Had a close call yesterday with Ca dosing

[Reef Pilot]

I adjust my Ca dosing once in a while with my Apex. I dose Ca during the day, and Alk at night. So yesterday, wanted to add an hour to my dosing, changing the stop time from 12 noon to 1 pm. I changed the Apex Outlet coding from 12 to 01 (for 1 PM).

Well, about 9 PM last evening, was looking at my sump, and noticed a drip happening from the Ca dosing tube, and the Ca doser is running. WTF, I thought!! Then I remembered that my Apex time is referenced by the 24 hour clock, and I should have set the end time to 13. Dummy me...., I change this setting about once or twice a month, and this time I still forgot about the 24 hour time clock!!

My fear then was that I over dosed my tank with Ca. The doser ran for 10 hours vs 2 hours normally. So I tested Ca, and to my surprise it was only at 420. And it was at 400 that same morning, before I changed the Apex. I also tested my Alk, and it stayed the same, at 8. So that was a surprise. I expected my Ca to be way up, and possibly my Alk to have dropped. I checked it again this morning, and it is still the same.

So looks like nothing bad happened. Does my tank, with all the live rock and corals, have a large buffering capacity, which prevented a larger swing in these parameters?

I think I will also change my Apex start/end times to be in the afternoon, so I don't make this mistake again.

[Delphinus]

Is it possible your Ca was lower than you thought it was beforehand?

I'd be more worried about an Alk overdose than a Ca overdose though. If you think of it that's only about 4-5 days worth of Ca dosing, some people dose a week's worth a time. I think it's better to do it in small increments of course, but it goes to show it's not always catastrophic to have too high Ca in go (within limits of course).

It's possible that the excess Ca just precipitated out of solution though. This can be compounded if your Mg is low. Many times people complain that they can't get Ca high enough and it turns out to be a low Mg issue.

I would check your pump impellers for Ca buildup. That will be where it will accumulate the worst. A vinegar bath ought to fix it all up if there is indeed a Ca coating on them.

FWIW I run my dosing on the Apex using an 8 hour cycle using the OSC function, and I offset the Ca/Alk dosing by 4 hours by making one of them have the pre-off value at 240 minutes whereas the other is at 0, then the on value is however minutes is needed, and the post-off value is whatever the on is taken away from the first two values to make a total of 480 minutes.

I'm tempted to shorten the intervals to make more doses over the course of a day but I haven't put too much thought towards it yet. In fact the only reason for the 8 hour cycle is that I was using programmable appliance timers prior to the Apex and I didn't want to have to adjust too many programs when I wanted to change a dose amount so I picked 3 times per day. I just carried that forward to the Apex so that there wouldn't be a perceivable change to the tank routine.

Anyhow let me know about the impellers, kind of curious to see where this goes. Good luck, hopefully nothing bad happens, pretty sure you're OK but good luck anyhow. :)

[Reef Pilot]

Is it possible your Ca was lower than you thought it was beforehand?
No, like I said, the Ca was at 400 in the morning, prior to the extra dosing. And 420 is not high, so definitely not going to tear my pumps apart to check for build-up. I check my Ca and Alk every few days, and keep my Ca between 380 and 420 normally. When it drops down to 400, I up the dosing time a bit, and it usually takes a couple weeks before it hits 420 again, which is when I lower the time until it gets back down to 400 (usually within a few days). So, even with the extra dosing, it did not exceed its normal range.

As for Mg, I use the Seachem Advantage Calcium for dosing, and it adds Mg in proportion to Ca. Every time I check Mg, it is on the high side, usually between 1400 - 1500, and lowest I have ever seen it was 1350.

Hence, I never have to dose Mg separately. I didn't check it now, but would expect it to be up actually, with the extra Ca/Mg dosing that happened.

[Delphinus]

You sound like you're set then ... cheers.

[Reef Pilot]

Well, I just tested my Mg, and another surprise. It was on the low side at 1350. I expected it to be higher with all the dosing. Of course, I don't know what it was just before the over dosing. I hadn't tested Mg since Jan 13 (I keep a log), and it was at 1440 then.

So, while all this doesn't make total sense to me, my params are still within range, and corals all look fine.