Very loud. I had 2 installed on a peninsula in my living room. very intrusive both visually and audibly. for less $$$ I would go with Maxspect Gyre.
I run both the QD and the ES version on my tank and the QD is noticeably much more quiet, but it is not unbearable. This pump is so versatile it will probably be the last type of pump I buy, but certainly not the last Vortech.
on January 15, 2017
Great product but compared to QD version of the same powerhead this gets only 4 stars due to noise. QD is silent.