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lighning questions for intermedia/highlanders


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#1 Satsvear

 
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Posted 16 October 2011 - 21:11 PM

I grove some helis and a Nep intermedia, because of the problem cooling them at night I was thinking of moving them to my parants basement. The temperature there is about 15c (57f). In daytime my lightening will hot up it and at night the temperature will drop. It would be perfect no expensive fridge and stuff.

The problem I´m thinking of is the lightening. In the beginning I think of using my fluorescent. I work pretty ok now, if the plants like it I will sooner by a cfl lighning. I now hps is better but I don´t want the heat and everything around.

The questening is, how far from the plants can I use my fluorescent? Will try have it so close as possible in the beginning. Can I use it 1meter from the plants? If/when I switch to clf what is the max distance from the plants? How big need the plants be before I go over to "red" flowering light?

Thanks for all tips!

Well Met!

#2 johns

 
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Posted 17 October 2011 - 09:43 AM

Having the plants 1m away from the light source is in my opinion unrealistic using fluorescent lights, unless you use a lot of them. Double distance = 1/4 light.

When it comes to fluorescent lighting I think the best idea is to use T8* tubes (in my opinion the light distribution is more even than with CFLs), and place them as close as possible to the plants. To reduce heat, place a clear glass or plastic plate between the lamps and the plants. Use one or more computer fans on top of the glass to cool the lamps. Choose the best distance for the plants according to the heat/light gradient.

Shop light fixtures are sometimes recommended, but as far as I know only electricians are allowed to install them. T8 fixtures and reflectors intended for aquariums don't have that problem, and can be pretty good for growing plants.

Whatever lighting source you choose, it's important to use reflectors.

Good luck.

* Recommending T8 here because T5/T5 HO would be less efficient because of the low temperature.

#3 Satsvear

 
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Posted 17 October 2011 - 18:12 PM

I have thinked about this today. In the beginning I will have the plants near the fluorescent light. When i building the place for the plants I do so you can chance the height. In the beginning I will have it close to the top. About 20cm (8tums) and when the plants begin to grow very much I can make the different between the botten and top for example 50cm (20tums). I later buy some more flourescents tubes.

I will begin with 2x24w t5 tubes. I think later to buy 2x39w and use both when the distans will be a little more...

Is this a bad ide or?

Well Met!

#4 johns

 
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Posted 17 October 2011 - 19:48 PM

In a almost closed terrarium (which is a converted aquarium), I get about 4-4.5 degrees Celsius above room temperature with plants about 20cm below 2x24W T5 HO tubes. I use a fan but there's a lid keeping the hot air in, and some of the hot air goes directly into the space where the plants are. I don't think you'll get as much heat at the same distance if you do something like what I suggested. I think my terrarium/aquarium traps a lot of heat.

You didn't mention how many pots you want to have under the lamps, i.e. how large the growing area will be, so I don't know if two tubes are enough.
It's worth remembering that the light is strongest directly below the tubes and drops off to the sides. With 2x24W T5 HO tubes I wouldn't calculate more than 50cm x 20-25cm growing area, depending on various factors (distance between the tubes, distance from tubes to plants, light demands of the plants). You'll probably be happier if you use one tube too many rather than one too few.

I find it useful to use a lux light meter to get an idea of how the light intensity varies e.g. in the middle and to the side of the growing area. One has to be careful with using lux as an absolute measure though, as the value depends on the light spectrum output by the tubes. Fluorescent tubes intended for plant growth give lower values than regular ones because they waste less energy on parts of the light spectrum not used for photosynthesis.