PH issues

O

omahaduke

New member
I seem to be having wild swings in my ph, and ORP. See below, I exported data from my Aquacontroller.

Date Tem PH ORP
11/7/2010 14:00 78.7 8.51 348
11/7/2010 15:00 78.8 8.49 349
11/7/2010 16:00 78.8 8.6 343
11/7/2010 17:00 78.9 8.63 341
11/7/2010 18:00 78.2 8.73 336
11/7/2010 19:00 79.4 8.76 335
11/7/2010 20:00 78.6 8.8 332
11/7/2010 21:00 79.2 8.82 331
11/7/2010 22:00 78.6 8.81 332
11/7/2010 23:00 79 8.78 335
11/8/2010 0:00 78.7 8.77 335
11/8/2010 1:00 79.2 8.56 346
11/8/2010 2:00 78.7 8.59 345
11/8/2010 3:00 79.5 8.19 367
11/8/2010 4:00 78.6 8.17 369
11/8/2010 5:00 79.4 7.5 408
11/8/2010 6:00 78.4 6.53 466
11/8/2010 7:00 79.1 6.53 466


Any idea what I can do to stabilize it?
 
A pH swing from 6.53 - 8.82. That is quite a bit.

What are you dosing to your tank as far as any kind of buffer or alk supplement and how are you doing it?

Have you recently calibrated your pH meter using both standards (7 &10)?
 
Those numbers aren't credible, IMO. I suspect measurement errors in the high pH numbers, unless the tank is getting a lot of kalk. At 6.53 the live rock would be bubbling and everything would be dead, so that number can't be accurate. I would check for electrical interference or calibration problems with the probe.

How recently was the pH probe calibrated and cleaned? Is it in a dark area, or does light hit it? Light can cause algal growth on the probe (ORP or pH), which makes the readings meaningless.
 
The number may not be credible but they are definitely going up and down in proportion with each other. That doesn't seem to be a coincidence.

Can you give a 24 hr read out? Are the numbers pretty close at the same times of the day or night day after day?
 
Last edited:
The really interesting thing is that the PH seems to go up when the display lights go out and the fuge light and moon lights come on..
 
Sounds like electrical interference with the lights, which seems to be a fairly common problem. That would make sense as to why the very unusually (not believable) high and low pH levels.

If you have a battery pH meter and remove a sample & compare the two, this would help determine what is going on with your light circuit interference.
 
SO....in my on going PH troubles, for the last 24 hours I have been hanging pretty consistant.

11/8/2010 23:00 79.3 7.79 388
11/9/2010 0:00 78.5 8.07 371
11/9/2010 1:00 79.4 8.25 360
11/9/2010 2:00 78.6 8.39 353
11/9/2010 3:00 79.5 8.48 347
11/9/2010 4:00 78.5 8.56 343
11/9/2010 5:00 79.4 8.6 341
11/9/2010 6:00 78.4 8.64 340
11/9/2010 7:00 79.3 8.64 340
11/9/2010 8:00 78.5 8.64 341
11/9/2010 9:00 79.1 8.63 340
11/9/2010 10:00 78.9 8.61 342
11/9/2010 11:00 78.9 8.64 341
11/9/2010 12:00 78.8 8.65 340
11/9/2010 13:00 78.8 8.66 340
11/9/2010 14:00 79 8.66 340
11/9/2010 15:00 78.4 8.67 339
11/9/2010 16:00 79.1 8.68 338
11/9/2010 17:00 78.8 8.68 338
11/9/2010 18:00 78.2 8.62 335
11/9/2010 19:00 79.1 8.59 334
11/9/2010 20:00 78.4 8.58 335
11/9/2010 21:00 79.3 8.57 337
11/9/2010 22:00 78.3 8.6 336
11/9/2010 23:00 79.3 8.59 337
11/10/2010 0:00 78.2 8.55 340
11/10/2010 1:00 79.2 8.47 345
11/10/2010 2:00 78.4 8.29 355
11/10/2010 3:00 79.1 8.31 354
11/10/2010 4:00 79.1 8.25 359
11/10/2010 5:00 78.7 8.2 363
11/10/2010 6:00 79.4 8.2 363
11/10/2010 7:00 78.3 8.1 370
 
It's very unusual for a hobby tank to have higher pH levels than 8.5, unless you are growing sea grass in your tank or adding to much kalk water. :)

That said, I still don't trust the accuracy of your pH measurements.
 
on 11/8 when the ph was around 6.0 I added about 6 teaspoons of Kent ph buffer, I havent added anything since. I am waiting for a few days before adding anything else. I don't grow sea grass, but have so GSP that it looks like a field!!!!
 
So..........I shut down pumps to feed last night and my PH dropped to 5.84, within 2 hours it was right back to the 8.00 area!

ARG!
 
Sounds like a bad probe. Make sure your temp probe is close to your pH probe. I believe the aquacontroller uses the temp probe as a ground reference for the others. I'm pretty sure your pH did not go below 6 unless something is really bad amiss. It would be obvious from other signs.
 
Hmmmmmmmmmm. I have my temp probe in display tank and my ph and orp in the sump.

What would all of you recommend for placement of the probes?
 
Something is incorrect in the data being produced,in my opinion.

As noted by steamman, consistent inverse movement between ph and orp seems to indicate the probes are working, though and some level of swing in ph and orp is occuring. So it might be electrical interference or something elsewhere in the unit.
 
I would guess electrical interference, too, but that's hard to determine. The placements of the probes seem okay. I'd try moving the controller to a different circuit (moving its power lines away from any others) and testing a cup of water well away from the tank the next time the pH looks that far off.

I'd also get some Oakton one-shot pH calibration pouches. Maybe the calibration solutions are bad, but I suspect other issues are more likely.
 
I am goign to move all the probes to a different area of the sump. If that still produces weird readings, then I will try moving them to the display tank. If still getting weird readings, then I think I will move the head unit to a wall adjacent to the aquarium and see if that helps.
 
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