1300 Gallon Plywood Tank Build

We are building a new house with a 1300 gallon fish tank off the great room. I would have preferred to wait until the house is finished, but our general contractor talked us into having the framers build the frame for our plywood tank. The design is based off VLDesign's 1500 gallon tank build
http://www.monsterfishkeepers.com/fo...d.php?t=209523
and
Gator's 600 gallon tank build
http://www.monsterfishkeepers.com/forums/showthread.php?181445-600-Gallon-Plywood-and-glass

It will be 1300+ gallons with two front 5' x 3.5' windows and one 3.5' x 3.5' side window. Filtration likely to be a combination of undergravel and canister, heating and lighting still undecided. I need to evaluate Pond Armour, Sweetwater, and bluemax. Leaning toward glass over acryllic.

The tank room was built on compacted base with 5" concrete with rebar on 2' centers. The inside dimensions of the tank are 137" wide x 48" deep and 48" tall. The framing utilizes a 2 x 6 pressure treated plate around the perimeter and down the middle of the tank from side to side. 10" tall 2x6 supports on 10" centers, with two more 2x6 plates and 2x8 joists on 10" centers. Walls are 2x6 on 10" center with 3/4" smooth plywood inside. Everything is nailed so far. I was concerned about nail pops, but the framer assured me that these nails do not come out. I have some concerns about framing the front of the tank to the side walls. The front wall of the tank is built between two support posts that hold up a house beam. I am comfortable with the structural capacity, but am worried about the corners flexing and cracking the liner, so somehow the front of the tank needs to tie into the sides better. I will be evaluating that this weekend. Here are some photos so far, including Gator's sketch of the design concept I am following. The Tank location is in blue on the house plan. I also had the house design include three skylights over the tank. Not sure if this is an algae problem waiting to happen, but hopefully with proper management of nutrient loads that won't be an issue.

View attachment 711265View attachment 711266View attachment 711268View attachment 711272View attachment 711271View attachment 711270View attachment 711273View attachment 711267View attachment 711269

I think the site was experiencing difficulties when I made the original post. It failed multiple times before successfully posting and the images were lost. These are from the original post. We have made progress since these photos and I will upload additional photos and have more of an update soon. The plywood is attached with ring-shank nails that I am told will lose their head before they pop, but I might screw on a second layer of 3/4 inch ply just to be safe. Seems like overkill, so I am still undecided.

As for under gravel, I really mean a reverse under gravel with multiple zones. Specifically for the purpose of keeping debris and waste from settling, also my secondary goal is to maintain a high degree of water movement to reduce algae growth. This would be a separate pump from the canister (or pool sand) style filter and I would rotate the flow through the various undergravel zones on a schedule. I am not really sure that is necessary, but would give me higher flow in each zone with a smaller pump.



I missed a couple photos in here, but there are 2x8 joists on 10 inch centers running from the front of the tank to the back across the three 2x6 stem walls. The front corners are toe nailed into the osb covered posts holding up the beam above the tank.