Need input on my DIY canopy design...

[tang_man_montreal]

I'm going to be putting in 2 x 250w MH's very soon. Because of this, my current canopy will no longer do. It only has an outer height of 8".


- The new canopy will be 16" in height.
- I'm using 1/2" Pine, Outside will be stained black
- inside will be weatherproofed, and then coated with reflective Mylar (using spray-on glue)
- The back will be half-open.
- 4" Fans on each end of the canopy.
- Front 5" of Canopy will swing open onto itself (for major access), using a piano hinge
- Front will also have 2 cupboard style doors for quick access for feeding/etc... (not yet on design)

I designed a schematic this morning, and now I need input on anything I may have forgotten.


My Design

Thanks everyone!

[texasreefer]

On your top I would design it to lift the front and top at the same time. That way you can have access to your tank easily for moving large rocks or lighting. Then also keep the front doors like you are planning for feeding. The last one I built was like that and it works out great. I would also use 3/4" plywood to build the canopy. By using plywood it will be less likely to warp than solid wood will.

[celticht32]

I would stay away from using mylar in a hood... one is heat problems the other is fire problems...
use either white paint or you can get silver as well... but I would stay clear away from the mylar...

chris

[tang_man_montreal]

I've heard people debate over the use of mylar and heat issues.

The fact remains, that many people have used mylar successfully, including the person that I'm getting the MH's from, who is a member of this board. Maybe he'll reply with his remarks.

As long as there is sufficient space between the lights and the mylar, there is no problem.

[tang_man_montreal]

BUMP

[pmui]

-no mylar
-seal the wood with SPAR polyurthane
- paint flat white
- use outdoor weather strips to block out the lights, where the light peeks through.

What size tank will this be on? Pine then to warp in longer lengths, I would use 1/2" - 5/8" plywood.

Peter

[tang_man_montreal]

Everyone keeps saying no mylar.
Has anyone had bad experiences with mylar?

As the design shows in my first message on this thread, it will be going on a 90 gallon tank.

As I mentioned, I know someone currently using mylar with 2 400w Radiums, and 2 actinic VHO's. IN A COMPLETELY ENCLOSED CANOPY. The 250w saki's that I'm getting were in this canopy before as well.

I'll get him to tag onto this thread so he can post his remarks as well.

I could probably understand if the mylar was too close. But I'm looking at ATLEAST 4" between the MH bulb and the mylar.

As for ventilation, I've decided to have 2 4" fans blowing over the water surface, and 2 4" fans pulling heat out of the top of the canopy.

Wood: I've decided to go with 1/2" Oak Plywood instead of Pine and seal it with SPAR polyurthane.

Good idea for the weatherstripping! Thanks for that tip!

[pmui]

Tang,

The reason I would not use mylar, is if moister, water(salt) spray gets on the surface it will cause it to deteriorate and cause it to flake. The relective property of mylar is surface sprayed on so it will flake off over time.
Please post pictures when you have it built.

Peter

[tang_man_montreal]

pmui..

Hmnm.. Never thought of water moisture affecting mylar. I wasn't aware of that. I'll look into it...

Although, as I mentioned, My friend's been using mylar in his canopy for the longest time. No heat or flaking issues have been reported from him.

Maybe once he gets on this thread, he can interject with his thoughts.


I promise to post pictures of the progress AND finished canopy!

[Toutouche]

While I don't wanna start saying who's right and who's wrong, I'm gonna say that I've been using the mylar ever since I had my canopy made. It is a totally enclosed design, and I have never had any problems with moisture on it. I even had an overflow happen once when I was out quite awhile ago, and ( don't ask me how THIS happened as I still don't know), when I got back I found all the mylar completely wet and dripping ( needless to say, along with the floor). I wiped it all off with towels and I still have the same one in place with absolutely no damage to it what so ever.
I was running it with 2 x 250w. 6500k Saki's, and VHO actinics. Now there is 2 x 400w Radiums in there, and still no problem. I checked when I installed the new lights for heat buildup, and it was fine. The canopy is originally all white inside, and I got a much better result after installing the mylar. It turned the canopy into one big floodlight.
Have any of you actually used mylar, with what setup, and for how long?? Did you actually have the problems you've mentioned??

[tang_man_montreal]

UP!

[Toutouche]

What??? I looked up and there was nothing???
Just sent you a PM, and now I remembered something else to PM ya!
Hmm?? Seems like no one with actual experience as far as the mylar is concerned can answer back???

[Technobuyer]

Originally posted by tang_man_montreal

Wood: I've decided to go with 1/2" Oak Plywood instead of Pine and seal it with SPAR polyurthane.

That's almost exactly what I did... Mine's 1/2" oak ply built on a poplar frame. 2 coats of Minwax stain, and if I remember right 3 coats of minwax marine spar varnish.

Here's a pic:

[pmui]

I made a canopy for a rainforest type terrarium setup. The high moisture made the mylar deteriorate. The canopy had several NO lights mounted to it, but the humidity in the tank was close to 100% at all times. The plants thrived and out grew the tank. From that time on, have not used mylar under canopys. That is just my experience with it.

Peter

[johnny]

I've had a mylar lined hood on my 150g for almost three years without a problem...

Nick

[tang_man_montreal]

johnny, what are the dimensions of your hood?

Are you using MH's?

How far away are they from the mylar?

what about water damage to the mylar? Is your hood completely lined with mylar? (top and sides)

[johnny]

The hood is approximately 74x20x15. Both top, sides and front are lined with mylar. The MHs are 250W iwasakis and are about 2-3" away. There has been a lot of water splash on them, no noticeable problem though, the only problem is the tacks I used to put it on with have rusted.

I'm wondering if maybe the glue you used to put the mylar down with ate through it?

Nick

[tang_man_montreal]

Hmm..

Johnny, You have no heat issues with the MH's being so close to the mylar? What about fans? How many do you have pushing are through there? Or are they pulling hot air out through the top?

As for the glue deteriorating the mylar.... never thought of that. I've used this spray on glue for many things before, but I will try it on a scrap piece of mylar and wood to see though. I definately won't use tacks or staples though, because of the rust issue.

THanks!

[johnny]

nope no heat issues. No fans either. It was an open back hood until this year, now I have it closed and one vent (soon to be two hopefully).

Nick

[Toutouche]

Like I said, I too have never had any problems. Even when it got all wet with saltwater once. It is still ompletely intact! I'm curious as to what would cause it to peel or flack for the others. Especially if this stuff is, afterall, made for humid and hot environments such as plant growing???
Maybe one of us should actually ask at the hydroponic stores about this possibly happening, and what they have seen as problems, or happening?

[getoutofmyway]

what is wrong with using a metal ...... aluminum reflector you will get more reflection this way??

[Zigzag Man]

I used adhesive foil tape inside my hood like they use for connecting ductwork. You can get a large roll for around $13 at HD, plus you can easily conform it to uneven edges. It would probably be easier than trying to stick mylar with spray glue, but that's just my .02¢
Personally, I'd be leery of having a plastic-based reflector hanging 4" above a light that will reach high temperatures. If the adhesive happens to break down, the mylar will drop down and possibly touch the bulb... and that could be a bad thing.
Of course this is all just my opinion, and like reef tanks, I find that there's quite a variety of them.

[Crawdad1]

What type of glue did you use that was able to stand up the intese heat of the 400wMH?

[johnny]

zigzag,

it would be almost impossible for it to hit the bulb as it would have to curl up and around the reflector to get to the bulb, but I understand what you're saying just the same

Nick

[Crawdad1]

Does any one have a picture of their mylar installed inside of their canopy?