Sulfur Reactor: Just how much SO4?


New member
My tank is getting older and the inevitable increase in Nitrates is slowly creeping up on me where now they are detectable at 1 mg/L and the growth in nuisance algae is apparent. Deep sand bed is out of the question at this point, and I already do large water changes, and have macro algae growing as well, so I'd like to try a Sulfur Reactor as it seems to be the "cleanest" from a chemical reaction standpoint with a known honest equation:

2 H2O + 5 S + 6 NO3- → 3 N2 + 5 SO42- + 4 H+

(taken from Randy's article Nitrate in the Reef Aquarium)


If I have 3000L of water and 1 mg/l of NO3 how much SO42- will I produce and will it be a problem?

As always thanks to any and all who offer help!



Premium Member
The sulphate production isn't an issue if you're doing regular water changes. If you were going years between changes, it might be an issue.


New member


ReefKeeping Mag staff
Premium Member
Water changes should keep the sufate/ chloride ratio close to natural levels. If you are using calcium chloride for calcium supplemetation and or magnesium chloride it should be even less of a concern and might actually help balance those off a bit.. Fyi: in seawater Chloride is 19,000 ppm and Sulfate 2,700ppm. It would take a long time without water changes to have any significant change.