Need help with generating a uniform weak magnetic field

[Howard Bell]

Hi, I'm developing a new bio reactor, which in this instance you can think of as just a perspex fish tank. But have come across an unusual requirement to apply a roughly 0.01T magnetic field across the volume of the tank with mainly water in it. No position in the tank can be less than 0.08T and no position higher than 0.012T

Any ideas how I might go about achieving this at a reasonable cost?

 

[PietKuip]

Helmholtz coils: http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/helmholtz.html

 

[Howard Bell]

Brilliant, just what I needed. Many thanks, my first post and a useful answer straight off the bat, very impressed.