Yeah - they dont need much in the line of water changes, but to achieve good growth, I've found water changes essential. Not that they wont grow explosively without the compulsive water changes, just thats my theory on the WC issue. I personally am not big on dosing things because I've found that water changes with good salt keep most levels where they need to be. Some people dose iodine for zoas, however, I'm terrified to add anything that can become so toxic so quickly and lead to huge problems. Plus, I'm cheap and dont want to spring for one, the test kit, and then two the additive.