My yearly reef crisis is in full swing...

[wenwillwego]

You mentioned that you performed a FWD with RODI at the "same pH and temp" of the tank. How did you go about adjusting the pH of the RODI to match the tank's pH (i.e., what did you add - RODI has pretty much zero buffering capacity )?

Just baking soda.

 

[zenom]

Are you running anything like GFO/GAC etc?

NOTE I see you are running carbon, so scratch the one thought to run it for chemical warfare. I have seen things "too clean".

Do you dose? If so how much? Any weird dosing happen lately that could cause a spike in parameters.

Only asking because I had a kalk spike one time on accident that caused similar issues.