Long, shallow freshwater tank build

[keepingwater]

Hi all! First time poster, and a little out of place. This will be a freshwater build, but this forum is one of few remaining with a DIY mindset and active community, so I’m crashing your party. I hope that is ok :)

What I’m making is a 300x65x50cm (120x26x20 inches) open top ”natural aquarium”-style tank. There will be some small land areas and emersed growth, but the focus is on the water section. I will basically go out to a forest lake, gather leaves, twigs, moss and plants and see what it evolves into. I’m aspiring to something like an old-school natural museum diorama. We’ll see if I get there :)

There be a lot of plumbing involved with a sump, in-line live food culture section and drip water charge system. You guys are better at these things than any freshwater forum :)

So far I’ve built the stand. It’s increadibly overbuilt, but that’s partly because I may change to a taller tank at some point and also because 45x90 profiles were cheaper than 40x80 and almost as cheap as 40x40. And with ”cheap” I meant ”eye-watering expensive”.

I’ve build several large stands out of wood before, but I was curious about aluminium extrusions and I was tired of twisted and warped 2-by-4s that make alignment a pain. Another reason for going with extrusions is that this is in my basement and there is no way to get something this large down the stairs. This stand can easily be taken apart if we were to move.

Putting this together was fun and easy, but it requires some planning. I haven’t checked for square/twist yet and I’m a little worried that there isn’t much I can do if it isn’t perfect as-is. A wooden stand you can always plane, even if no fun. We’ll see!

Anyways, next step will be to make a top and skin the stand and then order the glass after summer.

 

[commod0re]

Nice stand! It looks great. This should be a fun build

Whenever I build printer frames out of aluminum extrusions I use an engineer square to check each corner in all three directions and rarely end up with much more than a tenth of a degree of skew so that’s what I would suggest doing. Check (and adjust into square, if necessary) either the top or the bottom first and then use that as your point of reference for the rest

 

[Ernie Mccracken]

Great stand. When does everything else arrive?

 

[keepingwater]

Great stand. When does everything else arrive?

I think it will be rather slow going. I want to have a continuous water change system (the advantage of freshwater :)) and that will require plumbing work in an adjacent room. I just tore down my old tank and not really in any hurry to get a new one up. I also enjoy the planning and build phases so I’ll take my time :)

 

[keepingwater]

I’ve had some progress on getting the stand panels in place. It was quite finicky since all the t-nuts have to be in perfect position and you have very little room adjusting them once the panel is in place. I little trick I learn halfway throught is to first use really long bolts since it allows for more wiggle room, then get everything in place and lastly replace the long bolts with the final ones.

Another issue I had is that I used roll-in nuts with a spring loaded ball for this, but they were still really hard to keep in place. They would ”turn over” if you as much as looked at them wrong. I think it’s because my profiles didn’t have a flat bottom of the slots and you’d have to perfectly balance the ball on a little ridge. I had to resort to a dab of cyanoacrylate to keep them in place.

Overall, this was a strong negative for aluminium profiles over wood. It’s nice that the panels are removable though, in particular since my sump won’t fit in without some juggling around.

Anyways, I’m writing since I have a plumbing question. Before I’ve always drilled the bottom and just used two standpipes. This time I will drill the sides instead since 1) I’m worried about the very long bottom cracking and 2) I want to be better able to capture and adjust leaky fittings. I’m not sure if I’ve mentioned this, but the tank will have a 3d-printed background with integrated weir. Is there still a purpose for enclosing the drains in a box, or can I just have them inside the background? I’m thinking a box will lead to a larger fraction of the drained water coming from the surface (via the weir), but I’m not sure if that is a pro or a con. Any thought?

 

[X-37B]

I have been thinking of doing this on a smaller system, 48×24×16.
I want a corner oveeflow thats 8" high so I can have pleny of space for plants, with various areas for above water creatures.
You can drill a box overflow, they make kits. On my reef systems I have this type of overflow.

 

[keepingwater]

Thanks, but I was probably unclear. I’m deciding between these options. Is there an advantage of using option B? This is a view from the top. Note that the background will ”leak”. Option A will (also) drain water that hasn’t passed the weir. This is true for B as well, but I think a larger proportion will since it will only drain from the surface.

 

[commod0re]

If you do B but use an external overflow box like @X-37B suggested then you won’t have to worry about any “leaking”

 

[BoxH]

Nice stand! It looks great. This should be a fun build

Whenever I build printer frames out of aluminum extrusions I use an engineer square to check each corner in all three directions and rarely end up with much more than a tenth of a degree of skew so that’s what I would suggest doing. Check (and adjust into square, if necessary) either the top or the bottom first and then use that as your point of reference for the rest

This is going to be a beautiful tank

 

[keepingwater]

And so the leveling issues begin…

I put on the top today, and as I had feared it only rests on the short perpendicular braces and not the main frame. I don’t know why this is, but I could see while assembling that the braces protruded a little. I can’t do much about it since the legs and the t-nuts in the slots determine the alignment. There is a gap of about 3 playing cards around the whole frame.

