Just to be clear... we're not talking about a live shrimp. Use a dead cocktail shrimp from the grocery store to cycle the tank. "Cycling" has nothing to do with the water, but the process of building up bacteria to convert ammonia to nitrates. As the shrimp decomposes, it gives you that source of ammonia. Only thing I'd test during the cycle is ammonia, nitrite, and nitrates... in order to watch the progression of the cycle. Salinity and alkalinity don't matter at this point, and your pH will swing all over the place during a cycle.
So you've just got water and sand in the tank? Are you planning on adding rock in the future? If you are, it might be best to add the rock now. If you add it later, and the rock is not fully cured, you'll experience another cycle in the tank as the stuff that has died off on the rock decomposes. If there are fish in the tank, you risk putting them through the cycle.
