SH IV See through water

[A Very Super Market]

No, it doesn't work that way. Just because its connected doesn't mean its all the same. Forget currents, the sheer distance water needs to travel to get fomr the Atlantic to the Pacific means that the two will take milleniums to completelymix. Besides which, currents tend to circulate water only within their respective ocean. The Pacific is clear because there are large swatches of it that are devoid of life. Meanwhile, the Atlantic is swarming with plankton, fish that eat plankton, fish that fish, and decomposing remains of said animals. That'll definitely change the water for ya.