(55 gallon) how much bowing of tank is within reason?

scottishduck

tl;dr at bottom

I got a 55 gallon tank for free on craigslist and fell in love with the dimensions (48x15.5x17ish). It's deeper and shorter than a regular 55 and is nearly approaching the breeder level of floor space. I like this for the aquascaping capabilities. I think it was made as a terrarium, however. There is no center brace on the tank. The glass is about 6mm (I think. It might only be 5mm, which would be potentially be a problem). I stripped the silicone and resealed the tank. I then filled it with 3 inches of water and there were no leaks. I then filled it half way and there were no leaks nor bowing. So I filled it all the way up. The top and bottom frames are perfectly straight. The ends are straight (as I can tell). And the middle center of the front and back panels bows by approximately 1/32" .. maybe a little more (it's less than 1/16" at least). Is this slight bow something to be concerned about?

I'll keep monitoring over the next week to see if it worsens. I don't expect it to though, since if the glass fails I expect it to fail fantastically all at once.

tl;dr: 48" long tank, 17" tall, bows about 1/32" in the center of the pane. TrI'm keeps top and bottom from bowing. is this okay?

Thanks in advance!
 

BluMan1914

Hmmmm...that's a tough one. I don't trust a tank that bows. If you can try and put a center brace on that tank just for the piece of mind.
I'm just a paranoid person, and just the thought of a tank bowing, will keep me awake.
Better safe than sorry.
 

Claire Bear

I agree with BluMan1914. A bow is never a good sign and has the potential for increasing and failing over time. I would use it as a reptile enclosure or some other purpose but I would not use it as an aquarium.
 

Aquaphobia

Yeah but a small amount of bowing is to be expected. Is it possible to add an aftermarket brace?
 

scottishduck

I don't think a brace would do anything because there is no (noticeable) bow at the top of the tank. If it's not bowing at the trim, I don't see how a brace on the trim would help anything.

Really, the only way to tell that there is a bow is with a 2' long straight edge. With a regular 1' long ruler there's no bow. I'll get a picture tomorrow morning (when there's sun again - it's outside because I'm not stupid).

Edit: I'm not against bracing it... but would it do anything if there's no bowing at the trim at all?
 

TexasDomer

I wouldn't use it as an aquarium either. I don't thinking any amount of bowing is normal, and I'd worry about the glass width.
 

Aquaphobia

True, I was thinking more for peace of mind.
 

BluMan1914

Aquaphobia, you can either DIY, or just buy a rI'm with a center brace. I agree, a very, very small amount of bowing is expected, but I get the feeling that the bowing in this case is noticeable by the eye, to me that is a big concern.
 

Aquaphobia

Even though a straight edge has to be used to detect the bow as in post #5?
 

BluMan1914

No. My post went up after the OP stated that the bow isn't noticeable by the eye.
Like I said, I'm just paranoid. If I have any type of concern, especially in this hobby, I would never feel comfortable. I'd rather have the peace of mind, than worrying about something.
 

Aquaphobia

I'm still quite sure that glass tanks have a certain tolerance for bowing when filled. I'll have to look around for the place I read that though!
 

scottishduck

I'm still quite sure that glass tanks have a certain tolerance for bowing when filled. I'll have to look around for the place I read that though!
That's the kind of info I'm looking for. I have no immediate plans for anything, so it's not like I need to know right now. Like I said though, it's less than 1/16" and I need a straightedge to tell.
 

Aquaphobia

Still looking. A quick search found about an equal number of pages for and against.
 

BluMan1914

Sooo...after about an hour of so of researching the internet. There are different opinions on bowing, some say it's normal, but the majority says it's risky, and that it should have a brace. I believe that over time that bow may get worse. I guess right now it's up to you, and what you are comfortable with.
 

Aquaphobia

I ran it through the calculator at garf.org and came up with a glass thickness of 1/4" which is 6.35mm. I would grab some calipers and check the thickness of your glass to be sure. I think that if it's less than 6 I wouldn't use it.
 

scottishduck

Drained it. Will add brace and see if it will work. Otherwise will try to sell as terrarium on craigslist for 20 bucks or so.
 

BluMan1914

I just read about euro bracing, which seems to be a very good way to brace your tank, but there are several ways to do it, and what type of material to use. Just research and see what's convenient and easier for you.
 

scottishduck

Eurobracing will be too expensive. If I can't brace for less than $55, I'll just buy a tank at the petco sale.

I'm currently thinking of securing a piece of 1/4" acrylic to the underside of the frame; maybe with teflon screws, maybe with a liquid adhesive.
 

