When a number doesn't click in your brain

I wanted to share this item with y’all, because we all learn and relearn things daily. I’ve been testing alkalinity like clockwork, but the tank has been running lower than I like. I adjusted the black knob on this controller down slightly, but the number on the screen has pretty much been sitting at 7.5 (pH) for days. I thought that was odd that the number never changed, so I investigated further this afternoon.

What I didn’t REALIZE was that it was measuring 7.5.  (Spoiler alert: I've usually had it around 6.2 to 6.5)

It should have been around 6.5 or somewhat lower all this time (as pictured above). The lower the pH, the more the media melts in my calcium reactor. The melted media outputs higher dKH solution into the tank. By twisting the black knob downward, it sets the melting point lower, but I wasn’t getting the desired results despite adding more CO2 which should drive down the pH in the reactor. With the higher pH (7.5) in the reactor, the media was not melting much, thus the dKH coming out of the reactor wasn't sufficient for the job; the corals in the reef consume alkalinity constantly and that is why the parameter was lower than my preference, as mentioned at the beginning of this entry.  I like my alkalinity measure around 9.5 to 10 dKH.

I’ve been running a calcium reactor so long that I didn’t make the connection, that this number was pretty far off the mark. 7.5 didn’t trigger my brain to think something was amiss, as I was more focused on the dKH of the reef. Of course now that I’ve typed this out and handled the need, I won’t soon forget it. But perhaps a small label printed and affixed on the front of the controller with a general range would be wise to do so I catch errors more quickly.

The solution, by the way, was to clean out a small inline check valve on the reactor itself which had stuck closed with saltcreep, which prevented CO2 from entering the reaction chamber. All better now that is has been cleaned out, and silicone lube applied to the o-rings. I've buffered the tank twice over the past few days so the reef didn’t notice the snafu. And for the next few days, I'll watch the alkalinity closely to make sure it stabilizes where I want it, and avoid an excessive rise in numbers.