As long as you have decent surface agitation, you don't need to use the deflectors. They are handy for directing the current where you want it though. If you start to get some cyano
on the sandbed, you can angle some current down towards it...cyano
doesn't like flow much. There is no problem with having the PHs mounted up high. MJ1200 generate enough current to move all the water around in a 75g no matter what level they are. The suction cups, although they are some of the better ones available, will eventually harden and start turning loose. You wouldn't believe what a mess an MJ1200 will make when it falls into the sandbed and runs all night! I'd stick with the clips for that reason if for no other.