Overflow box for plywood tank

[Homer Siped]

So this is a 500 gallon that im in process of building. Before adding glass i want to get the inside plumbing finished so when i add water, i can test the entire setup with the drains and everything. I want to do a long coast to coast on the back, probably use 3" pvc and mount it from the top with plastic hangers so im not drilling screws into the tank. Use a saw and cut my weirs in it on a slight angle about 1/4 inch apart and about 1.5 inches deep. I can use the height of that to control the water depth if the power goes out. Might take a little bit of trial and error to get it right. Instead of running the drains through the side of my tank i was thinking about mounting a 10 gallon aquarium on the side, make a shelf for it to sit on and run the c2c right out the side and 90 over to the 10 gallon tank. Basically making an external overflow box out of it and have my drains set up going down from there. Have that set to come in lower in the 10 gallon tank to keep noise down with bean animal style drains. Also i was looking at the jabao mwd 20000 return pump. Ran a dct 15000 for 5 years with no issues. What size return off of that? Im shooting for between 4k and 5k gph as i have a snapping turtle thats going in here and they're pretty messy. Kind of want the return to shoot across the bottom of the tank to keep everything cycling around instead of just moving a lot of surface water. Any thoughts or opinions?

 

[jjohnwm]

That's going to be a beautiful tank when it's finished! Congrats, nicely done!

As I'm sure you are aware, your turtle is going to be a destructive dynamo who can manage to wreck just about anything. I'd be very leery of a coast to coast overflow, or really anything else in the tank with him. Your idea of an external small tank for the overflow is one I use a lot and it works very well. I would just install a bulkhead in your tank, and attach a short piece of pipe with a 90-elbow to the outside of it to dump into the small tank. If you fit a threaded union between the bulkhead and the 90 (outside the tank), you can loosen the union and then rotate the 90 up or down, which allows very fine control over the water level in the tank; the water level will be set by the level of the opening on the 90.

As an aside, you can also install a bulkhead inside the tank near the bottom, and then run an external pipe up from the outside of the bulkhead to the small tank. This works the same way as the other idea, but draws water from the bottom instead of the top. If you do this, you must install some sort of rounded or three-dimensional grate over the water intake in the tank to keep the turtle from getting itself caught on the intake by suction. I once lost a large softshell turtle that way, not a mistake I will ever make again.

 

[HUKIT]

I’m following a lot of these builds and damn some of you are very talented. I see a lot of home build tanks don’t have this type of cabinetry work so this going to be gorgeous!

 

[M1A1]

10 gallon aquariums have the thinnest possible glass you can imagine so drilling one tank for multiple bulkheads may be difficult without it cracking. Or maybe I'm an absolute ape with the glass drill but the only tanks I've ever had crack are 10's.

If you're feeling adventurous and want to skip more epoxy/fiberglass work, take a look at PVC trim board or PVC foam board which is now available at Lowes, Home Depot, etc., under the Royal Building Products brand. Full size (4x8ft) sheets of 1/4, 3/8, or 1/2 inch thick for $80 to $100. Glue it together with normal PVC glue and silicone the inner seams just like a glass tank. The 1/4" stuff needs a plywood backer as it's a bit too wobbly for my liking but 3/8 and 1/2 may be okay in standard 10-gallon-tank dimensions. I'm looking at this stuff for a potential mini-monster tank build along with the PVC trim pieces in normal lumber dimensions (1x4, 2x2, etc.) in order to avoid any epoxy/fiberglass work.