i was trying to find the post where i had done this before but couldnt find it - heres what i did anyway
* move as much water into buckets and chilly bins as possible * move the heater and fish in the chilly bin
* pull out the stones with a dustpan * put in the washed sand
* replace the water from other buckets and make sure the water is back up to normal temp * move the fish back to the tank and top up the water as required
i turned my canister off until the water was back up to the top, about 1.5 - 2 hours, i didnt bother bagging just in the chillybin with as much water as possible.
seems to be the least stressful way for the fish bar catching them to begin with
Thanks heaps