Neptune Aquatics

Plywood 120G sump, about $150

rygh

rygh

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Some of this is in my tank journal, but I decided to make a special thread.

I have always been a fan of plywood tanks. Almost built my main tank out
of plywood / glass. But chickened out. Just too big.
But sumps and refugiums are great to make out of plywood.
Especially since there is really no need for any viewing window.

The big advantages:
* Pretty cheap. (About the only thing cheaper is rubbermaid bins and such)
* Can be built to pretty much any shape.
* Very well insulated. (Wood itself, but also easy to add insulation)
* Use standard woodworking tools.
* Good strength/weight (If engineered that way)

Problems:
* You need to make sure they do not leak. Especially seams.
* Opaque. (Not always a problem)
* Take some woodworking skills.

Caveat : Do not attempt a big plywood tank if you do not have a decent set of power tools.
In particular, a table saw is pretty mandatory.


THE PLAN:
Box will be 40" long, 24" wide, and 40" tall. Water level about 4" below top at max.
It ends up being 115 Gallons. A good percentage of a 250 gallon tank.

Everything except epoxy was bought locally at Lowes. Even the thin acrylic. Cheaper than Tap.

Construction: Basically, the walls will be a laminate:
* 1/8" Acrylic
* 3/8" Plywood
* 1" Stringers(studs) / insulation foam (between studs)
* 1/4" Plywood.

The Acrylic will be glued to Plywood with epoxy. (Sand Acrylic first)
Ply/stringers are glued with waterproof wood glue, and screwed.
It all acts like a big I-beam, so while plywood is only 5/8" total, it should be equivalent to 1" or more.
There will be a small top beam across the top in the middle as well, since a 40" span is fairly large.

A big bead of thickened epoxy will be used where all the walls/floor meet.

Pictures to follow.
 
Here is a picture of the longer wall.
You can see the horizontal stringers.
Stringers are really just made out of scrap wood.
All ripped to 1" wide. Important that they are all the same depth.
The thicker ones are a ripped 2x4. The thinner ones are leftover 3/4" ply from the base.
It is good to have thicker ones at edges, for screwing into later.





From Aquarium_Release
 
Here is a picture of the longer wall, but this time with insulation added.
Simply glued in strips.





From Aquarium_Release

BTW: It was a fair bit of work ripping all those stringers (studs). But not that bad
with a table saw. In retrospect, probably should have set up a jig on the band saw.

For perspective, black square on left is 2 ft long.
Stringers are about 3.5" apart.
 
Quick status:
The 1/4" back is on the larger 2 walls. So they are a big solid structure now.
I epoxied the 1/8 acrylic on those 2 walls as well.
I need to assemble it before I can do the other walls.

A bit disappointed in my epoxy job. Quite a few spots with air gaps.
Not a structural issue. There is no strength needed there. But a bit ugly. Well, it is the inside of a sump...
I am clamping it overnight, but no way I can vacuum bad something that is almost 4' square, so will
have to live with it.

Pictures tomorrow hopefully when I un-clamp it all.
 
STATUS:
Well, a fair amount of progress as you can see above.
It is all put together, and partly water tight right now.

I still have one outer skin to put on, but needed to drill hole for pump drain pipe first.

I need to epoxy one more seam. I will probably sand them, and also coat with silicone.
A bit of extra work, but a good combo. Strength of epoxy + flexibility of silicone.
The walls/floor are epoxied together, so even the joint is waterproof.

I also need to finish painting the outside.

The top will probably wait until I have a better idea on what goes where.

So might be done this weekend.
 
Water test.
Very happy. The side deflection was less than 1/8". Better than expected.
Oh, and no leaks.
But moving it outside was a pain. A bit heavier than expected. Oh well, not like I need to carry it.





From Aquarium_Release
 
To-Do:
Needs a coat of real paint. Just primer so far.
I think I will let the kid choose the color. Goes in the garage, so just having fun with it.
Also needs some fiddly bits, like a power head mount and heater mount.

Oh, and of course, noticed that the floor where it is going is totally NOT level. Grrr.
 
hows this guy doing? still no leaks? I have a weird fascination with plywood tanks. I'd love to build one some day just to try it out.
 
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