Pacific vs. Atlantic, round 2

Ran into this quote about the 20-centimeter average difference between Pacific and Atlantic water levels:

http://css.sfu.ca/sites/water-web/

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The Pacific ocean is higher than the Atlantic ocean because the Atlantic ocean is warmer, hence saltier, hence more dense, and being so heavy, it is lower. Water flows from the Pacific to the Atlantic in the Panama canal. This was actually an environmental concern when the canal was built and a series of locks prevents too much flora and fauna from going through.

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-- and it surprised me considerably. I thought I had read somewhere that the difference had something to do with the rotation of the Earth: water piling up on the western shelves of continents, or some such. I wouldn't be surprised if that were a silly superstition, but then again I still wouldn't be surprised if it were true, either.

In any case, I didn't like the density explanation very much. If the Atlantic were full of molten lead, it would theoretically be a heck of a lot lower, "being so heavy" -- but that wouldn't prevent the water in the Pacific from flowing right in over the top of it.

It would make sense to me if the difference were due to the Atlantic being warmer and thus evaporating more quickly -- and apparently it is warmer, as the quote above says. Certainly 20 centimeters' difference in height over half a world wouldn't do a whole lot to create a raging current to correct the situation; so maybe the discrepancy is just the equilibrium point between the extra evaporation and the water that comes in from other oceans to replace it. That picture would also account for the Atlantic being saltier, of course -- but this reverses the cause and the effect given in the explanation above!