I'm looking to switch my 55 gallon planted tank over to sand from gravel, and while I'm at it I'm looking to add some laterite, and I'm just looking for some suggestions on how to do this. I understand how to switch from sand to gravel, no problems there, but I'm just wondering what would be the best way to get the Laterite in there without clouding my water red. The only way I can think of would be to drain most of the into some big storage containers along with the fish and plants, scoop out the gravel, put down the laterite and the sand on top of it, then refill with the old water, redecorate and put the fish back in. While I don't have a problem going through all that trouble, I'm a little concerned about the fish.
In that tank right now there are:
Apistogramma Borellii x 1
Apistogramma Agassizii x 1
Apistogramma Cacuatoides x 2
Apistogramma Cruzi x 3
Microgeophagus Ramirezi x 4 (2 pair)
Emperor Tetras x 6
(excuse any spelling errors, that's off the top of my head, and i can't for the life of me remember the scientific name for emperor tetras

)
It's a kind of pricey and sensitive collection (apistos are hard to come by where I'm from!), so I was hoping there would be a secret to this that would be easier on them. Another concern I had was with removing the beneficial bacteria in the old gravel. I will be filling a nylon bag with the old stuff and hanging it in the tank for awhile to transfer some bacteria, but how much of a re-cycle should I expect with those kind of stocking levels?
One last question (I promise!). I'm running a rena xp2 on that tank, and I know that sand can ruin impeller filters pretty quick. How long should I leave the filter off for after doing the switch, and/or are there any other precautions I should be taking?
If you have any suggestions at all, please speak up!

Thanks!