hatching zebra nerite snails

Well I thought I'd come and tell you all I'm having a go at hatching some zebra nerite snail eggs.

Whilst I had my main tank under treatment my 2 zebra snails were in my little 30 litre tank and whilst in there they covered it in eggs! I've wanted to have a go at hatching them for a while but never really had the opportunity.

Currently I have one of my two 30 litres running due to the baby mystery fry. This tank is seperated into two sections with a glass pane siliconed in. The baby is alone on one side with a heater and sponge filter and I put the snails in the other section with my mini internal filter as I was worried the sponge filter wouldn't be capable of supporting them (I've found in the past that these snails can create rather of lot of ammonia!)

The snails are now back in the main tank and so I have a half empty tank with about 20 eggs. I've been down to my lfs to find out about marine salt water as all my research about hatching these eggs suggested this was the best way to go about it.
I know nothing about marine salt water! ... what I know about marine set ups you could write on a postage stamp so I'm a fish out of water - if you pardon the pun lol

The lfs gave me a lidded bucket with about 10 litres of marine salt water in it for £2. I can handle losing £2 if this doesn't work!

I came home filled a bucket with the water that had been in the tank and added the stuff that the eggs are stuck to - they'd layed them on the thermometer, the filter bracket and one of the suction cups off the heater! Common sense said to keep the eggs wet so I left those in a bucket while I drained the rest of the water and replaced it with the salt water. I then added everything back that was covered in eggs. I've added a piece of bogwood as research suggested that this will provide food for the hatching snails to begin with - I'm guessing the slime coat is the 'food'

I can't seem to find any info on how long they will take to hatch. The best info seems to be to use marine water due to the minerals that the shells need to begin with. There's also some info to say they need the water changing every 3-4 days. I've no idea at what stage you start reducing the salt water for fresh so that will have to be down to my common sense.

If there's anyone on here that's already tried and succeeded with this then any advice is greatly accepted! In the meantime I'll keep you all posted