[quote author=xinumaster link=topic=2609.msg39333#msg39333 date=1207009967] Sulfur will lower the pH. So, water coming out of the effluent will have a pH of 6.5 or lower. You can hook up another chamber full of aragonite media to bring up the pH and at the same time increase ur calcium level. [/quote] Do you need to do anything to the water before it goes in? Or does the sulfur simply lower the pH? Because if memory serves this is around the pH you need for a calcium reactor to dissolve the media isn't it? Unless I'm missing something here seems like you could rig the effluent to go straight to a calcium reactor and not have to use CO2... of course this is assuming that flow rates would be the same. Edit: Nevermind, just saw an article that shows there'd not be much production of calcium.