What killed corals?

[DiZASTiX]

High nitrate and extremely low phosphate killed and kills your corals.

The cause why nitrate seemed to skyrocket after organic carbon dosing is: All nitrate test kits are also sensitive to nitrite, in fact much more sensitive to nitrite than to nitrate. Finally all nitrate test kits only measure nitrite after reduction of nitrate to nitrite. And that is what happened. Your organic carbon dosing reduced nitrate to ammonium, N2 and nitrite. What seems to skyrocket your nitrate concentration is in fact nitrite. Make a test for nitrite.

I hope this helps. If you have any more information on what you described, I'm fascinated. In a nutshell, I don't have nitrates, but instead, a lot of nitrites. It's an error?

 

[Hans-Werner]

You may have some nitrate left but what you describe above is impossible, that nitrate rises after organic carbon dosing. It´s an artifact caused by the nitrate test method. Most likely your nitrate (and also the sum nitrate + nitrite) has decreased but the rise in nitrite completely hides the decrease when testing for nitrate.

 

[DiZASTiX]

You may have some nitrate left but what you describe above is impossible, that nitrate rises after organic carbon dosing. It´s an artifact caused by the nitrate test method. Most likely your nitrate (and also the sum nitrate + nitrite) has decreased but the rise in nitrite completely hides the decrease when testing for nitrate.

Is it impossible even if there has been a mini-cycle arising from a large die-off?
However, what you mentioned came true: the nitrite just now dropped to 0.5 ppm, and the nitrate, 20 ppm!! Brilliant @Hans-Werner !!

 

[Hans-Werner]

If there would be a mini-cycle from a die-off I wouldn't expect that nitrate appears quickly. Nitrate is a kind of end and waste product that only appears when algae and bacteria are saturated with ammonium and there is still ammonium left. I would expect a lot of other things to happen after a die-off before nitrate appears.

 

[DiZASTiX]

@Hans-Werner , you know your ****. I applaud you. Thank you.

 

[futureinterest]

You may have some nitrate left but what you describe above is impossible, that nitrate rises after organic carbon dosing. It´s an artifact caused by the nitrate test method. Most likely your nitrate (and also the sum nitrate + nitrite) has decreased but the rise in nitrite completely hides the decrease when testing for nitrate.

This makes a lot of sense. Nice.

 

[Hans-Werner]

Thank you!:)

 

[vetteguy53081]

Chemistry was your enemy. If you are doing regular water changes, less need to add ALK, etc and enjoy your tank rather than treat it. If using auto-doser, lower the distribution a tad to prevent overdosing probabilities