Is a 2x8 top frame enough?

[Tuffloud1]

I'm questioning whether or not my 2x8 with no center brace on the back top frame of my stand is sufficient. I'm worried about deflection, not a total failure.

Tank is 72x28x30, 262 gallons

550 pounds empty

I got info from one of RocketEngineer’s threads that a 2x8 header will work.

Here are pictures of the measurements from the middle of the 2x8 before and after I filled the tank with water 7 inches from the top.

Should I reinforce it better?

 

[Tuffloud1]

Anyone? Not sure what happened to Rocket Engineer.

I tried sending him a PM months ago, haven't heard back.

 

[mcgyvr]

I would not be worried...

 

[Tuffloud1]

I would not be worried...

So 1/16" is nothing to be worried about?

I assume that it will deflect even more over time (years and years).

 

[mcgyvr]

If it concerns you just sister another 2x8 on each existing...you wont even see it..

 

[Tuffloud1]

If it concerns you just sister another 2x8 on each existing...you wont even see it..

I guess the question is, why should I not be concerned about the deflection if it is already showing and the tank isn't totally full?

From my understanding, you want 0 deflection because we are supporting glass.

 

[wrott]

Isn't it 2 X 6'? What size are the planks, 2x6"?
And I would put a couple of 2x4s in the middle to secure it.

 

[mcgyvr]

Yes zero is ultimate but rarely achieved.. Some deflection is ok and the glass/joints can tolerate some...

1/16 over a 6ft span should be safe.. Sintering another board or adding a center support wont hurt and will reduce deflection..

 

[Tuffloud1]

Isn't it 2 X 6'? What size are the planks, 2x6"?
And I would put a couple of 2x4s in the middle to secure it.

It's a 2x8 but realistically 1.5x7.25.

I can't put a middle beam in as I am putting a 60 inch sump down there.

 

[Tuffloud1]

Yes zero is ultimate but rarely achieved.. Some deflection is ok and the glass/joints can tolerate some...

1/16 over a 6ft span should be safe.. Sintering another board or adding a center support wont hurt and will reduce deflection..

Would 3/4 ply glued and screwed work well?

 

[mcgyvr]

Would 3/4 ply glued and screwed work well?

To what/where?

Why not put the sump in place then add a middle support that could be removed if needed

 

[Tuffloud1]

To what/where?

Why not put the sump in place then add a middle support that could be removed if needed

3/4 ply glued/screwed to the face of the 2x8 (sistered).

I don't want a center support. Makes maintenance a nightmare.

 

[mjenk430]

Tuffloud1,

What did you end up doing for your stand to reduce deflection? I am currently designing a stand for my new 300 gallon (72"x36"x27") and don't want a center brace in the rear for sump access similar to yours. I also don't want a super tall top support to maximize space under the stand. I was considering using a doubled or even tripled 2x6 at the top for the clear span. What are your thoughts based on your experience with you stand?

 

[cvrle1]

RE is active on the other site, so he can be reached there. I did talk to him about center brace few months ago, and he said that 5 foot is basically limit of center vs no center. Since my tank is 5 feet, and I used 2x6 for the top, I added off centered brace. This way I had some extra support, but had enough room to fit a sump in without issues.