# Metal Halides and Paphs?



## Forever-mango (Jun 4, 2010)

I currently have an aquarium using a Metal Halide hybrid system (150w MH HQI + 2 24w T5 - All running planting bulbs). At the moment i have it suspended 40cm above water surface. I was wondering, how high should the lighting be so it doesnt burn the Paphs. And what height is best for them?

Kind regards
Stephen


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## goldenrose (Jun 6, 2010)

I'm not sure there's an exact answer to that. I would think a foot as a starting point? What type of paphs? Multis or barbatum types? Big difference in light requirements.


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## Forever-mango (Jun 6, 2010)

Hmm...its a mixture of Paphs...


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## Ernie (Jun 6, 2010)

Hmmm. 40 cm =~16 inches. If you had the same setup above those plants, I'd say raise them maybe 1.5-2 times higher than for your aq. Light is attenuated rapidly in water, plus the extra distance will give you more coverage. If it's not enough, lower the fixtures.


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## Forever-mango (Jul 31, 2010)

If the lighting is mainly for the Paphs and Phrags, what would you recommend? The aquarium is only to provide humidity for the Paphs. I get morning sunlight around 5am-noon. So how long should i run my lighting for and on average how would i know how high to suspend the light?

Kind regards
Stephen


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## Justin (Jul 31, 2010)

The PAR lumens from a 150 watt lamp will decay at too far a distance. Try about 2 feet from the tops of the plants. In a few weeks you'll be able to tell from the plants if it is too much or too little.

As for photoperiod, since you have morning light, suggest 12PM to 9PM in the summer.


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## TyroneGenade (Aug 2, 2010)

MH lamps get very hot (as you have by now noticed). The T5s do not get as how but still do get hot.

Light diffuses according to an inverse square law, so small changes in distance form target to source will greatly affect the density of the light striking the plants. Because of this a T5 setup with good reflectors would serve you better than MHs. For one thing, you can bring them closer. If the reflector wings are adjustable then you can narrow the focus of the light so little is wasted.

My tiny Tolumnia collection lives on top of my fishtank where there are less than 15 cm away from the T8 tubes and do OK, but they like it hot... Some Phals were quickly roasted.

tt4n


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## GaryB (Aug 2, 2010)

TyroneGenade said:


> Light diffuses according to an inverse square law, so small changes in distance form target to source will greatly affect the density of the light striking the plants.
> tt4n



Please note that this law only applies to a single point source. Tubes are not points sources and you have multiple source, so the intensity won't fall as fast. 

I'd go with Justin's advice; try it at 2 feet, see how your plants respond and adjust.

Gary


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