Drastic PH Drop overnight....

Z06-Hec · Jan 6, 2015

Last night i turned off all 3 power heads for feeding time. After a while I turned everything back on but purposely left 1 power head off (the strongest one). I wanted to see how the fish would react to less of a flow in the tank.
Anyway I wake up for work around 4:45am always peek into the tank before I walk out the door and all looked fine...
On the bus my seneye sends an alert, PH too low to read...
Apparently the alert was sent overnight around 3:30am but in email so I didnt check email until i was on the bus...
So I text the wife to check the power head and turn it on before she left and she did. It looks like its going back up to normal readings..
So here are the shots of params ... The PH normally is around 8.11 and it went all the way down to 7.63 at its lowest point and is back up to 7.95 now.
Could the powerhead off create such a drop over night?

DFW · Jan 6, 2015

tigerdragon · Jan 6, 2015

Depends on how much it disturbs surface water where gas exchange occurs. But your drop wasnt that bad.

Z06-Hec · Jan 6, 2015

I do keep it pointed up to wave the water and offer exchange... just based on reading, i pointed it that way... Not sure if it was actually working.
I guess it does?

Z06-Hec · Jan 6, 2015

Ok so what is really low? Its since gone back down, right now at PH7.44, Temp 76.1 and NH4 is climbing at 67.99 Ammonia is still .001

tigerdragon · Jan 6, 2015

http://reefkeeping.com/issues/2007-02/rhf/#2. Check out this article by randy-harley holmes

tigerdragon · Jan 6, 2015

My bad randy holmes-farley

Randy Holmes-Farley · Jan 6, 2015

Z06-Hec said:
Ok so what is really low? Its since gone back down, right now at PH7.44, Temp 76.1 and NH4 is climbing at 67.99 Ammonia is still .001

The pH is now 7.44?

That's a testing error of some sort, unless you turned off all the flow.

Z06-Hec · Jan 6, 2015

Right now according to my seneye its 7.57
As soon as i can get home from work i will double check with my PH Pen.
All the flow is back to normal.

Temp 76.1F
NH4 50.4
NH3 .001

Z06-Hec · Jan 6, 2015

Seneye Reading
PH 7.23

Z06-Hec · Jan 6, 2015

now its 7.54
Something has to be up with the readings...
hopefully i dont come home to a shocked system.

Randy Holmes-Farley · Jan 6, 2015

You won't. It is an error of some sort.

Diesel · Jan 6, 2015

Can you monitor ALK and Cal?
With a PH drop like that your ALK might have a drop too, not much but some.
If ALK is OK Randy is right that your probe can be bad.
When is it that you checked your probe?

SeeingGreen · Jan 6, 2015

Randy, not to thread jack, but what would be a normal night drop? Or at least a feasible value?

redfishbluefish · Jan 6, 2015

You've got to have a bad probe.....that pH drop can't be real. And FYI, I'm pretty sure Seneye doesn't actually measure NH4....it's calculated off on the measured NH3 number and pH. That's why you're seeing a similar rise in NH4....it's calculated from your apparent drop in pH.

Curious, do you have a carbon monoxide detector in your house?

Z06-Hec · Jan 6, 2015

i cant monitor it but i did a reading on sunday.
Cal was 430
Alk was 9.9
Mag was 1140 or so.

Z06-Hec · Jan 6, 2015

redfishbluefish said:
You've got to have a bad probe.....that pH drop can't be real. And FYI, I'm pretty sure Seneye doesn't actually measure NH4....it's calculated off on the measured NH3 number and pH. That's why you're seeing a similar rise in NH4....it's calculated from your apparent drop in pH.

Curious, do you have a carbon monoxide detector in your house?

you know actually.....
I let my slide expire a few days back and have not replaced it. I started prepping the new one on sunday, they need to soak in current water for 48 hours before replacing. The current slide has been expired for about 9 days already though.
Funny thing is i have been wondering what happens when they expire. According to the monitoring software all that happens is you dont get alerts.
Well 9 days expired and i got an alert of the PH dropping low...
Not sure if that has anything to do with the accuracy though...
Either way I will test with my PH pen and change my slide today.

As for carbon monoxide, im pretty sure my fire alarm detector is combined... Carbon Monoxide/Fire Alarm

Randy Holmes-Farley · Jan 6, 2015

SeeingGreen said:
Randy, not to thread jack, but what would be a normal night drop? Or at least a feasible value?

The diurnal pH change can range from almost nothing (with very good aeration) to several tenths of a pH unit. 0.1 to 0.3 pH units is very common.

In this case, it is the pH numbers down in the mid to low 7's that tells me it isn't real (barring something very unusual, like a gas fireplace not being vented and building up tremendous CO2, which is probably also why Redfish asked about a CO detector), not the change itself. Aragonite begins to slowly dissolve at a pH not too far below 7.7, and I usually recommend pH 7.8 as the minimum I'd want to see at night in a reef tank.

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