Saw this post last night, and thought about it for a while.

At first glance, you seem to have some tricky requirements - if the lights are at the front, they will blind you and then point to the ceiling when the canopy is opened. Additionally, this makes it tough to see into the tank while you are working on it. I have a possible idea for you. Knowing you are handy, and have plenty of experience building stuff, here is what I propose.

I'd make the hinge on the top of the canopy, just shy of half way back. The front part of the top and the actually front face would be connected and that whole 90* piece would fold back, giving plenty of room for you to access the tank. This is pretty standard, I think. I'd separate the lights from the canopy, by adding a 'shelf' inside the canopy for the LED's to attach to. The shelf should only be as wide as you need for the LED and would slide forward and backwards as needed. Could be as simple as a front to back piece of 1x2 on each side, or you could use commercial drawer hardware to accomplish this.

I think this would solve your major challenges with design- no matter how tall you make the canopy, when it folds up, you have access to the tank rim. The lights can just slide backwards, and you can do what you need to do in the tank without being blinded, and being able to see into the tank well.

Let me know if this is not clear enough.

 

Thanks for the help. I have the canopy framed out and boxed in, except for the front which I'll finish tomorrow.

That's a good point, I did think how I was going to lift the hood back without effecting the lights, but haven't come up with a plan yet. I made the hood on top split at 10" from the rear, measuring off the 3/4" back panel, which is pretty much the half point just about.

I bought 2 SS Piano Hinges to split the hood in half , so I can fold up only half or both

I'll add a pic of trim to overlap the cut when it's closed, so light doesn't show through

It took about 4 hours so far, making all the Kreg Pocket Holes and gluing took the longest.

I'll probably add a support in the middle, and use that to support the lights independently , so when I lift the canopy, the lights will still be sitting on the supports.

Like you said, this could be a simple 2x2" in the center, and 1x2" on the sides, to slide the lights back and forth.

I bought 2 x 36" lights, so with a 72" tank, this maybe an issue. It would have been easier with 2 x 24" lights, or one single 48"- 60" light

I'm not sure how the 2 x 36" lights will fit

I'll post some results and pics tomorrow, I'm hoping to paint tomorrow and trim it out Monday night

 

Another thing I did differently then allot of the online pictures I see, I added a pic across the front also at the bottom, to tie the entire canopy together structully. I also used 2x2" instead of 1"x2" for the frame.

Lastly, on the sides, I didn't want them to fold back, theirs no need to. I can make the canopy stronger by making a box all the way around. The sides are secured also to the frame.

The only part that will fold back is the front panel, and top half front that's connected to the front panel.

 

It's on the tank, 3 coats of white marine paint inside
Came out a little rough, I didn't sand it, or spray it this time since the holidays are right here, but it came out " ok "
I put a double piano hinge, so the front panel folds back, then the middle panel folds back
I also put a pc of 1x4" to hold the lights
I'll post pics this weekend when I finish it up

 

Canopy is just about done, I have to add some small trim in the middle of each door yet. It's 12" high, and splits in half to open. I also used a double SS piano hinge on each side, so just the front panel opens, or both the front panel and half the top opens