Thanks! Through this build I have learned the box structure using pocket screws is really strong and can support more weight than our tanks can produce. I wanted to use glue as well to strengthen more but just forgot. I could have removed the screws, put glue and screwed again but I figured why weaken the wood. It got reinforced with the molding trim as well.
The reason why I went with the box structure vs the 2x4 frame with skin is it maximizes the inside space a lot. This was the only way I could squeeze in an Emerald 34 sump. I wanted as large sump as I could fit.