Ok, i'll try to answer everything in one post. First, plywood, i wouldnt say it's Forever... Glass tanks arent all forever, but i dont think that plywood will last as long, but for 1/3rd the price... i dont care. My Last plywood build was an experimental tank. Yes i had leaking, Yes i ran into issues unexpectedly, yes, yes, yes. BUT Now that i know what I'm preparing for, i have a WAY better chance at this thing lasting 10+ years. My new tank is so beefy compared to my project tank, that i dont think that i will ever have an issue as long as i did the water proofing properly.
A lot of people that i know of have done plywood tanks that are in-wall builds. Saves you a ton of cash not buying glass/acrylic thick enough to hold 300+ gallons. THIS IS ONLY COST EFFECTIVE that i am aware of for LARGE tank builds.
Yes, i applies the epoxy and paint color of my choice before drilling through it all for the bulkheads. And since i am paranoid about coming home later in life with 300 gallons of water on the floor and several hundred lost in coral and fish, I siliconed around the bulkheads and put a nice thick layer of silicon throughout the entire inside and a flexible water barrier. Just in case the wood does give a little and causes the resin to crack.
Also for the LED's, i researched a lot on ReefCentral and various other sites, Cutter, CREE, and some other random ones.
If you have any questions, feel free to ask, it's pretty basic electrical stuff.
Rapid LED sells some good priced DIY kits, but still, searching for the parts yourself and even with shipping can save you money.
The MAIN thing people overlook is the power supply. EVERYONE seems to think that you need a constant current device, like a meanwell or buckpuck. BUT if you buy a good power supply, like i did from circuit specialists, which have great prices for what they sell, and a inline fuse, you have a very stable powering unit. It does very a little on the current by about 50mA which is small, but you shouldnt ramp the LEDs to max capacity anyways, so they are safe. IF they happen to go over 1A, then thats what the fuse is for. I tested mine out, as soon as it hit 1A, boom, fuse blew. So I am confident that this is no issue and saved me a ton of cash.
With meanwells and buckpucks, you can only run on average, 8 LEDs per driver. With my 48v PSU, i would recommend getting the 24v version as your possibilities of doing more are wide open..., i am running 28 so far and have 2 extra amps to run 28 more, all for about 55 bucks in parts and shipping. Whereas, to run 56 LEDs on a meanwell (on average $30 i last saw) that would cost $210 roughly, that might not be including shipping... The only thing that i want to do now with my system is build a PWM for it so that it uses even less energy (currently 107watts including the PSU draw). So I think that i can get that down to around 70-80 watts if i did that.
The only words of caution i have for plywood builds is that you better plan for durability. 1gal of water weighs 8lbs according to a google search i did. I mostly had problems with the back bottom corners. But i had no back bracing, so it was just 3/4" plywood that was holding the weight over an 8' span which caused the wood to bow a little, but enough to spring dripping leaks. At most it was 1drip per 30min-1hr. So, not a huge deal. I did end up replacing both sides of my current tank because of the wood issue till i realized what the problem was. The leaks are hard to find since you cant see through wood.
But feel free to ask anything.