will check out your site! All my HPS stuff came from a now defunct ahh..  herbal setup, and I got it all for virtually nothing. One of those "I'm outa here, you can have whatever.." type deals.

Anyway, to pick your brain a little more, should I go for multi wattage ballasts and just buy appropriate bulbs, or can I use smaller wattage bulbs with 1000w ballasts? I'm just looking for the most cost efficient way on a very limited income.

Again, thanks very much for your help, it's greatly appreciated!!

[Vlad Jovanovic]

Hi Ian, 

I would go with a dimmable ballast over a dial-a-Watt ballast. They are not at all the same thing. With the "dial a Watt" type, you set the ballast to a particular wattage (say 600Watts, then need to use ONLY a 600Watt bulb. If you change the Wattage selector on the ballast (say to 1000Watt), you need to REPLACE the 600Watt bulb with a 1000Watt bulbs.

While with the "dimmable" type ballasts you don't need to change out bulbs. Say you have a 1000Watt dimmable ballast, you need to use a 1000Watt bulb...but you can then run that same 1000Watt bulb at 60%, 750%, or 100%

So I prefer these dimmable types over the Dial-a-Watt or Select-a-Watt types.

Make sense?

Here are some pics from a few months ago. This pepper plant was grown using the very same MH bulb in the same space as in the pictures above...(these pics below are there just for fun...the cayenne got crazy big, ran into the ceiling, then took a left-hand turn. This one was grown in a 5 gallon bucket on the floor, using nutrients that I formulated from individual reagents [no store bought hydroponic nutrients were used] The 3 pictures below of of the same plant...I've since removed it and replaced it with the smaller young plants pictured in the previous post...

 

 Hitting the ceiling...

 Top of the plant... 

[Ian Cameron]

Yup, that makes sense. Thanks. I checked out your store and the $$ look good. Too bad I have to put up with the $Cdn against the US$, plus freight. Is that the real price for the API Master test kit? Up here they are $65.

My daughter is slavering over those peppers,not going to hear the end of this for a while (smiles). Already its "when are you going to try hydro as well as aqua......", well you get the picture.

Thanks again!!

[Vlad Jovanovic]

Yeah, that's the real price of the API Master test kit. Wow, $65CDN is pretty expensive! (even at the 0.86 exchange rate).

Probably VAT (or GST...or whatever other taxes they've come up with recently...Serbia was the same way), and import duties I imagine...

No problemo :)

[Jeff S]

Are fluorescents OK to use for seedlings if they are kept close?  

[Ian Cameron]

Jeff, I've been using them exclusively for 4 yrs. with nary a problem. Just keep them within 8" and you should be fine. Don't forget to use a fan.