Vivarium lighting with T5's

[Turtle81]

OK, I have spent the last week pouring over these forums and others tying to work out how many 8Watt (12inch) I will need for my new Exo Terra Natural Terrarium (45 x 45 x 45 cm / 18” x 18” x 18” (WxDxH)) and I think I’m more confused than when I started ! I would use 13W t5’s except they are too long and overhang the edges by about 3-4 inches.

I plan on growing my small cattleyas in it, I currently have:
Ctna Dal’s Capri x Bc Dal’s Charm
Pot Dal’s Emperor x C Jerome Shultz
Blc. Momilani Rainbow x Slc Red Jewel
Slc Jungle Treasure x Blc Waianae Leopard
Slc Pink Love x Slc Seagulls Mini – Catt Heaven

They will most probably be 9 inches at the furthest point away from the light fitting; I just wonder if I need 2, 3 or 4 8W T5's to provide the required amount of light as I know they need a fair amount of light and they won’t get much outside light either. I'm currently thinking 3 or 4 bulbs?

I just don’t want to spend the money to find out I should have bought a larger fitting! .... or a different type of light?

Any help/ideas would be most helpfull and ill try to keep you updated in its progress although it will be a slow process due to $$$

[Ray]

I am not familiar with 8W T5s, but I can tell you that 3 of the 24W bulbs about 12" above the plants was about right for cattleyas in my terrarium.

Doing a quick Google search showed that the 8-watters have roughly 400 lumens output (compared to about 2100 for the 2-foot, 24-watters), so if you're matching lumens (not entirely the correct thing, but close enough), you'd need 15 of them to match the three 24W bulbs.

[isurus79]

I think Ray is right on the money with this one. Using 8W bulbs is just not enough light to grow orchids with unless you have a lot! When you get t5 bulbs, you need to get the High Output or HO types.

[Turtle81]

Thanks for that feedback, looks like i will need to look more closely at the compacts then or put up with the lights being longer than the unit ... back to the drawing board i go !

[Turtle81]

An update so i am using 2x 24W t5 HO's for 13hrs a day and 2x 24W t5 HO's for 14hrs a day and the plants are about 10 inches away from the lights. I have noticed some purple starting to show on the new growths after 2weeks off having the lights.




Am i worrying about nothing or is the above purple colour a sign of too much light? should i cut down to 3 lights like ray said he used? The older leaves have not changed colour.

I just don't want to give them to little light as i hear that's more common lol

[Ray]

So if I understand correctly, you run 4 lights, and two run an hour more than the other two?

Why do that?

Yes, that's probably too much light.

[Turtle81]

Hi, I was doing that so that i could view the plants in the evening without providing bright lighting for to long, i suppose mimicking the dusk period of the day.

Thanks for the feed back ill try 3 lights for a while and see if that helps.

You have a nice websight ray i had never even thought about S/H for orchids ..... another excuse to get some more plants

[isurus79]

This is one of those rare times when I have to disagree with Ray. Red/purple coloration to me has always meant that your plant is getting an ideal amount of light. Plus it looks better than plain old green. I also run 4x24W t5HO's on my indoor Catts for 14 hours per day and they love it. I have been getting great results with my Catt. violacea, walkeriana, maxima and amethystoglossa; most of which are considered 'tricky' to grow.

[Ray]

At what distance, Steve?

When I had 3 Hydrofarm "High Performance" strips in my terrarium, I had to elevate them to about 14" above some encyclias to keep them from burning.

And there is nothing wrong with disagreement!

[isurus79]

Originally Posted by Ray

At what distance, Steve?

When I had 3 Hydrofarm "High Performance" strips in my terrarium, I had to elevate them to about 14" above some encyclias to keep them from burning.

And there is nothing wrong with disagreement!

Unfortunately, my plants are varying heights! The lowest statured plants have leaves at 10" away and my amethystoglossa is only a few inches away from the lights. It might actually be easier to see my setup, so here is a link to my flicker album for this tank: 10gal Orchidarium - a set on Flickr

Its a bit more densely planted now, but basically still the same. My newest walkeriana and violacea growths both had some brilliant purple coloration, but that tends to fade away as the growth matures and hardens.

As for disagreement, I think good disagreement can be pretty fun!! Especially when having a discussion with an experienced grower!!