[untamed]

For some time now, I've been challenged to keep the tank's alkalinity up. Each time I noticed the alk falling, I would increase the flow to the reactor a bit. Eventually, I hit the max output of my pump (117ml/min)...and began to think..."this isn't right!".

My Ca/Alk usage shouldn't be extremely high...yet. My corals aren't large enough and there are lots of other tanks with much more coral that haven't max'd their Ca reactor.

One popular theory was that I was flowing so much water through the reactor that I was not allowing time for the media to dissolve. I began to measure the alk output of the reactor. My first reading was 13! (I was hearing other people had readings over 20).

So I began to turn the reactor flow down, and measure the output every day. I got right down to 65ml/minute and the alk had only increased to 14. No...this wasn't a flow problem.

So I started working on the pH. I dropped the pH of the reactor from 6.6 to 6.55...no change. I dropped the pH to 6.50, no change....

Then, I recalibrated my pH probe and dropped the reactor to 6.45. Alkalinity jumped to 24! As always, because I had done two things I don't know which solved the problem. I strongly suspect that the probe had become inaccurate.

Anyway...the lesson learned is.."Calibrate your reactor pH probe frequently".