Oops! My apologies! As a "tank" guy, it never occurred to me that the sides were not to be attached to a solid bottom; I misunderstood the whole thing here. It's not a box at all...more of a fish corral...
I'll show myself out.
2000 gallon indoor Build
- Thread starter Dead-pool
- Start date
I'll show myself out.
If the bottom is ply wooded and everything is fastened and glued well. I wouldn't hesitate to go to 36-40". But keep in mind everything needs to be secured properly. Your dealing with a fluid. If even one section of 2x4 isn't fastened it will want to push the liner and 2x4 out. Especially near the bottom half of the pond.
Didn't know there would be strapping across the bottom. That completely changes things up. I used a sag calculator to determine how much an unsupported solid piece of white pine 16'X36"x3.5" would deflect under a uniform load of roughly half the weight of water that would be in the tank. Under static conditions for a short period of time the bottom of the wall would feel less weight. But that's not how the real world works. Over time the strain the material is under affects it more and more and that's not taking into account live load.
Not sure if it's OK to post but I've used this calculator on job quotes and I trust it. But I'd do alot more math before punching numbers in if my name was going on something.
Again i wasn't and dont think others were aware of any bottom cross braces from the initial post and pictures.
Will b plenty strong IMO even at 36”… This method has been tested and used many times over by now. I would not have done the metal strapping but it can’t hurt. I think the main part u missed is to glue the boards together tho. Something like liquid nails is usually always used in addition to screws. Typical “wall construction” holds just fine for ponds so this style is surely stronger than that. 1 or 2 top braces will prevent any bowing. Even if it does bow, ur using pond liner so theres not much worry. The pressure will be at the top of ur form, not the bottom also. If ur overly worried… run flat 2x4’s over the metal strapping and attach them to the sides. Fill the gaps between the wood in with insulation foam. I put up a 11’x7.5’x3’ with “wall construction” and no bottom at all. No bottom suports either, just 2 top braces. Ran and held just fine. Ur already way overbuilt than most people do for “ponds”… finish er out and let it rip lol…
Thanks Wednesday you are the authority on this from experience. I appreciate the advice. I’ll probably take this to 30-36” then.
i’m using screws pretty generously (almost 10lbs in of 3” deck screws 11 layers in. Will it be okay if i start adding the liquid nails now?
this is a huge relief. Thank you to everyone for all the advice. That what makes this forum so incredible!
Some valid and logical theoretical thoughts above but in practice I'd agree with Wednesday.
IDK if I would do the glue, probably not, and just screw a couple of vertical 2x4's on the outside or maybe even inside, but this is because I am stubborn and an experimenter. The path of least resistance is probably to do what's been proven and that's Wed's way.
IDK if I would do the glue, probably not, and just screw a couple of vertical 2x4's on the outside or maybe even inside, but this is because I am stubborn and an experimenter. The path of least resistance is probably to do what's been proven and that's Wed's way.
Many came before me… im just an old fish bum now
… not sure how much the liquid nails really does honestly. 1 guy prob just did it yrs ago and everyone followed. A 4” thick wall of 2x4 with 10lbs of screws in it aint goin no where tho. People used to just use 4”x4” stacked this way, drill a hole through the ends and use 1 piece of rebar/long bolt to hold it all together. No screws or glue at all lol. Being pond liner, u can always fill it up, see what happens and go from there. As others have suggested u might need a vertical 2x4 brace on the outside maybe at ur 8’ mark in the span to match up with ur center braces. I doubt it tho. Skinning it in ply wood could look better but thats just cosmetic. Adding 1/2”-3/4” ply to and already 4” thick wall of wood is a bit much IMO. The top braces will tie it all together in regards to water pressure. Id let it ride as u plan, fill it up, see what happens. No way its going to fail. Sure it might bow a bit in the center, nothin u cant add to tho if needed. Again, i dont think its going to anyway. Only other tip i can add is to use a cheap caulk on the seams after u put the foam layer in. It will help cut the 90’s for the liner so it doesn’t stretch too much in the corners. Its hard to tuck it in flush everywhere esp if ur by urself. I always do an overly stupid 1-2” of caulk
… prob dont need that much tho lol… might be able to find triangle shaped foam or something similiar for the same purpose.
