Powerhead problem


Reefer Madness
I just picked up my tank and I have a problem. I had purchased 4 Hydor 750 Evolution powerheads as the tank was being built now my problem is that my tank is built with 1/2 inch glass and the magnets for the powerheads are supposed to be rated for up to 15mm thickness, my tank is 12mm thick and the magnetic hold is very weak I am worried that if I am not home and the powerhead comes loose and falls into a bad spot it could really mess up the tank if gone unnoticed for awhile. I have emailed Hydor but I do not expect much help from them at this point.

I realize that 1/2 inch is pretty thick for my tank (it's only 70 gallons) but a guy I work with builds them for LFS's in the city where I live and that is what he had for glass stock. I had done my homework and the equipment I had already purchased should work. I cannot afford the Vortech MP40's as much as I would like even the Tunze's are 250-300 bucks a piece. I am in central Canada and marine aquarium equipment is insanely priced here. So here lies the question does anybody have an idea of better securing the powerheads to the tank wall. It looks like I might have to glue them to the tank, I do not want to do this if at all possible. I was told by the online store that I bought the powerheads from (www.jlaquatics.com) to consider using Orca underwater glue. Thanx for any input.
you should have a problem really. Remember that the magnet is there as a security measure. The pump can stay on with that suction cup all by itself. That being said, yea maybe some glue. Use fish tank safe silicone, At least that will come of easily and will be clear so you can't see it.
You cant apply the silicone under water and the glue will ruin the glass. You are going to want to move them around because how you have rocks and corals will partly determine where the flow needs to go. And they will need to be taken out and cleaned every now and then. You can secure the cords against the tank with some tap on the outside and that will help keep the powerheads in place. I promise you that you will really regret permanently securing the powerheads.
LF, can you not put silicone on glass? I had always heard you could just scrape it off with a razor blade. Sorry should have clarified that the glass would need to be dry.
silicone even when scraped on the glass will leave a film where you had used it.. Found this out the hard way a few years back,, (Never could quite get it all off).. like Hannah said some tape on the outside will work fine...
Suction cup does not hold well on its own, I would rather try to silicone it instead of gluing it. The area of the tank needs to be dry. I do not know how I am going to do this once I have water in the tank and I am going to have to fine tune placements of the powerheads. I really wish manufacturers of equipment would be true to their word for their products, I've done the research and these powerheads should easily hold properly according to their own product specs.

Thanx for the input.
No, the problem is that you cannot use the silicone while you have water in the tank, and it has to cure for several days before its safe to be exposed to the water.

Personally, i would just buy a new set of magnets (they have very cheap, powerful ones) and attach it to the powerhead you have.
With as often as I have had to take powerheads out of the tank for maintenance and such, I wouldn't EVER want to glue them to the actual tank.

What about exchanging the ones you have for ones with stronger magnets?
I have thought about changing the magnets does anyone know if the magnets have to be treated or coated in any way for a saltwater environment.

Anybody have an idea where to get stronger magnets?

Thanx again for your input.
Buying new magnets is a good idea -- you only need a new magnet for the halves that go on the outside of the tank, so it doesn't matter if they are treated or coated.