Your build is fantastic! I have been searching for a great documented build, and with your thread, have been able to answer many, many questions I had.
I do have a few others. From my reading, 2 inches seems the smallest you can cut your plywood to support your viewing panel. What size did you go with? It looks bigger than 2 inches.
I really like the 45's you did in your corners. Do you think you would have had the same outcome if you would have put in wood 45's, glassed them, then epoxied over that? Same strength, while still looking flawless?
Once again, thank you for your documentation. I plan on building a couple 450-500 gallon later this year, and you have given me great insight!
Thanks, glad to hear it's been helpful.
Regarding your first question, the front panel of wood is about 4" wide around the perimeter. However after accounting for the edge epoxy chamfers/filets and the other plywood walls, this leaves ~2" of flat space around the perimeter of the opening on the inside. I have ordered my glass such that it overhangs the wood by 1-3/4" (so less than the 2" you mentioned). Based on the reading I did from other builds, it seemed to me that the general rule was anything over 1" was sufficient, and I am certain you reach a point of diminished returns very quickly.
I can tell you that I have very high confidence in the width of this overhang. Obviously it hasn't been tested yet as I'm still waiting for my glass to arrive, but I have no reason to worry. My biggest struggle (as I mentioned a few times in this thread) was deciding whether or not to also provide support
under the glass instead of just the front rim. Building a plywood aquarium is definitely a "choose your own adventure" kind of project... So, whatever you feel comfortable with.
Regarding the 45's, I know there are many successful builds that use wood in the edges (and then fiber / epoxy), such as one of the builds I linked in my first post. If properly fiber'd and epoxy'd, these tanks are virtually indestructible anyways, so yes I think it would be more than satisfactory. That being said,
pouring an edge is arguably even easier to do assuming you have the space and manpower to move the tank, and it is obviously super strong and water tight. My recommendation goes to pouring the edges.
I appreciate your comment about it looking flawless! haha. There are a few aesthetic details here and there that are not quite perfect, but I had to remind myself that it's all being covered with rock / sand / coralline / etc... so most of it didn't really matter at the end of the day. The most critical areas for making the epoxy "look" good in my case are the inside back, and the entire outside including the overflows. I wanted to feel proud of the tank when I'm working on it in the maintenance room so it was important to me to try and make those parts visually appealing too, even though they won't be seen from the display side.
I poured the outside back of the tank and just let the epoxy flow over the edges (where I brushed it off and later completed the sides). Since the epoxy thickens quickly, a 1/16" - 1/8" or so layer remains and forms a meniscus of sorts at each edge. I then popped the microbubbles with a hair dryer for the large sections and a lighter near the edges or for tough bubbles. That's how I achieved a smooth surface on the exterior back, top, and front. I found working with tape dams to be far too irritating and difficult so I scrapped that idea quickly.
Longest reply ever, but hope this helps. Thanks for your comment.