On a very basic level, some reefers kind of understand the interplay of carbon dioxide, carbonate, carbonic acid. However we’re not quite as sure that saltwater aquarists really understand how these chemicals affect pH and alkalinity, and especially how it relates to the growth rates of corals in our home aquariums.
Like so many aspects of keeping marine aquariums, coral growers can wax poetically about the esoteric needs our corals have for exotic trace elements, uncommon amino acids and how they react to specific wavelengths of LED light – but when it comes to the fundamentals of aquarium chemistry like salinity, pH, and temperature, not so much. Even if you think you really understand the carbonate chemistry of saltwater and how it dictates the growth rates of our corals, you owe it to yourself to watch at least some of this new program from NOVA.
Entitled ‘Lethal Seas’, this documentary raises the alarm about the rate of ocean acidification in our oceans, and how this is already impacting marine life. The program explores how some oyster farmers have basically started adding kalkwasser to incoming seawater in order to restore the carbonate hardness for their baby oysters.
Meanwhile in Papua New Guinea coral reef ecologist Dr. Katharina Fabricius, studies natural seeps of carbon dioxide bubbling up in certain coral reefer of Milne Bay, and the acidifying effect of having soda water forming near corals. Dr. Fabricius is better known to reefers as the author of Soft Corals and Sea Fans, but in this video segment we can see the direct link between acidic water and negative impacts on fish behavior, and negative effects on coral growth.
While we coral growers do pay some attention to keeping our pH high through a balanced and steady concentration of carbonate hardness we call alkalinity, we really should be thinking of CO2 as a pollutant in our aquariums, and minimizing this gas from our aquarium water in order to promote better and faster coral growth. Several parts of this NOVA Lethal Seas segment really explain why and how CO2 impacts the growth of basically anything with “shell”, including corals, so do yourself a favor as an aquarist and give your reefer brain a little lesson and refresher on the carbonate chemistry of seawater.