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Lettuce raft foam


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Old 03-21-2016, 10:39 PM
sander sander is offline
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Question Lettuce raft foam

I'm using a sheet of insulation for my lettuce raft, but I'm curious if its bad to have the reflective side facing up. Is it bad to have the light reflecting and hitting the bottom of the leaves?

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Old 03-22-2016, 05:45 AM
GpsFrontier GpsFrontier is offline
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Hello sander,
Do you have a picture or link to the type of insulation foam your using? The foam insulation should be the same on both sides. There's only one that I can think of that isn't, and I wouldn't use that type because it's an open cell foam so it absorbs water.

As for light bouncing back up from the foam, that's desirable. Defused light (light bouncing around from different angles) helps give more even coverage. You just don't want high temperatures, and/or extreme light intensity. Like sitting in direct sunlight all day getting hot. Especially for lettuce plants that typically are low light requirement plants and prefer part shade. Covering with shade cloth can lower the light intensity and heat buildup if needed.
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Old 03-27-2016, 06:36 PM
sander sander is offline
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Originally Posted by GpsFrontier View Post
Hello sander,
Do you have a picture or link to the type of insulation foam your using? The foam insulation should be the same on both sides. There's only one that I can think of that isn't, and I wouldn't use that type because it's an open cell foam so it absorbs water.

As for light bouncing back up from the foam, that's desirable. Defused light (light bouncing around from different angles) helps give more even coverage. You just don't want high temperatures, and/or extreme light intensity. Like sitting in direct sunlight all day getting hot. Especially for lettuce plants that typically are low light requirement plants and prefer part shade. Covering with shade cloth can lower the light intensity and heat buildup if needed.

My foam is white on one side and silver on the other. My other question is how high can I have the t5 lights? I'm using 2 48" tubes and my 3 rows are a total of 9" wide. I'd like to be able get another raft under the light
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Old 03-27-2016, 08:34 PM
GpsFrontier GpsFrontier is offline
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Hello sander,
That sounds like the foam board I was talking about that I wouldn't use. I don't know what exactly what it's called, but I think they use it mostly in the HVAC industry. It's aluminum foil on one side, and some other material on the other side, and the foam itself is a yellow/orange color. Looks a lot like this Foam insulation. the foam is an open cell product, which means each tiny air bubble has an opening that will allow it will absorb water like a sponge. You want to use a closed cell foam. If Your not sure, I would take a piece and submerge it in a bucket of water for at least 24 hours and see if it absorbed any water.

As for the T5's you want them as close to the plants as you can get them withough't burning the plants. Lettuce plants are typically a low light requirement plant, and that's why they work well for lettuce, but the lumin drop off with florescent lights is still significant. So you still want to keep the T5's as close as you can. Hopefully around 6 inches if possible, but I wouldn't want them much more than 12-14 inches away from the plants. Beyond 2 feet the plants will only get about 25% (75% drop off) of the lumins or less depending on distance. If your using multiple twin bulb light fixtures, I would space them no more than two feet apart.

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