Again it would be safest to mark your usual water level on the tank with some tape, prepare a large vessel of treated ph correct water without salt and instruct someone to check the tank periodically while you are away and add the prepared water to the tank until the water level reaches the mark (tape) on the tank....If you add treated freshwater without saline, once added to the dehydrated concentrated saltwater in the tank, it should dilute it and bring the tank water to the proper salinity. Remember salt does not evaporate, only the water it is mixed with...When you return then you will need to do water changes with saltwater to bring down the nitrates....for a week or so of absence this would work, but if you are gone for months it probably will not....Being in the medical profession, the other possibility which comes to mind would be to titrate water into the tank using some similar set up as an Intravenous line, where fluid is titrated slowly from a vessel (using gravity so the vessel must hang somewhere above the top of the tank) down through tubing and dripped into the tank. drip rates can be controlled with a turn screw thing the tubing slides through. In hospitals we can even hook this up to a machine which very precisely regulates the flow (because after all people to the rest of the world are more important than fish.).(hint hint for fish rocket scientists, another useful invention to make affordable for us)You would have to test a system like this before your leaving and be sure it works. Many online places have such set ups available. If you know a nurse or doctor they can easily pick one up for you from hospital supply rooms
I have thought about starting up a nano that would be small enough to take home over winter break, but I think I am going to worry about adjusting to college life at this point, plus I can still visit my tank at home.
