for the tank, gravel etc you can use a little bleach and then sit in the sun for a few days then do a few rinses. the bleach is removed by the sunlight. and i know you can do something like that with plants but i've never tried it.
hey all just putting it out there that i will be driving down to wellington in the next few days ( Tuesday or wedensday) for a few days before coming back up again. so if there is any thing you want bought up or down PM me and if it isn't on the way we can sort out a small petrol fee.