Dear all,

I am silent reader of mailing list and also not expert in electronics.But on this subject every one is making the solution comlex discussing ac/dc electrolisys and cable length. Why not put simple reed switches in the long 10/12mm glass or pvc tube at defferent levels and put a round floating magnet (like the break fuid level switch in cars) and connect any voltage i.e. 12 or 24 and get as long cable you need.

hope this will do. forgive me if any thing is wrong as I am not and expert like you all here

Regards......Manjeet