My Grow Rack

I wanted this to be my first post.

A little info:

• Apparently they call the bulbs "lamps" in the biz. So when researching lights, I kept reading that and started calling them that.
• Lamp sizes are Tn, where n is how many 12ths of an inch in diameter they are.

I started by buying a 74" x 48" x 18" metal rack from Lowe's. I bought casters to go with it so I could wheel the rack around as needed. Turns out it was a good idea, because where it ended up is right by the heater. So I angle the rack out into the room away from the heater in the winter. I only have my rack half the height it can be. And I have three shelves installed.


And I bought a 6-lamp high bay fluorescent fixture. It's High Output, and takes 54W T5 lamps. I got it online, because I don't think you can get the HO fixtures at Lowe's, Home Depot, and the like. I use 5000K lamps. They seem to work.


If you're shopping for lights for your plants, make absolutely sure it says it has a 95% reflective backing.  It might say parabolic or faceted or something like that. It practically multiplies each bulb's light by 3. The fixtures with a flat back, even if it's white, don't give you near the same amount of light.  Something like this is a no-no. Even this is a no-no. This is a shot looking up at my fixture:

95% reflective backing

See how each light looks like three lights? Happier plants!

The problem with my light fixture is it's 48.125" long and 17.5" wide. It can't hang inside the four corner posts. So I had to get creative. It sits on top.  But the posts aren't even all the same height. Two are a half inch or so shorter.

I drilled a hole and put a screw through it.

There was too much wiggle room, even after one snug nut, so I added a bunch.

This post is shorter. But the black pieces that you put on the posts to hold an installed shelf in place raise it just the right height to make it even with the taller post. This screw is real loose, but I guess it doesn't need any nuts to keep the whole fixture in place.

I bought 2mil 50" x 25' mylar to surround my rack with to reflect light back in. Then I realized my lights got hot and I needed a fan blowing under them all the time, so I just put mylar along the two long sides. Later, I took it off one side to help with air flow, because I was getting some algae. But that might have been caused by my covering the plants for waaaay too long after germination. Heck, maybe I should put the mylar back up on that side, too.

Eventually, I wanted to add another shelf of lights to my rack, but I couldn't get another fixture like I already had, because of the dimensions. I also wasn't crazy about sticking with T5s because of how hot they get. I said ah what the heck, I'll go the el cheapo route and get Walmart T8 shop lights and some lamps also from Walmart. People on the forums said they work fine.

Walmart shop lights.  No mirror or parabolic backing.

I didn't like how dim they looked compared to the T5 fixture on top of the rack, and I regretted buying these. Then I got this idea to try to make a parabolic backing myself.

In this next picture, you can see my first rough attempt, and their output compared to the fixture above:

I tried hacking the left one using an empty package of AA batteries, some corrugated cardboard, mylar, and tape.  The right one is standard.

Another shot of the standard ones.  Where it's reflected most
is just reflected back at the lamp. Useless reflection.

Another comparison of my first draft and standard:

First draft.

Standard.

From a forum post I made on the topic:

I didn't just put mylar behind the bulbs. See, at one end, the end with the pull chain, there's a black box. Initially, I was going to have the mylar go up over this, to give a curved backing behind each bulb. I saw I had a pack of AA batteries I bought recently, so I took the batteries out and used the empty packaging for the other end, because it was about the same height and width. This didn't give it the support it needed in the middle, though, so I took some corrugated cardboard, three layers deep (about the height of the black box), cut to the width of the black box, taped them together, and taped it along the middle. This worked. But then I realized I shouldn't be enclosing that black box; it probably gives off heat or something. I cut out a hole in the mylar to expose the black box. So the black box was the reason I picked that size, but I didn't even use it as support. 



So behind the lights isn't just flat mylar, it's curved, like an "n" behind each bulb, connected by a "u" in between.

Then I just tried coating the still-standard light's back with mylar, to see if that'd help anything.

Unshaped mylar covering original backing.

Better than nothing.

I was looking at the one I put curves behind, and I thought "maybe if I pinched along the middle hump to give it more of a point, that would help. So I tried it. (If I did it over again, I would just fold the mylar along the dead middle of the piece, instead of pinching after it's on.) My pinching was blind for the second half, and I curved to one side. I still think the pinching helped.


Before pinching:

Before pinching the middle.

After pinching:

After pinching the middle.

Looked like more light was coming down.  That's good!

I redid the parabolic one to be neater, and took a picture to show what's goin' on behind it.

Behind the mylar.

All I did now was put the mylar on a hard surface and put a nice crease along it with my fingernail, making it as straight as I could, holding it straight with tape as best I could. I taped each "U" behind each bulb into place against the side, and I cut out around the black box again.

It ended up like this:

Showing the shape of the mylar.

In this picture, I'm putting no pressure on it with my hand. You can see how the area between the bulbs isn't curved right, because there isn't much reflecting downward:

With no pressure on the mylar, the curvature isn't right.

Now some pressure to adjust the curvature:

With a little pressure added, the mylar is curved real nice,
reflecting lots of light downward

So I added some tape to keep the mylar curved better:

Taped mylar to hold a better curve.

Each lamp looks a lot wider than it is (look at the bottom of the picture for actual diameter). Nice.

Taken under one of the lamps.

So I did that to both T8 fixtures. I probably didn't use an empty battery pack in the second one, which might even be better.

Dang good reflection, 8 months after being made.

I have a fan and the three fixtures on a timer, and another fan aimed toward the lower shelf that I have to turn on when I remember to. It's not as important because the T8s run a lot cooler; it's just for airflow to prevent algae and mold.

Big fan on warm shelf, small fan trying to blow down between the two T8 fixtures.
The rack is angled into the room because of the heater on the wall.

The side mylar is taped to that black piece on the corner post that holds the top fixture level. What's nice about that is I can just turn that plastic and it's all nice and loose so I can reach in to move pots, feed plants, see what's goin' on, etc. Then turn it the other way and it's taut again!

I had to replace the top Rubbermaid container recently, because when I pulled one side out to water the tray, the lip shattered and the whole side got plenty of strain marks. Those lights make plastic really brittle.

That's all. Now you know almost everything there is to know about my grow rack.