Questions regarding bracing and tank safety.

[SamMule]

I have a new aquaeon 75 that I am putting together. 48x18x21". Glass appears to be 6mm. According to the aquarium safety calculators i can find, 6mm glass at 21" high on a 48" span is considered unsafe. <2 on the safety index.
Obviously, the plastic rim and brace adds something, but how much?
It seems quite flimsy and ist really attached securely.
Would a eurobrace or two top braces be stronger?
Had anyone checked to see if thier 75g aquaeon bows?
Starting to have second thoughts about this tank.
Rambunctious toddler and questionable tank quality is giving me anxiety thinking about 75g of saltwater in my living room.

 

[shwareefer]

I have a new aquaeon 75 that I am putting together. 48x18x21". Glass appears to be 6mm. According to the aquarium safety calculators i can find, 6mm glass at 21" high on a 48" span is considered unsafe. <2 on the safety index.
Obviously, the plastic rim and brace adds something, but how much?
It seems quite flimsy and ist really attached securely.
Would a eurobrace or two top braces be stronger?
Had anyone checked to see if thier 75g aquaeon bows?
Starting to have second thoughts about this tank.
Rambunctious toddler and questionable tank quality is giving me anxiety thinking about 75g of saltwater in my living room.

Any chance the tank is tempered? That would change everything.

 

[EeyoreIsMySpiritAnimal]

.

 

[SamMule]

I don't know. It's a brand new aquaeon 75. Doesn't appear to be. Passes the sunglasses test with my tablet inside.

 

[PotatoPig]

I suspect the calculator is assuming a rimless tank.

In a rimless tank the glass spans horizontally from one end to the other, with help from the bottom. If you play with the numbers in a rimless calculator you’ll see the longer your aquarium the thicker the glass needs to be, even if it’s not getting deeper.

The brace in the middle changes this completely. Instead of spanning the length of the aquarium (48 inches) it spans the height (21 inches) so is under much lower stress.

This is why you’ll also see two braces on the even longer framed tanks - if you just had one you’d start to get horizontal spans again, so they add extra restraints to keep the spans down.

 

[SamMule]

Would removing the plastic rim and adding two glass braces be stronger?

 

[PotatoPig]

Would removing the plastic rim and adding two glass braces be stronger?

Theoretically…. Maybe, but you’re also messing with how the ends tie together and are relying on the cements you’re applying and making the tank work a little differently from how it’s designed. No way on earth I’d do it. Maybe others who have modded tanks can weigh in.

I’d also worry messing with the frame would mess with how the top of the glass is in compression as the tank spans from end to end to carry gravity loads. Without the angle you’re potentially making the behavior of the top of the glass more slender and prone to buckling.

Two things to consider:

1. Filled to the absolute brim the top brace only has something like 60lbs tension in it. This is pretty low. The loads really aren’t that much to get this setup to work.

2. There are a LOT of these tanks out there. A lot a lot. Check out your LFS and they’re almost certainly using these framed tanks. Seeing probably heavier use and more “knocks” than most home aquariums. Also take a look at how they’re supported - most likely only at each end - critical to their behavior when building a stand for one.

 

[SamMule]

Theoretically…. Maybe, but you’re also messing with how the ends tie together and are relying on the cements you’re applying and making the tank work a little differently from how it’s designed. No way on earth I’d do it. Maybe others who have modded tanks can weigh in.

I’d also worry messing with the frame would mess with how the top of the glass is in compression as the tank spans from end to end to carry gravity loads. Without the angle you’re potentially making the behavior of the top of the glass more slender and prone to buckling.

Two things to consider:

1. Filled to the absolute brim the top brace only has something like 60lbs tension in it. This is pretty low. The loads really aren’t that much to get this setup to work.

2. There are a LOT of these tanks out there. A lot a lot. Check out your LFS and they’re almost certainly using these framed tanks. Seeing probably heavier use and more “knocks” than most home aquariums. Also take a look at how they’re supported - most likely only at each end - critical to their behavior when building a stand for one.

Yeah, I suppose you're right about there being so many out there and the abuse they take. If it was that poor of a design, they wouldn't be making them anymore. Probably just over-thinking it and worrying about nothing then.

Maybe I'm misreading your last comment, but you're saying LFS tanks are only supported on the ends? That doesn't seem right. Every stand I've ever seen has support for the entire perimeter of the tank.
When I built my stand, I made sure it was perfectly level and square with support all around the perimeter of the frame.
Hasn't been wrapped yet with the finish, but it's hell for stout.

 

[vetteguy53081]

I have a new aquaeon 75 that I am putting together. 48x18x21". Glass appears to be 6mm. According to the aquarium safety calculators i can find, 6mm glass at 21" high on a 48" span is considered unsafe. <2 on the safety index.
Obviously, the plastic rim and brace adds something, but how much?
It seems quite flimsy and ist really attached securely.
Would a eurobrace or two top braces be stronger?
Had anyone checked to see if thier 75g aquaeon bows?
Starting to have second thoughts about this tank.
Rambunctious toddler and questionable tank quality is giving me anxiety thinking about 75g of saltwater in my living room.

This applies to rimless and Few if any aqueon tanks fail as it meets requirements for holding water. Ive yet to see them bow as the bracing is thick and adequate

 

[PotatoPig]

Yeah, I suppose you're right about there being so many out there and the abuse they take. If it was that poor of a design, they wouldn't be making them anymore. Probably just over-thinking it and worrying about nothing then.

Maybe I'm misreading your last comment, but you're saying LFS tanks are only supported on the ends? That doesn't seem right. Every stand I've ever seen has support for the entire perimeter of the tank.
When I built my stand, I made sure it was perfectly level and square with support all around the perimeter of the frame.
Hasn't been wrapped yet with the finish, but it's hell for stout.

See this example: https://www.reef2reef.com/threads/d...y-flat-must-the-stand-be.861459/#post-9401240

If you go to your LFS they’ll probably have tanks stacked on the wall, apparently with angles under. Take a close look at the angles - there’s probably a gap. The photo below is from a 6ft framed tank - you can’t see it in the photo but there’s about 1/8” clear underneath the length to the ends. Although that’s a little beside the point even as the angles are too tiny to carry loads.

Similar with the commercial stands you see - they’re often designed so there’s a gap between the tank and the sides, with support only at the corners.

Even the wood frames (my 75 gallon is on very similar to yours, I took the same RocketEngineer design. It’s sturdy) the long members can’t support the glass. It’s not possible for them to carry the load because the glass pane is approximately 20x as stiff as them. For the 2x6 to carry the load the glass pane above would have to bend less than the 2x6, but it’s much much more rigid.

The critical thing when setting up the stand is that the four tank corners need to be in contact with the stand, because that’s where the loads go.

 

[SamMule]

Thanks for the clarification. That's very interesting! We don't have any big stores like that up here, so I've never seen anything like that!