Seedling starter light T5 or metal halide

Right folks I need a new t5 seedling light as the one I have is roasting hot
Even the shade roasting so I have seen online for the same price as a t5

A metal halide 150watt reflector setup it claims to be better than T5 and not as hot.would this be a good light to get it's only to start seeds also I was thinking
I could use it along with my 400 watt hps for extra light in flower but I am unsure
If it would work .?

Any help would be great thanks in advance

To start seedlings off I would go with a fluorescent over a MH any time,even the smallest MH.I have to say though I've never grown or started plants off with T-5,heard a lot about it though and have never heard of any heat issues with them,I imagine that is the subject here.I like my cheap 4 lamp T-8 fixtures to get plants off the ground so to say.I keep the tubes no farther than 1/4 inch or so the whole time I use them.and usually grow my seedlings to the third or even fourth node with them.To get such healthy compact little 3 or 4 inch bushes with a MH would require some good heat control for the lamps,it's just a lot easier and more effective using Flo tubes at this point of growth I think

Ok thanks floridian I am going to phone shop tomorrow and ask because it says on his site the m/h
Setup runs a little cooler than 200 watt cfl or T5

I don't put plants under a metal Halide till about the fourth or fifth node as the normally find it too intense

There is nothing wrong with T5 or MH for seedlings; I have used both personally. With the MH, I would start with the light about 4 feet away (although I was using a 400w), and lower it down as the plants begin to grow; where the T5 i just slam it down as close as I can once they are out of the dome. What I would like to know is, why is your T5 so hot? I can easily lay my hand on any part of my T5, and only the bulbs themselves are uncomfortable to touch, but they are not extremely hot. Now if your having a heat issue due to a lack of ventilation, going from a 200w light to a 150w light, it will save you 50 watts worth of heat; but I doubt that will solve any significant issues. The biggest reason to go with MH is that you will be able to veg larger plants under the MH, if that is a factor. But if larger plants are your desire, go with a larger lamp, say a 400. Just be prepared to get that light far away from seedlings for a couple weeks.

Hey OldPhart I think my light is faulty it's not T5 but 4 55watt pll bulbs it's reflector is burning hot
And feels unsafe hot,hence why I need new light I phoned the shop guy about sun king mini 8 150watt
He said I would get better results than the light I am using at the moment but I would need too have 150watt 2ft above seedlings he said the metal halide would keep plants smaller with metal halide
And said the 150watt could be used as supplemental light next to my 400hps if I wanted...

FreeUrMind said:

Hey OldPhart I think my light is faulty it's not T5 but 4 55watt pll bulbs it's reflector is burning hot
And feels unsafe hot,hence why I need new light I phoned the shop guy about sun king mini 8 150watt
He said I would get better results than the light I am using at the moment but I would need too have 150watt 2ft above seedlings he said the metal halide would keep plants smaller with metal halide
And said the 150watt could be used as supplemental light next to my 400hps if I wanted...

Click to expand...

Can you just pull out 2 of the 4 PLL tubes?
A 55 watt PLL is basically a 4 foot T5HO bent in half.
OldPhart hit the nail on the head: 25% less watts = 25% less heat. Your shop guy is right that 150 watts of MH will probably make less heat than 220 watts of PLL.
You could just save yourself some money and disable 1 or 2 PLL tubes.
Need to take into account the shape of the reflector and how air will flow around a new fixture. T5 (and presumably PLL) fixtures are kind of bad at trapping heat because they are basically a big panel. The benefit is more even distribution acrosss a flat canopy vs a single point light source which almost always suffers from a hotspot in the middle.

Can you do anything about the airflow in this space?

Hi Raho there is only 2 x bulbs in it and had a 12ins fan blowing across the bulbs.
It's very old light and maybe broken because the heat from it is very warm I had it
6 - 8ins away from tops of seedlings

Have you thought about changing the lamps in it? As lamps get older they tend to run hotter, changing for fresh lamps will probably solve your elevated heat issue.

As for MH or T5, you'd be surprised how well seedlings will do under a 1Kw HPS. Lots of growers sprout seeds under 12/12 HPS lighting, with excellent results. The key is to maintain a comfortable growing environment at the seedling level.

The more light, the sooner the seedlings will need nutes. With full strength lighting, you can take a 3 day old sprout and have it happy with full strength nutes within 10 days.

I have to admit I'm cornfused.You have to keep your flourescents 6 or 8 imches above the seedlings?That totally negates the reason for using them.The T-8's I start my seedlings or brand new clones under are never more than 1/2 inch above the tops for the first 10-14 days,I make sure of it so I have to watch them daily.I have had them grow into the lamps before,especially clones but with zero harm done.I honestly don't know if the flo's you're talking about are the compact squigilly motherfuckers I would not use those,with a 4 ft tube you can line up 9 or 10 seedlings or new cuts along the entirety of the tube.And like I said heat is not ever an issue,they can grow right into the glass and if you catch it the next day,no harm done at all.You've got some hot fuckin flourescents going there bro if they aren't tube flo's,you need to get with 4 ft tubes.I used 4 ft T-12's for a hell of a long time before I started with the T-8's,I doubt T-12's even exist anymore.I never had a heat problem and always grew the tightest node compact 4 inch plants possible.Thats why I like flo tubes over MH lamps no matter the wattage,there is no stretch period when a flo tube is sitting a fraction of an inch off the top of the plant.Even a lightweight MH like 250 you have to keep it up above the plant a foot or more for temp reasons normally,and the plant is going to stretch towards the light.No stretch with flo tubes,just tight nodes and mainly horizontal growth.With a 4 lamp 4 ft fixture I would put the seedlings/clones in the middle of 2 lamps and have 2 rows totallying 16-20 plants

Just recently switched from T5's to 600MH. Seedlings, clones etc are loving it with lamp at 36"
Total lumens and lumen per watt are far higher with MH. But the switch was due to relamping costs. We were replacing T5's every 180 days @ $10 per bulb.
That's twice the cost of MH replacement.

Expected longer internodes with MH but the opposite is true. Very tight thick plants.

• Last time I started a bunch of seeds, I did it under a 600 MH and I got excellent results.
• If I were starting from scratch, I'd run 315 CMH. Phillips Agro 3100. Best spectrum on the market.
• T5HO's make a lot more heat than T8s.
• HPS puts out a lot of it's lumens in the IR range, operating basically as a heat lamp.

OP, please tell us about your environment.
Specifically, LxW dimensions, headroom and cooling capacity/air circulation.

Your current plan is to replace 110 watts of PLL with 150 watts of MH and you expect less heat . . .
The guy telling you to change your PLL tubes may have the best advice. Those bulbs can be had cheap.

I use T5s. I have 4 x 200w 4ft 4 tube fixtures in my nursery/veg/mother room all set up in strategic locations as I use shelving for seedlings and clones. I'm OS ATM so I can't post photos, but it works a charm. From 400w T5 (4100k blue light) veg they go under a 600 DE Gavita, which I crank up over the course of flowering to finish at 1150w by week ten.