[minsc_tdp]

Ok, at this point I might be revealing my position but I must.

When the first chamber fills, the seal still has 999 LBs of strength holding back the water. It's not enough to keep it out completely, thus the slow leak. Once the first chamber fills, how does that change the strength properties of the seal? It doesn't. It still holds back the water above it with 999 LBs of strength, so the only pressure pushing down on seal 2 is the miniscule weight of the water in chamber 1, which is not enough to put any flow of water past seal 2. So, based on that logic, chambers 2 and 3 will never flood.

If that's wrong, please explain how the pressure on the first seal is only enough to push through a very small flow, yet once it is filled with water, that small amount of flow leaking through somehow magically becomes a full 1000 LBs of pressure on the second seal. I can't see how that is the case.

In essence, the second answer is theorizing that the water pressure will never equalize since the first seal is holding, although weaker than the pressure on it by 1 LB, but it is still holding. Granted, if the seal blew and there was an open flow between the ocean and the first seal, the pressure on the 2nd would be 1000 LBs. But it hasn't blown, and won't.

Not to complicate things further, but in fact, I believe once the first chamber fills, the presence of water in the first chamber will create additional outward strength assisting the first seal, easily keeping any more water from entering, so the outer water pressure in fact would have zero effect on the 2nd seal. The only pressure on it would be the weight of the water in the first chamber, which (as defined) is miniscule and nowhere near 999 LBs required to cause the 2nd seal to leak.

I realize that the size of the leak might actually be an important factor here. In our arguments, he stated it didn't matter if it was pinhole sized or not. I think the amount of pressure that enters the chamber from the outside would probably depend on the size of the leak. For this case though, assume it is pinhole sized resulting in a slow drip.