Snails and iron toxicity

[Dave Wilson <rwilson at octa4_net.au>]

I have a huge amount of water with aquarium plants and am not allowed 
to put clown loaches in it, nor is it practical to physically remove 
the snails by hand, it helps but they always come back.   Can anybody 
help with a rumour that snails can be killed by raising the level of 
iron in the water, an action that will not hurt the plants too much. 
If this is true how much iron in parts per million would you need to 
add to the water to kill off the troublesome snails.   My snail 
problem is a local Australian native snail that loves to eat all 
plants except hydrilla.

Any ideas appreciated.

Cheers
Dave Wilson
Howard Springs, NT, Australia