16 1/2 inches to the top of the pump and 18 inches at the top of the line that connects to the bulkhead on the lid of the bucket. You need to have a little extra room so you can open the bucket to add the water. My cage stand is about 23 1/2 inches high on the inside, and I can tilt the lid up to add water.
I've never used the Aquazamp phone number, I always contacted Kevin by pm (here) or email. I do know that he had some recent health issues which may cause some delays in his responses.