Frank Cadena said:
It's not the sea/ocean that saps/supresses the Devil Fruit Powers, it's the Kairouseki within the sea that saps them so if you put Luffy in fresh water(no Kairouseki), he'd still drown (cannot swim) but he could use his rubber powers to get himself out. Evidence that it's the Kairouseki and not the sea? In page 70 of volume 26 there is an explanation.
That doesn't refer to the power of the sea being a result of kairouseki at all! It still implies that kairouseki is distilled essence of the sea. Because when it comes in contact with the clouds it forms a sea. They don't even say the kairouseki is in their sea clouds, they say a certain substance reacts with the clouds to form sea and island clouds.
Besides which Luffy before becoming a hammer was a great swimmer. This is mentioned by Shanks' crew. Why would he drown if his powers weren't being sapped?
Let's not forget all the times when they say kairouseki gives off the same energy as the sea, or other such things which I know is said by the people who use kairouseki at least twice. Why would they say that if it is really the kairouseki giving off all of the sea's energy?
Next how is it that the kairouseki effect is transmitted through the water for thousands of meters, but stops at the surface of the water without radiating even a meter further?
Finally why would Kalifa be bathing in a kairouseki bath tub? Because she admits that while bathing her powers are negated over the submerged area. She was in a bath tub, which is presumably not connected to the sea. Why the hell are they making kairouseki bath tubs?