DIY Stand for Flatback Hexagon Tank

Cool_E-Loach

New member
Hello All! First post here so a quick introduction - Have had lots of freshwater tanks since I was a boy, got out of fish keeping for a while but took the hobby back up as a couples activity last year when we realized we both love the creative & scientific aspects of scaping & husbandry. So now there are planted FW tanks all over the house! I've been learning about & planning a saltwater tank for a while now, and am beginning to pull the trigger on my build. Reef Central has been a hugely helpful resource of knowledge, I hope to contribute to that!

For this build, I'm locking down some final details and hoping to get a sanity check from you experienced folks that this plan is solid. I've got a ~20 gallon flatback hexagonal tank that I'm going to use for a small mixed reef. Have some thoughts on livestock, mostly corals and an interesting CUC, will do a few fish but this is a tall tank and, like I said, it's only 20gal. Want to use a 10gal sump to add some volume to the system, but going to focus more on fish when I devote one of our 55gal tanks from storage to SW. This tank is pretty cool looking with faux wood trim. Haven't seen many of these and what I have is mostly acrylic & much larger. This one is all glass, seems like this may have been a more popular style a while back? The QC tag on the bottom is dated '93, so it's over 30 years old at this point! Structural seams looked good, but the interior seal was starting peel. $25 later for a pack of razor blades, acetone & a tube of silicone and she is resealed, no bad for a free craigslist tank. Just passed a 3 day leak test so I'm moving on to the stand build. That's where I've come to a question that I'm hoping for feedback on. Haven't found many folks online who've done builds of stands for these types of tanks. Buying lumber today so I'll turn this into a build thread over the next couple weeks as I work on it.

Conventional wisdom for a solid stand dictates you want full support under the rim of the aquarium, and then vertical supports under corners (and evenly spaced under any long spans) to ensure the weight of the tank is firmly transferred to the lower frame & into the floor. I use 3/4" plywood as a top, but the rim of the tank sits centered over a 2x4, on edge, all the way around. Simple enough! Now, if I were to do that for this unusually shaped tank, I would not have room underneath for the sump tank. Normally, that would convince me to change my plans and either use a HOB, or a smaller sump. However, Mrs.Cool_E-Loach would prefer a normal, rectangular stand to match the style of the other homemade stand this will be next to. Square corners are easier for trim cuts anyways, so I'm on board!

If I want to put this shape of tank on a rectangular stand, my thinking is that I can still put a 2x4 on edge under the front, back, and two of the sides. Because all of the points where glass intersects touch the outside rectangle, I could still put vertical supports at all 6 corners. With the 3/4" plywood top, the whole rim will be sitting on solid material, but the two angled sides would be sitting only on the plywood. Those would span about 7" each.

It would also be very simple to just add cross bracing 2x4s to the upper frame at angles to match those sides for extra support. Technically, any weight put on those would be reliant on the sheer strength of the screws, since they'd have no vertical supports. That's not a big concern given the small amount of weight involved. Really, these would be most useful as a place to shim any small bit of cupping out of the top so that the tank rim sits flat all the way around. No reason not to put them in.

Looking at this quick top-down sketch, I'm inclined to build the upper frame in the 'B' configuration, and then just do 'A' for the lower frame. Vertical supports between frames at every red mark. I'd add cross bracing to the lower frame and put a flat piece of plywood on it to support the sump. With conservative estimates for tank weight, water, rock, sand, & a HOB overflow, I wouldn't expect to be over 350lbs in total. With 2x4s on edge, I'm really no where near risk of failure. Over engineering a high safety factor helps me sleep at night, though! Could add a vertical support at the center of the 25" span, as well.

Really just looking to confirm that I'm not way off in my assumption that those having those 7" sides only supported on the upper frame (and 3/4" top) will be a non-issue. This seems trivial now that I've typed it all up, but might as well post to hear what others are thinking. Build pics to follow shortly!


Black - Tank
Grey - Stand frame
Red - Vertical support between frames
flatback hexagon tank stand.jpg
 
I like the looks of your design. I see no issues and believe me, I really believe in over building stands.
 
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