Cincinnati Zoo is Testing the Waters

Posted May 23, 2016

New hippo exhibit is 70,000 gallons closer to being ready for hippos!

Cincinnati, OH (May 20, 2016) The pool is now full in the Cincinnati Zoo & Botanical Garden’s new Hippo Cove exhibit, but that doesn’t make it hippo ready! Before the Zoo’s new hippo pair take their first plunge in the water, most of which comes from stormwater tanks under the lion exhibit, it has to be just right.

VIDEO: Time lapse of hippo pool filling.

Henry photo courtesy of Dickerson Park Zoo
Henry photo courtesy of Dickerson Park Zoo

To make sure that Henry, a hippo that’s so beloved at Dickerson Park Zoo that he’s getting a two-day-long going away party, and his mate have water fit for a hippo, the Zoo hired a water expert. Rebecca Sprague, the Zoo’s new water quality specialist, is ready to get her hands wet. In addition to performing daily water tests, Sprague will work with others on the Zoo’s life support system team to monitor the exhibit’s sophisticated filtration system, engineered to process the 50 pounds of waste that the hippo pair will produce each day, and oversee the volunteer divers who will be cleaning the tank as needed.

“I’ll be testing the water to make sure the chemistry profile is where it should be for hippos and the fish that will share the tank. I’ve introduced beneficial bacteria that will remove organic compounds that can be detrimental to animals that spend the majority of their time in the water,” said Sprague. “It takes a few weeks for the bacteria to grow and for undesirable elements to be extracted from the water.”

To give the filtration system a realistic test, the pool is going to have to contain more than just water. “We will introduce material that’s similar in volume and composition to hippo waste to make sure it flows through the system properly,” said Mark Fisher, Vice President of Facilities and Planning at the Cincinnati Zoo.


The super-filtered water will allow visitors to get a clear, nose-to-nostril view of the Zoo’s two Nile hippos from the exhibit’s underwater viewing area. Hippo Cove, scheduled to open in late July, will also feature a scenic overlook where visitors can admire the full girth of 34-year-old Henry and the 17-year-old female that the Zoo hopes will float his boat. The pair have received a breeding recommendation from the Association of Zoos and Aquariums (AZA) Species Survival Plan (SSP). Breeding plans work to improve the genetic diversity of managed animal populations. If all goes well, baby hippos could be in the Zoo’s future.

Nile hippos, also known as river horses, are vegetarians and weigh about 5,000 pounds (that’s a lot of fruits and veggies). In spite of their enormous size, they can run as fast as a human and can be aggressive and dangerous. Don’t worry, seven plies of ½” laminated glass built to withstand 4500psi of water pressure and the impact of a Hippo going 10 mph will be between visitors and hippos!

As with all Cincinnati Zoo projects, the hippo exhibit is being built to Leadership in Energy & Environmental Design (LEED) standards, pursuing Gold certification. To help us achieve that goal, water used in the hippo pool will be 100% rainwater. Wise water management has helped the Zoo save 1 billion gallons of water since 2005.