DIY : Tiffany's Koi Pond

This was my solution for a quick 250 gallon pond which could be seasonally setup or stored away. My application was indoor, for my summer Koi-selling pond season. It took me about 12 hours to build the complete structure. I've had many customers asking for the plans, so I've put them up here on my web site.


Pond Photo

The heart of this project is a pre-formed pond insert. I chose the Laguna P-796 as it was the largest I had access to. This particular insert is a rectangular 'tub'. While one catalogue lists it as a smaller volume, my measurements tell me that it holds about 250 gallons. It is free standing and self-supporting, so everything added is just for appearance.


Pond Drawing

The wood facing (deck) is cedar. Decorative sides are cedar-coloured plastic trestle (UK) or lattice (US). Framing is 2x4 construction lumber.

For tear down, the facing is removed (wood screws) and the frame is unbolted (wing nuts) into 2 halves, which then fold up flat. These parts and the pump and filters which were used with it, are then put into the empty tub and put away for storage.

Other applications are to have this free-standing in a yard, or build a deck around the tub (permanent or seasonal installation), or to be used to over-winter Koi indoors.

I've listed a bill of materials at the end of the article, cross-referencing the figures the parts first appeared in. All dimensions are in inches. Drawings are 800 x 600. The original unit was made from sketches, and these drawings were made later, so please contact me if you find any mistakes or omissions.

Details...

Step 1: Start by building two side frames as shown in Figure 1 (I used 3" spiral nails).


Figure 1, Frame, side piece

Step 2: Then build two end frames (Figure 2). At this point, I stained all the visible lumber with a latex stain which matched the colour of the trestle used.


Figure 2, Frame, end piece

Step 3: Position an end frame against a side frame as shown in Figure 3, and clamp them together on a flat surface. Add 2 hinges as shown. Repeat with the remaining end and side frame. Opposing corners get hinges, and opposite opposing corners get bolted (this becomes more clear in the next illustration).


Figure 3, Frame, hinged section

Step 4: Slide the two frame halves together around the tub and clamp them together. They will be held together by four carriage bolts and wing nuts. The drill location is not critical. At this point I jigsawed the 4x8 sheets of trestle into 2x8 sheets, and marked where the openings in the trestle would allow clearance for the wing nuts. The carriage bolt must be far enough away from the nails holding the frames together (reference Figure 6).


Figure 4, Frame, sectional top view

As shown in Figure 4, I used a pressfit nut and a carriage bolt (5-1/2" long), flat washer, lock washer and wing nut. I can't recall the dimension of the hardware, but as 1/4 would be a bit flimsy and 3/8 overkill, I probably used 5/16". The hole for the carriage bolt goes through 4" of lumber, so I used a small pilot and a brace to keep my drill squared to the lumber (most drill bits are not long enough to drill 4", so it takes a bit of time to get both holes all lined up through both frames. With the pressnut and large flat washers on the other side, all holes can be somewhat oversized for easier alignment.

Step 5: In Figure 5, the tub should float inside the framing. I made the framing 1/2" higher than the tub, so I could put a bit of insulation under the tub. This insulation is optional depending on your application. Nothing needs to be used to fill the 1/2" gap as it is hidden under the facing.


Figure 5, Frame & Tub, top view

Step 6: Referring to Figures 6 and 7, start by installing a 2x8 sheet of trestle on the side which is most predominant. The trestle I used was the regular plastic 4'x8' sheets. There is a privacy version which has smaller holes and might look better in this application.


Figure 6, Trestle, side view

It is possible to line up 3 corners of the trestle to match perfectly, so locate the mismatched corner out of sight. After attaching the side piece, align and attach an end piece continuing around the structure and trimming the excess as you go.

I used brown 1-1/2" decking screws to attach the trestle (or lattice). Each hole was piloted and countersunk for the flathead screws used.

Step 7: Note the location of the fasteners on the end pieces (Figure 7). If you are using the design's capability to have the frame come apart and fold together, then do not fasten the trestle to the ends of the side frames.


Figure 7, Trestle, end view

Step 8: The cedar facing used and shown was 5/4" x6". I might use a 5/4" x 8" next time to more completely hide any gaps between the tub and the frame. When filled the tubs bows slightly, and the middle of the long sides bows inward, so a gap is more evident.


Figure 8, Cedar Facing, top view

I used brass corner caps for looks and to hide my poor mitre cuts. I used brass 90 degree brackets to hold the inside corners in alignment. If the facing will be seasonally removed, mark the underside for location to a frame corner for future alignment to the mounting screws.

If I was building this at a residential site, I'd probably include some type of a roof to the structure. Perhaps an archway using the leftover lattice, or a pitched roof & bucket to make it look like a wishing-well. The extra shade would help keep the water from getting too warm, and also help prevent algae blooms (green water).

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