T5ho vs metal halide

[MoeCanada]

Dear Members,

I recently moved my system indoors due to the winter here in canada. I have two growbeds 4 ' x 2.5 ' x 8" and 120 gallons fish tank. I purchased hydro farm 6 bulb 4' t5HO 54w each ( 324 watts total). I was wondering whether to buy another one of the same for my other growbed or buy metal halide 400Watts.

If i decide to go the metal halide way how far from the plants should the light be in order for them to not get burnt but at the same time get good results. Feedback would be greatly appreciated. Thanks

[Yabbies4me]

These may help a little Moe:

http://www.aquaponics.net.au/forum/s...plants&page=25
http://www.aquaponics.net.au/forum/s...+plants&page=3

They are just the tip of the iceberg... that I could pull up quickly coz I remember the recent discussions, but indoor grow lighting has been covered on numerous threads in the past. I think there are even threads specifically dedictated to it, try the search function and you should be able to find them.

I know the high output T5's have been discussed, but I don't think it was that extensively.

Wendy has tried a variety of lighting and appears happy with her new 400w MH light, in regards to plant growth and providing warmth.

Cheers.
.

[MoeCanada]

Thanks Yabs. Do you have any personal experience with T5HO. I would rather ask before buying as both the Metal Halide and t5HO are expensive so i wanna make sure that i buy one time. Thanks

[Yabbies4me]

The only experience I've had with them was a long time ago and I wasn't that impressed with them, but it all depends on what you'll be growing under them. For small leafy greens and herbs etc they'd be fine, but if you'll also be growing larger leafy greens, such as Spinach, Celery etc, or if you're gonna be growing fruiting plants such as Tomatoes, Capsicum etc, then a 400w MH would definitely be the way to go.

If you're going to draw almost the same power, but the MH will also provide heat for your Canadian winter... then I think it's a no brainer. For veggies a single 400w MH is good for up to about 1sqm, 1.2sqm at an absolute stretch with the less light hungry plants, lettuce etc around the outside edge of the 1.2sqm.

Cheers, Yabbies.

[shaunmavronicolas]

Without starting another thread, I have another question related to MH... with tomatoes that have begun to set fruit, I have been told switching to HPS "Hybrid" bulbs encourages more fruiting and faster ripening, do you have any experience in this area Yabbies?

The hybrid bulbs contain about 30% more of the light spectrum covered by MH bulbs than the regular HPS bulbs.

When I bought bulbs, I got both types. We've been using the MH ones until now as the plants were still really pretty small. The tomato planrs are about 3 months old now, several plants have clusters of green fruit, should we switch bulbs?

Cheers, Shaun.

[MoeCanada]

Thanks Yabs,

I'll be buying a 400 watts metal halide for the 2nd growbed and this way i could do a comparison on growth between the two grow beds. One using T5HO and the other HID.
Will keep you posted of the progress with photos.

[shaunmavronicolas]

Moe, we have several of these... http://www.quantumhort.com/quantum-t5-badboy.html - - - 8 tube version. They consume about 500w, more I believe than a MH. We use them to grow all our seedlings and lettuce. I would be suprised to see these out perform the 400W MH, HOWEVER, what you will get is a much nicer even light, especially when placed pretty close to the plants. We have 2ftx4ft rafts under these lights and they work out perfectly.

We have one MH over a 4ftx2ft raft as well and the outer edges on the 4ft side definitly suffer from a light fall-off issue in our situation. That being said, we're using several of these over our main GBs, with a flattish reflector and the bulb hanging vertically and find it works pretty well. I think it really matters what you are trying to provide light to, so a square area, round area or rectangular area and how close you can get to the plants without harming them.

Hoping Yabbies chimes in on the HPS vs MH for fruiting

Cheers.

[Grownewb]

I've heard these HO bulbs have to be replaced as often as every 6 months. MH last for 2 years.

[Yabbies4me]

Sorry Shaun, I missed your post.

If you are interested in using MH during growth and HPS during flowering/fruiting, then I'd suggest buying a 400w HPS ballast rather than the 400w MH. You can get coversion globes for either ie: MH-HPS or HPS-MH, but you can't run a standard MH globe off a HPS ballast or vice versa (some may actually ignite and run, but you shouldn't).

The reason for the HPS ballast over an MH one is:

Most popular brands (Lucagrow, Son-T etc) of 400w HPS globes are actually what they call "dual spectrum"... just roughly, the Lucagrow provides 80/20% red/blue light, the Son-T 70/30% red/blue. Both are brilliant for flowering but still okay for growth (maybe a little stretch). However, if you run a MH ballast with a HPS conversion globe you won't get the same spectrum, and nowhere near the same lumen output.

As standard (again roughly from memory) a GE Lucagrow HPS globe run off a standard HPS ballast will pump out about 56,000 lumens, whereas a standard GE MH globe run off a MH ballast only pumps out about 40,000 - 44,000 lumens. When you run a HPS conversion lamp off a MH ballast you'll get even less lumens than the 40,000... as opposed to the 56,000 from the HPS ballast/globe combo. IMO the extra lumens are more desirable during flowering/fruiting.


Clear as Mud!...
.

[Herb Johnson]

After reading a bit on the t5ho's I would be very surprised if they could come close to what any 400watt grow light can produce. I have used 400watt MH globes in my grow rooms and they work well. I changed to 400watt HPS globes as they have a full spectrum range so there is no need to change globes over when flowering and I prefer to use the HPS globes as they burn cooler than the MH but I guess more heat is something you would welcome.
There are other environmental reasons why i stopped using MH globes http://www.darkskysociety.org/handou...-mh_vs_hps.pdf I have my 400watt HPS about 20cm above the plants and I use a Adjust-A-Wing reflector.

A MH globe will need to sit about double the height away from the plants approx 40-60cm form the top of the plants.
When you introduce your new MH light to your plants, keep it up high 90cm for the first day then bring it down 10cm each day until its down around 60cm away from the plant. now it is up to you to judge if the light could come down any further, this will depend on what you are growing.
I have had some plants almost touching my globes with very little signs of burn or stress.

I have found if the leaves are soft keep it high, if they're thick drop it down! (E.g. lettuce-soft leaves/Tomatoes-thick leaf).


I look forward to seeing the results