The sides of the tank will rest on the frame, so the question is what to do now. One option is to ignore it. The frame protrudes 4.5 cm from the braces, so there is 4.5 cm unsupported top. It’s a 3 cm bench top, and I can’t really see it deflecting under load for such a short distance. But I’m not sure :)

The other option is to shim it. Easiest would be to run a bead of silicone or similar on top of the frame. Or to use a few layers of tape. What do you think? It’s like 8 meters that needs to be shimmed, so not keen on using small plastic shims.

 

[keepingwater]

No thoughts? Maybe I was unclear, the issue can be summarized as ”is it fine that the top that the tank rests on is unsupported for 4.5 cm along the whole length (3 cm thick fiberboard top) or do I need to shim it”.

 

[UncommonSense]

No thoughts? Maybe I was unclear, the issue can be summarized as ”is it fine that the top that the tank rests on is unsupported for 4.5 cm along the whole length (3 cm thick fiberboard top) or do I need to shim it”.

What about shimming under only the long horizontal frame rails? It’s already so close that you may-well have fastener wiggle room there!

 

[keepingwater]

That would maybe work, but it would involve a billion fasteners and I would have to remove and readjust several of the panels (which were a bit painful to get in place). It would be a neater solution, but shimming with tape or similar would be much faster. What I should have done originally is to bolt a temporary alignment plate to each pair of profiles before connecting them. Not sure it would have helped though.

I think the root cause could be that the slots on the 45 mm side may not be exactly the same distance from the edge as the two slots on the 90 mm side are. Then that error translates throughout the build somehow. I just assumed that they would be.

 

[UncommonSense]

I think the root cause could be that the slots on the 45 mm side may not be exactly the same distance from the edge as the two slots on the 90 mm side are. Then that error translates throughout the build somehow. I just assumed that they would be.

It’s unlikely, but manufacturing error could attribute to this, too! — if the slots on one rail face are off by a few thousandths from the other face, errors start to stack!

 

[keepingwater]

I decided to shim it after all. I still don’t think the benchtop would deflect, but I’d rather see that more of the load goes through the long rails since that’s how I designed it. Only 5 out of 9 or the short rails are supported by a leg and the remaining ones weren’t designed to have a lot of load.

I ended up using this 0.7 mm hole band. It was cheap and the dimensions are consistent, but it’s zink plated rather than stainless, so I could maybe run into rust issues if I change to saltwater later. Cross that bridge when I get there :)

 

[keepingwater]

Some small progress on the sump. I’ve 3d printed holders for multiple sheets of 30 ppi foam. I’m a huge fan of having tons of foam for my sumps. It’s massive overkill wrt the nitrogen cycle, but it makes for really clear water. The foam gets colonized by bacteria that form biofilm and suspended debris sticks to it and gets broken down (”nitrate factories” is not a problem in freshwater tanks :)). I had a similar setup in my previous tank and I did zero gravel vacuuming or filter maintenance for the three years it was up.

After the 6 sheets of foam I’ll have a fine mesh filter sock for capturing the finest particulates after it’s broken down in the foam. Then I’ll have a UV sterilizer and some activated carbon. Since this will be a ”dirty” tank it’s really important that the water looks pristine. In my mind it makes the difference between a tank looking dirty as in nature or dirty as in neglected.

Next week I’ll have a plumber install the water line for the drip water change system and after I know where the drain will end up I’ll drill the tank and install a glass divider for overflowing into the filter sock.

 

[keepingwater]

Done with the stand! I went for a ”soft industrial” look with exposed casters and fasteners to complement the exposed grill of the dehumidifier.

Overall it went well, but I made a mistake when I ordered the profiles that came back to bite me. Between the legs towards the back there are horizontal profiles to prevent racking. I designed those to be an exact fit, but I should have left some clearance (like a millimeter each). I was planning to do so but forgot when ordering. This led to too tight a fit, and the outermost legs bend a little. It’s only a couple of millimeters, but it was still annoying since you can’t really adjust anything with aluminium profiles. A learning for next time (hopefully never) it to add some clearance so that the system doesn’t become overconstrained.

 

[commod0re]

Wow that’s looking great! Super clean with the panels on. Too bad it’s a little overconstrained but at least that’s pretty well hidden now

I mentioned/showed this thread to my wife and she thinks it would be cool if you shared some of this on the Aquarium Co-Op forum too, and I promised to pass that along

 

[keepingwater]

Wow that’s looking great! Super clean with the panels on. Too bad it’s a little overconstrained but at least that’s pretty well hidden now

I mentioned/showed this thread to my wife and she thinks it would be cool if you shared some of this on the Aquarium Co-Op forum too, and I promised to pass that along

Thanks! Nothing that a few carefully placed spacers can’t hide :) Everything is a good fit now, it was just needlessly cumbersome to get there.

I think of Aquarium Co-Op mainly as a forum for beginners, but I may well be wrong there. Also not loving the commersial aspect of it. But I’ll have a look!

 

[commod0re]

In many of the same ways R2R is also “for beginners” but neither forum is exclusively for beginners. Anyway I have no horse in that race, somewhat selfishly I have been enjoying seeing your build thread progress here :)