Fish tank design - bottom panel.

Ok hi all. I am new to the forum. Kind off,
Ive been a "roof kyker" for a while but i am in the need of the wisdom od this forum. I have a 3ft setup currently and i want to go big . More than 7ft at least for an arowana. On a tight budged i need to het thinner glass and brace it properly. I have done my research and uses the calculator on this forum which is in line with other web based calculators.(forum wisdom).

Now here is my question. Can i use a thinner botton pane (9mm vs 12mm), If my tank will be placed on a 30mm solid wood plank?
Thanks in advance

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Hi and welcome. As far as I know, using a thinner bottom panel will make it a weak point and it could crack if the pressure is too high.

Also where are you based?

 

Hi and welcome to the forum. IMO I will go as save as possible and rather go as thick as possible. Bracing might solve some problems regarding pannel strengh but I have read from other forum members who have arowanas that the bracing causes damage to the fish. Maby @MariaS and @BoelderBeesty can give some good advice here

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It all depend on your stand, does it have anough cross bracing to distribute the weight evenly across the lengh? Also I would use thick polystyrene between the plank and tank. I am running my 2m tank (10mm glass) for a couple of years now with the plank and polystyrene combination and so far no cracks or leaks.

 

@BoelderBeestie

 

Thanks it is helpfull. I'm planning a nice and sturdy rectangular tubing with cros braces every 400mm

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@Pierré Schoonraad ... Its a fine line to make a decision on not bracing in order to protect the fish....
I, or rather, @Cesar made the mistake once with his first 2.3m tank.. it wasnt braced.... one day we walked in from work and the tank was less than half full and the fish including Dragon, were all dying.. we were very lucky.. in the end he only lost one geo
The tank had given way on the bottom joins....
We had that tank rebuilt which is the one i am using now but i had it braced top, bottom and the sides as well as a floating base
You cant go that big and not brace... its asking for disaster sooner or later..

As for the arowanas.. We have 4 arowanas
Silvers...usually become a handful and tend to spook a lot easier than asians.. they do jump but, they also sometime dash across the tank so.. yes they can hurt themselves but usually its not so bad that it doesnt heal.
If you really want to, you can put some sponge on the bracing to protect her but we have never done it and never had serious injuries. Its mostly a scratch and missing scales which grow back pretty quick.
Dragon has broken through the sliders at least three times and only had a few scratches

The Asian arowanas, are a little nervous at first but once they get to know you and settle down they no where near as bad as silvers
Dont get me wrong, they still jump but, at least ours, dont do it often
In summer i have to be careful, Flash will jump if moths go to the tank lights at night but otherwise she doesnt jump a lot.

@B@kkies .. I am not a tank builder.. but on a 2m tank.. I definitely wouldnt go thinner than 10mm or if possible 12mm but, i guess after what happened to us i am very scared although it was the lack of bracing that caused the problem also as @BBFish said, polystyrene between the glass and the wood plank

 

And.. @B@kkies... Welcome to the forum.. glad you came down from the roof!!

 

The key to a hassle free tank .... most factory made tanks are floating base - even my little Perfect 10's are. It is a must for bigger tanks. The last thing you want it the weight from the panels causing issues in your life.


The salt guys love looooong debates bout glass - here is an example, I am sure if you go digging - you might even see them talk about the base in sections and sandwiched. https://www.marineaquariumsa.com/th...ess-on-a-brace-less-rimless-tank.48280/page-2

Later Ferdie

 

Oh yes .. sometimes you just have to do the math yourself to understand the problem ... https://aquariumworld.nz/fish/artic...alculating-glass-thickness-for-aquariums-r23/ should give you a good start.

Later Ferdie

 

Hi thanks allot for the note of welcome and advice. Im contemplating using using a yoga mat instead of the polistirene. My argument is thare should not be any high spots on the wooden plank to create pressure points and the polistirene will allow the bottom panel to sag in the middle and make it weaker. I must say i am nervous to test my theories in practice.

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I share this theory. If the base is propperly supported it will see more static pressure and less shear stresses where glass thickness is important

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Oh yes.. i fully agree with that.. no doubts there.. my stands run supports at every 40cm
However, despite that, personally i would still not go below 10mm on a tank that size...

But this is my personal opinion based on past experience... the final decision is yours and we respect it.

 

I have already got glass 9mm. If i buy another 9mm and put it below the panel i have, will that work? My thoughts were then to use a epoxy i used on a carbon fibre project which is extremely thin and thus create a 2 ply laminate. This will save some money

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Yes, you can put 2 x 9mm panels together at the bottom, i have 3 x 10mm panels

I am not sure about the epoxy so dont want to give wrong advice,,, lets see if one of the guys with more experience in building tanks chimes in..
My panels, they used the same silicone as used on the tank
When they came out and built my son's on site, they also used the same silicone as the tank to glue the bottom panels together
They didnt spread silicone completely all over the panels, they just put lines of silicon on the bottom one and then pressed the second one to it.

Sorry for changing the subject... is that a scat on your profile picture?

 

Yes. It is on my wishlist. Thanks lets wait for the other experts on epoxy.

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That is a stunning scat.. hope your wish list materializes.

 

Only saw this post now. I had to wrap my bracing with a piece of foam(yoga mat). My silver(60cm) tend to swirl at the surface and also break the surface while feeding. He used to hit the brace even with 10cm head room. This knocked off scales on his back and head, after the foam wrap he can hit that brace as hard as he can without damaging himself. He just bounces off it.

Go thick on the base if you can, when the aro gets big he knocks the tank around pretty badly. I'm no expert on tank building but I wouldn't feel comfortable with a thin base on a aro tank. Mine makes the tank sway after a big hit, not sure if it would flex and warp the bottom or not but rather safe than sorry.

As far as epoxy goes, I've worked with it a lot but on model aircraft not tanks. Epoxy does not have the flex like silicon has, it sets hard and doesn't give, that's why we use it for motor mounts on the models and center wing joiners. I don't think it would work for glass but not sure. It also heats up during curing. I think it will be too hard to work with glass and will also not "grip" it well. When I'm done with a batch I made the leftover sets in the mixing bakkie and you can pop the whole thing out like a slab with a light tap, silicon won't do this.

 

Thanks for chiming in there @BoelderBeestie ... yep... very scary what they can do and the power they have.. you must imagine what it becomes like at 97cm..

Your comments on the epoxy is more or less how I looked at it..

 

@MariaS looks like Saturday my arowana days are over, so sad. I've sold the aro and oscars, taking them away on sat. Feels like I just broke up with a girlfriend haha.

I'll definitely get one when I'm a home owner and can have a monster tank built in but with the "normal" large tanks that fits through a door it's not possible to keep the silvers. They just get too big and strong.

His tank was 1.8mx60cmx60cm, that won't cut it anymore.