What size light for 36x18x36?
This is the most common question I get, and I usually encourage customers to call me anytime (425.471.1425), this post isn't meant to dissuade calls but helps to get things started here on the Web.
The "tall" panel (2 inches in height) is usually the best choice, as you may be wanting the large LED diodes in addition to the LED strips to get more light down to the substrate. Large diodes aren't mandatory but are often recommended for the common plants most folks choose.
The first thing to consider is what top are you going to use? The stock screen top, your own custom replacement, or one of the many 3D printed replacements available from fellow hobbyists. This will help to sort out if your new light panel will be 34, 35 or 36 inches wide.
The Stock Top -- usually a 35" wide panel will rest securely here.
Custom Top -- if you completely remove the stock top and replace it with glass inserts, then 34" wide will usually be a secure choice. If you built your display from scratch, maybe 36" is the best choice? (for the look of an edge-to-edge hood)
3D Printed Replacement -- if its a Frogs N Frags top, then the 35x15 panel in my store was specially designed for that exact top. That panel also works well for many other replacement lids.
Keep in mind, all light panels have an open back for airflow and only rest on 3 sides of your vivarium (front, left and right edges), so grab your tape measure to be sure exactly how those 3 sides will rest on top of your display.
Large diode LEDs or not?
For low light plants, these aren't needed. However, if you do get one or two, they're easy to unplug and remove if its too much light, or if they malfunction you can easily swap new ones in. They come in 20, 30, and 50w power levels. 50w diodes are only really needed for displays over 40 inches tall.
Fans come already installed in the large diode heatsinks, but you can add additional fans to increase air circulation and exchange over the top of vents.
For these large panels I strongly recommend using a controller/driver combo. The NL502 digital controller is easy to use (plug and play) and easy to customize. If you're unsure how to make edits, call me, I can talk you through it.
The NL502 comes with 5 output channels, each one capable of different programming. For my own large displays (that have one large LED diode in addition to strips) I run the LED strips and large diodes on separate channels. I run a 14 hr cycle on the strips (sunrise at 6am, sunset at 8pm), while the large diodes only run at midday (at 100% output) for anywhere from 2 to 4 hours. This mimics natural light cycle intensity levels quite well and gives the plants that need more lumens at midday what they want, in addition to giving the animals the lower light levels in the AM and PM that they often prefer for foraging.