Silicone and bracing failure

[805hd]

Backfromthedead I spent a ridiculous amount of time scraping and scrubbing that tank to get all the old silicone off. My hands and back hurt for weeks. I can confidently say it was as clean as it was going to get. Most of that top edge of that glass never had any silicone on it anyways.

The tank sat around for at least 3 weeks after the silicone was done waiting for its stand to be finished. And probably a couple more weeks before water was added. Silicone had ample time to cure.

 

[805hd]

The guy I bought the tank off of actually posted it on here for sale originally. Just throwing these out there. You can see how it was originally “braced”.

 

[Backfromthedead]

Yes...its an ill-conceived DIY brace. I have actually committed worse atrocities before learning how the forces involved actually work.

May i ask why are you so averse to keeping only 24" height of water in this tank? It would literally only take removing that overflow (easy), making one even cut across the bottom of it to shorten it(easy) and reinstalling it with silicone (easy). You keep talking about scrapping it...put that plastic frame on and use it for another tank's sump maybe. Or DIY a plywood/hardwood canopy to fit right around the top of the tank and conceal the 6" air gap if youre that concerned about aesthetics. If the seals are still holding water then its not FUBAR yet. Make some mikes hard outta that rotten lemon!

 

[Fishman Dave]

No...no..NO!

Not pressure. Force. The hydrostatic force acting on the side wall of a tank is what determines the thickness of glass needed on all panels of the tank. Water pressure simply describes the weight of water, air, everything above at a given point (bottom of tank for our purposes usually). It is absorbed completely by the bottom glass and for this reason there a force that pushes on the side panels.

Hydrostatic force is calculated in a water tank with a integral equation. For some reason the link is no longer working that explains all this better than i can, but In a tank with water, this is simplified to:

F=1/2(0.036xLxH^2)

F being hydrostatic force
L being the length of the tank
H being the height of the water column

Getting tired of reading "height is all that matters" NO. the length of the tank absolutely matters. This is why a tank like FINWIN is suggesting at 40" long and 33" high may not require the same thickness panels as a tank 80" Long and 33" high.

I'm not doing all the calculations cause 1. I don't know how and 2. I'm an expert half-asser.

We calculated force on the front panel of 72x24 at 746 lbs. earlier in this thread. Every reputable manufacturer in the world makes 6x2x2 tanks out of 1/2" glass. So in my mind 1/2" would work just fine for a tank with a front panel 40x33 and a force of 737 lbs.

Mmmmmm still not sure on this but I think we may be stating the same thing.
The pressure of water (rhoe (which for water is known) xforce of gravity(9.8) x height or depth) (N/m2) is what determines the glass thickness based on acceptable deflection calculations (which is where your tank length comes into it and the modulus of elasticity for glass and it’s tensile strength.
The pressure of water pushing outwards is directly related to the depth of water above that point x the force of gravity. Which is why the calculation of the pressure is still the same one used for a glass tank or a viewing panel under water. But yes the next part of the calculation to work out thickness has to calculate deflection so length that the pressure is acting on matters. It is at this point that instead of using the pressure (N/m2 or N/inch2) you calculate the deflection as though that pressure was a force applied to the centre of the length of the tank glass panel.
So yes it is pressure of the weight of water at depth pushing outwards that you turn into a force applied to the mid point of the front glass panel.

 

[Backfromthedead]

Mmmmmm still not sure on this but I think we may be stating the same thing.
The pressure of water (rhoe (which for water is known) xforce of gravity(9.8) x height or depth) (N/m2) is what determines the glass thickness based on acceptable deflection calculations (which is where your tank length comes into it and the modulus of elasticity for glass and it’s tensile strength.
The pressure of water pushing outwards is directly related to the depth of water above that point x the force of gravity. Which is why the calculation of the pressure is still the same one used for a glass tank or a viewing panel under water. But yes the next part of the calculation to work out thickness has to calculate deflection so length that the pressure is acting on matters. It is at this point that instead of using the pressure (N/m2 or N/inch2) you calculate the deflection as though that pressure was a force applied to the centre of the length of the tank glass panel.
So yes it is pressure of the weight of water at depth pushing outwards that you turn into a force applied to the mid point of the front glass panel.

