There has been alot of talk on the forum lately about powerhead holder since suction cups have such a limited life if any at all. I was doing some tank maintenance and decided to try and make some out of acrylic. they actually turned out SLICK .
just cut the acrylic wide enough to fit the PH holder and approx 8-12 inches depending how low you want it in the tank. took a torch and heated the acrylic till it was workable and just bent a "hook" to go over the tank. I then drilled holes in the acrylic and fastened the holder to the acrylic with some plastic binding screws.
They work very very nice and the acrylic is very nice and doesnt stick out.