Not sure about sumps, but to avoid some suffering on behalf of the fish, go pick up some microbacter7 or any other bacterial supplement and dose it in your tank. You're definitely not cycled yet and this will help soften the cycle.
"Specially formulated MicroBacter7 rapidly reduces organic waste concentration. Select complex of extremely effective microbes and enzymes break down organic carbon, nitrogen, ammonia, nitrite, nitrate, and phosphate. The result is improved water quality, clarity, and increased dissolved oxygen content for a cleaner, healthier aquarium environment. Use MicroBacter7 to establish biological filtration in new aquarium setups and to enhance the rate of nitrification, de-nitrification, and organic waste degradation. For all marine and freshwater aquariums. 500 mL treats up to 5,000 gallons."
Chances are your LFS (which you should probably steer clear of due to the initial advice) will have this or something along the lines of it.
