Curing in the Aquarium aka Cycling your tank
Many people cure their rock in their aquarium. Your rock will shed bits of detritus as it cures which you don't want to get all mingled in your sand. So, it is best if you do not add your sand until your cycle is over or most of the way over. While your rocks are curing in your tank you should not turn on your lights, and you should not have
any fish, snails, hermits, or anything else in there. Be sure to have a few powerheads in there with plenty of flow, and use a turkey baster to blow the detritus off the rocks twice a day during the entire curing/cycling process. Be sure your salinity is 1.025-6 and your temperature is around 78-80 as per usual reef quidelines. When curing in the tank it is best to have your skimmer running right from day one. Check the collection cup regularly as it may fill up rapidly in the first couple weeks.
To monitor the curing (often called cycling the tank) you need to check the levels of ammonia, nitrite, and nitrate. Even if you’ve bought previously cured live rock, you should still follow this process anyway as it is likely there will still be a small cycle. At first, test the water every day for ammonia until the ammonia drops to 0 and stays there for 3 days straight. If the ammonia goes above 2 ppm do a 75-100% waterchange right away to prevent the high ammonia from killing off beneficial life on your live rock, repeat whenever the ammonia goes over 1 ppm (or even better do waterchanges if it goes over 0.5 ppm). Feel free to do as many waterchanges as you want...go ahead and do 50% everyday if you feel so inclined. This will increase the biodiversity on the rocks that survive the cycle.
NOTE- it is a myth that doing waterchanges will slow down the cycle. The reasoning behind that myth is that you are removing nitrifying bacteria in the water column and dumping them down the drain. These are the nitrifying bacteria whose population you are trying to increase as quickly as possible to finish the cycle as quickly as possible. The reason this is a myth is because there is very little nitrifying bacteria in the water column to begin with. The nitrifying bacteria mainly colonize the rocks, sand, and other surfaces. There is a small amount that colonize the water column, but it is not significant enough to slow the cycling process.
After the ammonia drops to 0 you don't need to test for it anymore. You can start testing once or twice a week for nitrite, but you can skip nitrite and just test for nitrate if you want. Nitrite isn't toxic in saltwater aquaria as it is in freshwater aquaria. To clarify:
If testing for nitrite, once nitrite drops to 0 you don't need to test for it anymore either. It may be at 0 when your ammonia gets to 0, or it may take some while yet. Once both the ammonia and the nitrite are at 0 and have been there for a week do a 50-75% waterchange siphoning out as much detritus as you can see including sucking it off the rocks.
If you are not testing for nitrite, wait a week then do a 50-75% waterchange siphoning out as much detritus as you can see including sucking it off the rocks.
In the week that you are waiting to do the large waterchange you can arrange your rocks the way you would like them. Be sure they are secure, and set them on the glass, not on the sand (digging fish will dislodge rocks set on top of sand). Use 2-part aquarium epoxy if you would like. Then add your sand around the rocks. If buying dry sand, rinse it well before adding it to get rid of as many fine silts as possible. If buying “live” bagged sand no rinsing is required. To help ease clouding a bit turn all the pumps and powerheads off while you add the sand, and you can use a mixing bowl or such filled with sand, and lower to the bottom of the aquarium to gently pour it out down there. Once you have all your sand in the tank leave it for an hour, then turn your powerheads and pumps back on . Your tank may remain cloudy for a week or possibly even two. Eventually each grain of sand will get a microscopic film of bacteria around it, and this will weigh the sand down.
Leave your tank running with the sand in it for a week, then test for ammonia, nitrite (if you want), and nitrate. If ammonia and nitrite are both 0 and nitrate is 5 ppm or less, it is time to add a
small clean up crew, and further along you will start to add fish. If nitrate is more than 5 ppm you will have to continue to siphon detritus out to lower the nitrate.
Even further along you may start to add corals. But that is a whole different thread entirely!
