Managing water quality is by far the most important aspect of maintaining closed aquaculture systems, as the buildup of too many nutrients can negatively affect both the health of organisms and overall stability of the system. Chaetomorpha brachygona is one of the most widely used algae for natural nutrient export from marine recirculating aquaculture systems (RAS). Despite this, its effectiveness in nutrient export and potential for introducing harmful periphytic organisms (i.e. hitchhikers) is not well documented. Untreated C. brachygona often hosts periphytic, or “hitch-hiking” nuisance organisms such as algae, worms, snails, amphipods, and microbes that could have a detrimental effect on an otherwise healthy system. This project will: (1) evaluate the effectiveness of different prophylactic treatments: (i) reverse osmosis water, (ii) commercial coral treatment (Koral MD Pro), and (iii) iodine solution and (2) explore the post-treatment impacts on C. brachygona: (i) survival and growth, and (ii) efficacy of reducing nitrogenous waste (i.e ammonia, nitrite, and nitrate) in the College of the Florida Keys (CFK) Southernmost Marine Aquaculture Research & Training (SMART) Center black grouper (Mycteroperca bonaci) RAS.