BluMan1914

Wish I could find it for you..but I also read where one person just used a piece of plastic, or acrylic for the brace, and another used stainless steel. I'm sure there a cheap and safe ways to brace it.
 

martini4

Go to NAPA and ask them for part number 732-1240. It's an exhaust hanger that fits perfectly over the center of a 55. That's what I did on mine....until my silicone job gave out when my toddler climbed on the table and used the top of the tank to pull himself up, but that was on the side, not the front.
 

scottishduck

Also, I've checked with different places online for a replacement frame with a brace, but since it's not a standard size (15.5" deep and not 13" nor 18") no one can get one.

Thanks for the options, I don't think I want to put metal as the brace due to rust/etc. I plan to make it brackish and open top... so I don't think metal is the best course of action.
 

Aquaphobia

Can't you just use glass to brace it? Or get clear acrylic and a heat gun and bend your own
 

bigdreams

How thick is the glass? Also, you can buy a new tank at PetCo for cheap right now. I think spending $40 for a 40 gallon breeder is worth it for peace of mind
 

scottishduck

Since this thread just got a new like, decided to update everyone.

I got some acrylic in to cut to size for a front to back brace. I'm going back and forth on a 4" vs 6" wide brace.

I haven't done anything because my life has been hectic and we keep having visitors come by. I may do something next week though and will keep you updated.

For reference, when I decided to check the front to back measurements with a ruler (rather than looking for bow with a straightedge) when filled there was a 1/2" difference from the corners to the middles. This means that each pane was bowing 1/4". I will try once to fix it with a brace, and if I can I will let it sit for a while to see if it holds. Otherwise I will come up with a new plan for it.

Thanks for all the advice in this thread.
 

scottishduck

UPDATE:

I added a front to back 4" brace in the center. I used 1/4" acrylic and secured it to the frame with scigrip 16. It's holding water great. I've also had to refurbish the old Eheim 2217 and now it's functioning well. I now have to finish the plumbing, build a stand and see where it goes from there. Just wanted to update everyone that the center bracing hasn't budged in over a week and it's been full of water the whole time.

EDIT:
I'm leaning brackish: orange chromides and bumblebee gobies.

I have everything set up so the only thing in the tank will the intake and output from the canister filter, and MAYBE an in tank UV sterilizer. I have made a DIY inline housing for the thermometer. I also found a SCWD cheap to add to the outputs for more of the surge-like random flow nature of an estuary. I'll post a new thread with my ideas in the tank builds though. So this will be my last post in this thread except to add a link to the new one when I decide to set it up for real.
 

Green Knight

This is what Aquael say in reply to my concerns about bowing fish tanks:
'Aquael is manufacturing aquariums according to DIN German aquarium standards, which describe thickness of glass vs. volume of tanks.
Therefore the aquariums are safe.
We are aware that due to pressure of water aquarium glass can bend 3-3,5 mm on every side, but is it absolutely safe and since we started production 2 years ago we haven't had any claims on break of the glass.
At this size of aquarium (W75 x D35 x H40cm, 105 litres) there is not needed any extra glass supports.
 

AquariumX

29g Aquarium is the largest that is constructed without a brace. If your 55 gallon does not have a brace, it was probably not intended for use as an aquarium.

29G Tanks have some bowing, but a braced 55 shouldnt have much if any visible bowing.
 

Piaelliott

29g Aquarium is the largest that is constructed without a brace. If your 55 gallon does not have a brace, it was probably not intended for use as an aquarium.

29G Tanks have some bowing, but a braced 55 shouldnt have much if any visible bowing.

A 40 gal breeder doesn't have a brace either.
 

AquariumX

UPDATE:

I added a front to back 4" brace in the center. I used 1/4" acrylic and secured it to the frame with scigrip 16. It's holding water great. I've also had to refurbish the old Eheim 2217 and now it's functioning well. I now have to finish the plumbing, build a stand and see where it goes from there. Just wanted to update everyone that the center bracing hasn't budged in over a week and it's been full of water the whole time.

EDIT:
I'm leaning brackish: orange chromides and bumblebee gobies.

I have everything set up so the only thing in the tank will the intake and output from the canister filter, and MAYBE an in tank UV sterilizer. I have made a DIY inline housing for the thermometer. I also found a SCWD cheap to add to the outputs for more of the surge-like random flow nature of an estuary. I'll post a new thread with my ideas in the tank builds though. So this will be my last post in this thread except to add a link to the new one when I decide to set it up for real.

MAKE ABSOLUTELY SURE THE BRACE WILL NOT COME UNDONE. MAKE A MECHANICAL CONNECTION. IF YOU USE GLUE AND IT COMES UNDONE, THE IMPACT WILL BE LIKE HITTING THE TANK WITH A HAMMER!
 

Aquaphobia

Depends on the construction. Old style tanks are made with such thick glass that they don't have a brace either. I have an old 80 gallon (not currently in use) that's made with 3/8" thick glass and no brace
 

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