Tank restarting question

youclowntoomuch · Jan 9, 2025

If my tank is already cycled and I remove all of the old sand and live rock and replace it with live sand and dry rock will I be completely restarting the cycle or will I have a jumpstart since I have bio balls in the aio chambers?

Fish Fan · Jan 9, 2025

You'll have a jumpstart because of your bioballs, but you'll need time to seed the new rock and sand. You really want the rock and sand to be the main biofilter in your tank, not your bioballs, which are a good backup or to quick cycle an emergency tank.

Why do you want to remove cycled rock and sand?

JayM · Jan 9, 2025

Most of your biological filtration is in/on substrate and rocks, so you're going to lose a significant amount by removing everything in the display. How much gets added back with "live" sand depends entirely on the type of sand you're using.

Mr. Mojo Rising · Jan 9, 2025

It will help more if you can put some of your old rocks into the tank for a few weeks, until the new rocks get populated.

Dan_P · Jan 9, 2025

youclowntoomuch said:
If my tank is already cycled and I remove all of the old sand and live rock and replace it with live sand and dry rock will I be completely restarting the cycle or will I have a jumpstart since I have bio balls in the aio chambers?

Easy enough to test. Go ahead and make the changes. Then add a small amount of ammonium chloride, maybe to a total ammonia of 0.2 ppm, and observe how quickly it disappears. It won’t last many hours if you have a large population of nitrifying bacteria. If it takes 24 hours, consider letting the system recover. If fish and coral are involved, maybe more thought is needed about this test.

youclowntoomuch · Jan 9, 2025

Dan_P said:
Easy enough to test. Go ahead and make the changes. Then add a small amount of ammonium chloride, maybe to a total ammonia of 0.2 ppm, and observe how quickly it disappears. It won’t last many hours if you have a large population of nitrifying bacteria. If it takes 24 hours, consider letting the system recover. If fish and coral are involved, maybe more thought is needed about this test.

My fish are safe in the qt tank for now