I should be moving in the new couple of weeks, and wondered if it would be ok bagging each species in a bag, and putting all the bags into a coolbox to retain the warmth until I get the tanks moved and set up again.

With my main tank I am going to change the substrate when I get the other side also, will it be ok adding the fish straight back in when the water's in, or is it best to let the tank settle for like 15mins first?

I was aiming to find a container to keep most of the current water, and just loose 25% and fill with water the other end, also will the filter media need to be kept submerged in water, or is it ok in an airtight bag?

All the fish in bags and in the cool box (or warm box more appropriatly) will be fine. If you can retain some of the old water that'll be usefull but I wouldnt worry too much if you cant just keep the media again in a plastic bag filled with old tank water.

i'm gonna try and get one of those camping water containers to retain at least 50% of the water, and was gonna bin at least 25% like with a weekly water change
so that's fine....woop woop!

will they be alright do you think for the extra 10-15 mins while i re-set up the tank?

Dont see why not, had mine in buckets for like 40 mins or so (granted it was filterd) with absolutly no adverse effects.

you will be fine for such a short period, i have had emergencies where there has been tank failures and have had fish in containers for 3-4 hours no problems at all

yeah remember when fish are shipped in to the country they're often bagged up for a day or so. a couple of hrs will be fine

that's true and they'll be warm , so do i leave the filter media submerged, maybe in a tupperware tub of tank water or something?

yup, in a tupperware or a fishy bag, just make sure there's plenty of air in there and that it's water tight. if possible give it a shake up every couple of hrs, this gets oxygen into the water to keep the bacteria alive.

When I moved with a 300L tank, I was only able to keep 40L in a fermenting bin. The added water was treated with aquasafe. That was a year ago and all fish were fine. I guess the more water you can keep, the better though.

there's no need to keep any water. i always say start with new actuallly. means you'll have a ncie low nitrate reading on the tank, clean water should help the fish to acclimitise.

only exception is if for example your fish are v sensitive to pH and the new house has a significantly different pH to yours

cheers guys this is great, i'll probably go with 50% to keep to make it easier on me for carrying, etc.
just gotta find out what i'll need to buy fish wise, and get it in the next week or so wooo