You could try keeping the jug intact and inverting it in the sump using a stand of some sort, just like the way a water cooler is set up. The water in the jug will not flow out of a sealed container unless the air can get under the edge of the opening and up into the jug. It's the same basic principle of putting a glass underwater in your sink, fillit with water, turn it upside down and lift it out slowly. It will not empty until the glass is completely above the water level in the sink. However, I don't know if this sort of setup would be possible in the sump, as it may leech salinity into the jug, thereby reducing your salinity in the tank, but how much it would affect it would also be debatable. I guess if you had a sump large enough to make a chamber at the end on the other side of your return so that there was no discernable water movement that would allow the water in the jug to circulate with the water in the sump, it would drastically reduce the amount of leeching it would produce, and as the water in the sump fell below the edge of the jug, the jug would drain water into the sump to raise the level above the edge of the jug. If I were running a sump on any of my tanks, I would try this, but as I don't, if there is a courageous soul out there willing to test this, please let me know how it turns out. It may be a much cheaper method that the expensive automatic drips they sell, although it would certainly be more maintenance than their costly counterparts.
