nc_nutcase;3268848; said:
I have no problem with anyone questioning my posts
and Ill be happy to explain why I think what I think
While on one hand this is true, on the other the height of a tank dictates its weight per square inch
and a tank which is only supported by its edges has much less surface area in contact with the stand to distribute this weight
On a tank that is only 1 front to back the glass spans a shorter distance than larger tanks
but on the contrary it uses thinner glass
I won't deny that there is validity to variance in the size of the tank, but in relation to the thickness of glass vs gallonage, the conversation steers back to relative information. It's not something to argue, but something to keep in mind. Tanks are tank and to some degree they are all build against the same formulas.
nc_nutcase;3268848; said:
To simplify it
Styrofoam dents
and if there is additional pressure in one place, such as a raised corner, this will cause additional pressure on that place causing the raised point to dent into the Styrofoam more so than in adjacent areas
The compression rates of foam are very easy to calculate. The rate at which foam compresses is directly proportionate to the weight exerted on the foam. If a tank is higher on one corner, there will be less weight exerted on the foam, thus, less compression of the foam. This in no way supports the tank, but gives the impression of support. The relationship of weight around the other three sides as opposed to the one high corner will show that the compression rate of the foam will not support the high end of the tank to the degree in which you need. I have done the math behind this in another thread. If you like, I will post the link with the calculations or post them in here.
nc_nutcase;3268848; said:
The tank I made an example out of did not leak at the seal
the front pane of glass cracked from the bottom left corner across to the middle of the right side
It sounded like a bomb going off when it did
After inspecting the stand, I found it to be twisted
putting the styro/ply/styro sandwich between the tank and the twisted stand fixed the problem (and was not simply a patch to delay inevitable results)
I used the term leak as a broad term. I have had one leak at the seal, and I have had a 20 burst exactly as yours did. I feel that both of these cases were related to the levelness and the tendency of the silicone to break. The 29 was originally a bit off level when setup at my other house. As soon as I put the tank back up and filled it (level), it burst at the seams.
nc_nutcase;3268848; said:
I would also like to add when we get into specifics on this topic we should clarify that it is very important to ensure the tank is flat on the stand, but the stand/tank being level is not a critical point. A twist in the stand or a raised corner or a bowed stand can cause indifferntial pressure on the tank which will stress the glass and/or seams which can result in either a blow out (broken glass) or a leak in the seal
But if the tank is sitting flat on a stand that is flat
but for whatever reason the tank is not level (perfectly parallel to the earth)
the pressure will be evenly distributed to the stand
Flat is just as, if not more important than level in most cases. I agree with you and hybrid theory on this. And in all cases, you should strive for both, period.
The one fact that I will slightly disagree is the need to have additional shims every three inches. Although I understand the though and believe that it could prevent some issues in the future, there are many example of tanks that have been only support on two side with the length going unsupported. One example would be cinder block stands. These tank are built to withstand this. Is there an inherent risk associated with doing this? Yes, there is. But it is possible to do this. Of course, we would then get back into the relationship of height to weight to glass thickness. We could go on all day. Bottom line, it doesn't hurt and may help, so why not do it?
Example, I shimmed a 55G tank that was high in one corner. I used a shim and left it at that. Theoretically, the tank was then unsupported in the middle and it only sat on the ends. This tank was completely level and I never had any problems. To some degree, it depends on the tank age, and how it was setup before. This example was a brand new tank. If that makes a difference, I'm not sure. There are a lot of factors that can be unknowns.
