Yes it is indeed SATA powered. I have tried using other various SATA power connections across various cables and the same noises occur. When I disconnect the power to the pump the noise ceases(due to the pump not spinning).
Under the same lighting conditions, the pump seems to spin at a slower speed when operating under normal conditions (24 pin ATX), than when I use that loop testing cable.
EDIT: Pump was spinning faster with 24pin ATX(2500 RPM), Slower speed(normal 1400?) with the tester.