I have a few of the power head holders from algae free and they are stronger magnets then they put in there cleaning magnets.
I've has SW
tanks now for 6 years and hated suction cups, seeing that you have to replace then every few years and they fall off all the time.
whats rough is when algae free came out with the holders they were only 14 dollars for the sure grip 50, i bought 6, then i went back and they were up to 25 dollars a little pricey.
I know algae frees cleaning magnets are weak, but other companys might be stronger, depending on the size of the ph you might want to be careful.