The pressure is required to find the force and included in that 0.036 simplification above, the force is required to find the deflection(pressure not needed at this point). We may be arguing semantics as so many people everywhere call the force "pressure".

 

[Backfromthedead]

Glass Deflection Calculator - Calculator Academy

Source This Page Share This Page Close Enter the load or pressure, length of the glass panel, modulus of elasticity, and moment of inertia into the

calculator.academy

The P In the formula is Point load, denoted in Newtons or lbs-force, which we both know are not pressure units (kpa, psi, atm) but rather units of force. But hey, even that calculator erroneously says "load or pressure", which is very misleading imo. People will try to put the calculated pressure like you're describing into that formula rather than the calculated force which is what is required.

Yes they are related values. My point is that length of the tank absolutely does matter when calculating glass thickness, not just height.

 

[FINWIN]

No...no..NO!

Not pressure. Force. The hydrostatic force acting on the side wall of a tank is what determines the thickness of glass needed on all panels of the tank. Water pressure simply describes the weight of water, air, everything above at a given point (bottom of tank for our purposes usually). It is absorbed completely by the bottom glass and for this reason there a force that pushes on the side panels.

Hydrostatic force is calculated in a water tank with a integral equation. For some reason the link is no longer working that explains all this better than i can, but In a tank with water, this is simplified to:

F=1/2(0.036xLxH^2)

F being hydrostatic force
L being the length of the tank
H being the height of the water column

Getting tired of reading "height is all that matters" NO. the length of the tank absolutely matters. This is why a tank like FINWIN is suggesting at 40" long and 33" high may not require the same thickness panels as a tank 80" Long and 33" high.

I'm not doing all the calculations cause 1. I don't know how and 2. I'm an expert half-asser.

We calculated force on the front panel of 72x24 at 746 lbs. earlier in this thread. Every reputable manufacturer in the world makes 6x2x2 tanks out of 1/2" glass. So in my mind 1/2" would work just fine for a tank with a front panel 40x33 and a force of 737 lbs.

The bottom is a different story since the height is different. But I don't know all those deflection calculations so if I'm building that tank it's getting a 3/4" bottom and that's that.

FINWIN i must confess when I delivered that stand to your home I had an ulterior motive...I wanted to inspect that big tank . I think you hit it on the head. That beefy aluminum frame both reinforces the entire bottom silicone seam and augments the front panel by encasing the top and bottom of the glass in 2-3" of thick aluminum. In my mind this effectively shortens the water column that is only supported by the glass and adds the strength of that aluminum to the entire height which is a ridiculous bunch more math so lets just say customaquariums has it figured out better than we do, obviously a very strong design when inspecting the tank...I still wanted to get my long straightedge out of the truck and check for deflection though

Ha haa...sneaky

Yeah that frame is no joke. I almost had to break one of the AquaClear 100s to remove and check the impeller! Even now I dread having to move/remove those. I don't know what it's sealed with (maybe concrete, lol) but that frame doesn't flex and doesn't move! The bottom is the same.

Because I was getting an oscar I went with tempered on the front and sides. Wasn't necessary for the printed back and bottom (and I paid attention to posts here about the difference in case of a blowout). I also wanted more gallons on the same footprint. So the original order would have been 3/4" glass all around but when I changed to tempered, it went to 1/2". So a 215 became a 225. The bottom is still 3/4" that wasn't going to change in the specs. When I requested tempered Custom Aquariums said it would be 1/2" no problem.

Turned out to not be a bad decision. My oscar Brick had no problem moving objects up to 5lbs once he got to a foot. I had a large ceramic log cave he slammed/knocked against the walls more than once. Ditto on some 8 inch boulders he would bang against the front and build a fortress wall. So not tempting fate I took that stuff out. Fish was strong asf and I still miss that big goofball.

Coming downstairs to boulders piled against the front glass wasn't something I wanted to see!