180 Gallon DIY Stand Design Questions

[Sarlindescent]

The stand has a 2x8 top frame and 2x4 everything else. Stand is about 6'6" wide. I plan on adding mitered 2x4 triangles to the top and bottom of all the rear supports to prevent any movement. Trying to build the stand without a center brace. Will this hold? Also, plan on gluing plywood to the top and bottom. What is the preferred thickness 1/2 or 3/4? Tank is acrylic

The right side of the tank will have a synergy reef ghost over with a beananimal design into a diy w/d filter in a 75 gallon. This is what I plan to use for the w/d: https://www.amazon.com/dp/B00IKAF6HY/_encoding=UTF8?coliid=I33PBR7ILN06MM&colid=ZHTNXPNL2V45 . W/D will be on a stand off so the water line in that area is below the top of the bottom drawer. Plants will be grown in the rest of the sump. Is this enough filtration?

Lastly, I am considering running a 1" bottom drain to a Cepex ball valve with a Barb fitting. Basically, when doing water changes or a full empty, hook a hose to the Barb, open the valve, and easy water change. Plus when I move, this will make draining the tank trivial. Is there much risk to this leaking?

Note: This is my first time using sketch up. Please ignore the mistakes. The support braces will be evenly spaced and the 2 vertical supports on the right side of the tank will be aligned with the corner of the platform.


Planned scape:

 

[freak78]

So essentially your wanting to do this.
this isn't my pic I just got it off the internet. Well since you have vertical supports across the back and are using a 2×8 for the top rail I wouldn't think there would be any issues.

 

[Drstrangelove]

I'm assuming a dead load of 1,800 lbs and using wood beam capacity tables. Obviously your table is not exactly covered in the tables, but they might be suggestive.

It looks like you are using single 2x8's. Assuming you add the angles for lateral support, I'm thinking you might want double 2x6's, (or even double 2x8's), not single 2x8's to bridge the span. Especially in a condition where water is routinely close by the structure.

That might be overkill, but the span tables I have access to seem to suggest single 2x8's could be undersized in this case.

The example Freak78 found actually appears to do the same as it appears to be using double 2x8's. In either case, I would consider whether a single 2x8 is adequate to cover that front span. Adding more support under the front span is obviously something you might prefer to avoid, so the beam might need to be stronger.

You might want to consider (if you haven't) preparing some sort of water repellent for the wood under the tank as otherwise, that might become an unwelcome issue down the road.

 

[Sarlindescent]

Thanks for the replies. I plan to use kilz on the inside to waterproof everything but the outside of the wood for wood glue to attach the skin. Also, the bottom sheet of plywood will be siliconed to the frame, preventing water from escaping the stand in the event of a leak (this provided at least 20 gallons of containment). Planning on wrapping the stand in 1/2" plywood and skinning it most likely with cherry veneer. In terms of the dead load on the tank, it is around 1600 lbs (tank+water =1535, and fairly minimal scape weight.

My two weakest spots from what I can see are clearly the unsupported 2x8 65" span in the front and the right side of the tank not having an unsupported center brace. The w/d filter will be in the way, so not sure if I can add a miter joint to that.

 

[FAT daddy]

I would keep the brace just to be safe...

 

[BIG-G]

Is the open span so you can insert and remove the sump?
If so you could use a removable supporting post. Put it in place with screws.
But I don't think that it's going to be a problem.
You could do as drstangelove suggested and double up the beam.
I had a 16 ft span to cover on a front porch for the roof to be the way I wanted. The engineer designed a beam with two 2x8 with a sheet of 3/4 inch osb sandwiched between the two they were glued and screwed. He said the osb would add an extreme amount of rigidity. It's been 10 years and this beam has not moved.
I believe that a lot of span beams are being designed in this manner now.