Ok, when i made the change, about 2 months ago, this is what i did:
1. i purchased a whole crapload of 5 gallon plastic buckets (this should be equal to at least 2X the amount of water your tank can hold). Half of the buckets will be to hold your current water, and the other half will be filled with new water. Of the buckets with new water, about 1/2 of that will hold your LR (this can technically be tap water (to save money), as only the LR is going in it for a while, and this water will not be introduced to the tank), and the rest will be to fill your tank. (like a water change)
2. I began emptying the water in the tank into half of those buckets
3. I prepared new saltwater in the rest of the buckets
4. After removing allmost all of the water from the tank, i quickly put the LR into the newly prepared saltwater (so as to save all of the old water from the tank. When you do this, the water becomes pretty dirty from everything coming off of the LR)
5. I then removed the fish, and put them in a separate bucket (or 2, depending on how many fish you have) with a few pieces of LR. I hooked up a heater, an air pump, and the light to this bucket.
6. Next, i began the tedious task of removing the rest of the water, and substrate from my tank.
7. After cleaning out the tank (with hot water only) I poured the old water back in the tank with 6" open at the top (room for sand, LR, etc.)
8. Put the LR back in the tank (do this before the sand, so the LR is on the glass bottom of the tank. This way, it is the most stable!)
9. Put the sand in the tank (wet the sand with saltwater in a bucket before you do this, to eliminate some of the cloudiness)
10. I left it like this overnight (with the fish in the bucket still) to give time for the sand to settle (i didn't want the fish in the tank with pieces of sand floating everywhere)
11. In the morning, most of the cloudiness was gone, so i added the fish back to the tank.
Didn't see any spike in anything, and now my tank is sooo much cleaner.
Hope this answers your question. I'd do it all at once. On a saturday, or your day off, so you have the time for it! It'll be a pain in the you-know-what, but it's definately worth it.
Jenn
