Building an acrylic top for tank

[ejmeier]

How do you do this?

I am going to make a 60g cube, so dimensions would be 24" x 24" x 24", probably with 3/8" Acrylite-GP. I don't really see the need for a center brace, given that it is a cube; but how exactly do I go about making a top for a tank like this? I have heard many methods, but want to know what is most common, particularly for cube tanks.

I would like to be able to have a fair amount of room to put in LR and do maintenance, so I was thinking to put a lip around the top of the tank, maybe 3". For a DIY project, and to conserve wasted acrylic, I don't think that I would want to buy a 24" x 24" piece of acrylic and cut out half of it to be scrap.

Any suggestions or methods to be used would be great.

[SeanT]

By 'top' do you mean to cover the tanks opening or 'top' as in something to hold lights.

[ejmeier]

I mean an acrylic top that is solvent welded onto the tank to improve structural stability.

[rpgraff]

Are you worried about bowing with 3/8" acrylic? I'm asking because I'm working on plans that will utilize a 24"x24"x24" tank and if I decide to use acrylic I was under the impression I should do it in at least 1/2" acrylic.

As far as a top for support, I was planning to use a piece the same size as the bottom and cut an opening in the top that left a 1" lip or so.

[ejmeier]

rpgraff - I am not too concerned about bowing, but if you're going to only have a 1" lip then you would probably want to do 1/2" acrylic as that is almost an open top. I plugged in the numbers at Cyro's site, which I consider to be way overkill, and it gave me something like .46.." thickness. Even Cyro's site didn't say to use .5" acrylic, and after adjusting for their overkill, I just came up with the 3/8" (.375") thickness.

Anyway, am I the only one who thinks that cutting a sheet of acrylic the same size as the bottom piece, then removing 75% of it, and calling it a top is wasteful. There has got to be a better way...

Can't somebody recommend something to me for a top?

[Zephrant]

In this thread: 100g Sump (http://archive.reefcentral.com/vbulletin/showthread.php?s=&postid=714018#post714018)

I show some pictures of a top that is pieced together. It needs to be reinforced with gussets in the corners, but it works well.

Zeph

[ejmeier]

Thanks to all who helped, and thanks for that link Zephrant - although I vaguely remember reading it earlier too.;)

I have made a plan, which is attached below. Please let me know right away if you see any flaws or anything in it as I'm planning to order the acrylic tomorrow.

Basically it is going to be two layers of 1/4" Acrylite-GP glued together to form a 1/2" top. I am thinking of a 3" lip, but may bump this thickness up to 4" or more if I think it is necessary. I made it so each piece of acrylic is supported by two sides of the tank - this should help with the sturdiness. Please see attached pic.

[Zephrant]

I'm not sure how easy it will be to laminate that up. I would only attempt it if I could vacuum bag it, and even then, I'd look for an easier way.

You might try to pick up some scraps from an acrylic shop that is thick enough, then just butt the edges together. Add a gusset under them so it overlaps the joint, and you would be plenty strong enough.

HTH-

Zeph

[Acrylics]

Originally posted by ejmeier

I have made a plan, which is attached below. Please let me know right away if you see any flaws or anything in it as I'm planning to order the acrylic tomorrow.

Basically it is going to be two layers of 1/4" Acrylite-GP glued together to form a 1/2" top. I am thinking of a 3" lip, but may bump this thickness up to 4" or more if I think it is necessary. I made it so each piece of acrylic is supported by two sides of the tank - this should help with the sturdiness. Please see attached pic.

IMO you are creating alot more work for yourself for a weaker piece of plastic.

You are still buying 4 sq ft of material (8pcs x 3 x 24=4 ft).
You create a real headache of a lamination job as the 1/4" (actually 6mm) is a nominal thickness and will vary by up to or over .020" in the size you are specifying - making a good lamination even more difficult than a 72 sq in lamination job would normally be.
The lamination will also make gluing to the tank more difficult as you will have two things going against you; the first being the thickness variation will make gaps in the joint, and thin laminated surface tend to bow (alot) making this joint more difficult.
The top brace itself will not be as strong as you will have sharp 90 degree corners in each corner rather than radii, even a standard 1/2" flush cutter will leave a 1/4" radius - much stronger than this sharp corner.
Besides all this, what you are outlining simply takes much more time than the $10 savings warrants (IMO).
IMO/IMO, there are reasons we build tanks the way we do, it's stronger & faster, therefore cheaper to just do it out of single piece. plus it simply looks better. It may seem wasteful to cut out 2.25 ft of material but it does make for a better tank and you can use this piece for other projects as they come along.
The 3" flange all the way around sounds great, makes a nice 18" square cutout - if you can put a larger radius on each corner - all the better.

HTH,
James

[ejmeier]

Well...

I'm probably just going to use one solid piece of material now.:D

My only question is that if there is a 3" or 4" lip going around the whole top of my tank, using any top, how I am able to access my overflow box? I was planning a corner overflow maybe 4 - 5" square, but with the top covering this, I won't be able to service/install a standpipe. Should I simply make the overflow bigger?

[Acrylics]

Originally posted by ejmeier
Well...

I'm probably just going to use one solid piece of material now.:D

My only question is that if there is a 3" or 4" lip going around the whole top of my tank, using any top, how I am able to access my overflow box? I was planning a corner overflow maybe 4 - 5" square, but with the top covering this, I won't be able to service/install a standpipe. Should I simply make the overflow bigger?

This is one option...
...or....
Make the flange on the O/F side wider such that you can put a second hole in the flange where you want access to the O/F.
ie.,
Make the general access cutout in that corner a 45deg cutout. The rest will stay as normal. The large access hole would look like a square with one corner lopped off, then with a second hole in the corner over the O/F.

HTH,
James