Will getting the larger mag float crack/damage my tank?

I have a 45G Freshwater tank. The glass in my tank is around 0.5 inches (5mm) thick. Today I wanted to buy a Mag Float Large + and the guy at the LFS said that it would damage/crack the glass because on the package it says "for aquarium surfaces up to 3/4" or 20mm thick." He recommended that I get the small or medium instead. I personally wanted the bigger one in case I upgrade and get a larger tank in the future. Do any of you know if getting the larger mag float will indeed crack/damage my tank? or is this guy just an idiot?

Thanks in advance

 

It probably won't, but there is a very small chance it could.. that's why they advertise it like that. In the end it is your money though so spend it how you think you should.

 

It probably won't, but there is a very small chance it could.. that's why they advertise it like that. In the end it is your money though so spend it how you think you should.

I thought they only advertise that cuz of the size of the pad, as it would be a pain in the to try and scrub a big tank with a small magnet?

 

Nah, you're good

I don't see how it could crack the glass unless you (for whatever reason) put a ton of force on it

 

If the glass is .5" then that would convert over to 12.5mm, if it 5mm glass it just may break from water pressure.

 

They say up to 20mm thick just because if the glass is thicker the magnetic force between the two halves will be so weak it will keep falling off while you use it. Not because anything under 20mm will break the glass. You'll be fine.

 

If the glass is .5" then that would convert over to 12.5mm, if it 5mm glass it just may break from water pressure.

Water pressure?
We aren't sending it 1000 leagues under the sea
I don't see how water pressure from a home aquarium would break anything

 

5 mm is only 1/4 inch glass, it just seems a little thin for a 45 gallon.

 

Water pressure?
We aren't sending it 1000 leagues under the sea
I don't see how water pressure from a home aquarium would break anything

Say you have a 2'X4' pane of glass on your fish tank. That will have an average pressure of about .4PSI on it(about .85 at the bottom, 0 at the top) That's 460 lbs of force. That's basically the weight of a couple fat people.

 

Say you have a 2'X4' pane of glass on your fish tank. That will have an average pressure of about .4PSI on it(about .85 at the bottom, 0 at the top) That's 460 lbs of force. That's basically the weight of a couple fat people.

Thanks, I wasn't really feeling like looking that stuff up even though I'm good with dive physics.