Hertz

Have you looked at the datasheet for the opto-isolator IGBT/MOSFET date driver IC you're using?

The output goes the the MOSFET's gate, to avoid high frequency oscillation there should be a low value resistor between it and the gate.

If Styx doesn't return in a couple of days I'll post a schematic demonstaring how to drive one MOSFET using the DC-DC converter and the optoisolated gate driver IC.

try this

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Thanks alot guys youv'e been a real help

Hopefully ive got this right this time, I think ive understood what youve been saying

just a couple of questions, can 2 FET's be driven from 1 driver to save on components and board space? and I want to protect the pumps from any possible damage and was thinking of puttting a fuse in, would i put this after the board on the 240VAC out?

Also I cant find the MCPL-3140-000E in the UK suppliers that i use would this one be a suitable replacement? https://www.electro-tech-online.com/custompdfs/2007/07/0900766b80028805.pdf

That ought to do the job, although it isn't as good to the IC origionally suggested, it's more than good enough for this application.