RO stands for Reverse Osmosis.
When you swapped the sand beds this could have removed alot of your bacteria that break down both ammonia and nitrite did you keep an of the old bed in there in bags? Also if you dont have much live rock most all of your bacteria will be on the sand.
When you swapped the sand beds this could have removed alot of your bacteria that break down both ammonia and nitrite did you keep an of the old bed in there in bags? Also if you dont have much live rock most all of your bacteria will be on the sand.