Converting from regular gravel to white sand

You'll need to remove the fish to another place while you change it out. Rinse the sand till the water runs clear and then rinse it some more. With any luck, it will settle soon and the fish won't have to be out very long. I didn't remove my fish when I switched and they all died. I think some of the sand particles got into their gills or something. You may experience a mini-cycle. The best way would be to do maybe 25% swap at a time. I didn't do that (impatient) and I wish I had. Not long after I changed the substrate my filter died (another reason to let the sand settle well before turning your filter back on) and my cycle started all over. Anyway....just me experience.

i would remove all the gravel, as destined_love said rinse the sand thoroughly before adding. You can hang some of the gravel in a nylon stocking or media back in the flow of your discharge for a couple of weeks. you will want to turn off your filters when you first add the sand to let it settle (so particles don't get in the impellar of the ac). hope this helps...haven't actually done it myself.

there should be plenty of bacteria in the filters, but during the moving process make sure that the filter media stays wet. it shoudlnt be a problem in the canister, but you may want to take out the media in the AC200 and put it into the bucet that the fish will be going into.

I just went through the same thing this weekend. I switched out the gravel in my 55g tank to a sand bottom. I bought several rubbermaid roughneck storage totes... they work WONDERS when storing water or anything else heavy. I've found a 14g storage tote to be able to hold well over 120lbs without any worry of leaks or breaking it. Siphon off a good volume of water into a storage container to save for when you re-fill, and depending on how you do it, either put the fish in that water or keep them in a separate container of tank water, prefferably with plastic plants floating in the top so they don't feel so stressed out from the sudden change. Siphon out the rest of the water, suck up all of the muck under the gravel (if any) and scoop out the gravel. Rinse the tank, scoop in your sand, fill it up with tap-water, get it dechlorinated, and get some tank water in there so you can get your heater on. I've placed some pantyhose over the filter frames for my emperor 400 and left my canister set up the way it normally is. I have my intake tubes 2" above the sand. The pantyhose is doing GREAT at getting rid of any residual silt. Sorry for the jumbled response... I'm at work and trying to deal with a whole bunch of things while posting this.

Move the fish to a bucket etc. then fill the tank as desired. The filters have enough BB, it's ok your good to go~ Feed sparingly for next few days~ good luck!