low pH pics

[NewSchool04]

I recently won a pH monitor and I'm getting some strange readings in the morning and I'm wondering if it's even possible. I'm getting a 7.3 reading some morning, not every day, about once out of 5 days. Usually I swing from 7.9 (dark) to 8.3 (all lights on).

Can a reef tank get down to 7.3?!

I have a 180 reef tank with 40 gallon sump.

[fish tanked]

I'd guess if it is just once in the 5 days that it is your probe being screwy. I assume you are calibrating regularly and are not reusing calibration fluids. You might also check and make sure that the the calibration fluids you have aren't old. I know that 10 buffers often expire quickly. If your ph monitor doesnt correct for temperature that could be an issue as well.

[VaderWS6]

When I first hooked up my Pinpoint pH monitor, it was reading up to 8.4 during the day, and 7.9 at night. I run a GEO kalk reactor, so these readings were expected. The week after, my pH readings were much lower (8.1 day and 7.8 night). I'm still not sure why they are so low, and I'll be recalibrating next week. Hopefully its just my monitor.

[NewSchool04]

Don't you think 7.3 is just too low. I wouldn't think that a salt water tank could even get that low.

[Boomer]

Let us know as I suspect the meter may have lost its calibration. Is this meter near any electrical outlets and are you running the meter on DC or AC power ?

Take a sample of tank water to some where else in the house and see if you get the same readings as in the tank

[NewSchool04]

I have the meter close to one of my 400W E ballasts. Would this affect the meter?

I'm not sure if it's AC or DC, not really up on my electric.

[dmilne85]

i noticed when my fuge light turns on for the night(150w hqi ballast) my ph meter will go funky for about 45 seconds, and then it is normal... maybe that is what you are seeing...?

[NewSchool04]

It's always in the morning with no lights on, so I doubt that that is what is causing it.

[bertoni]

I'd try measuring a cup of water well away from the tank. Does the meter run on batteries? If not, check the power cords carefully. If that doesn't fix the problem, I suspect recalibration is going to be necessary. 7.3 isn't possible, in reality.

[fish tanked]

Since a pH meter is just a glorified voltmeter if you have some stray current in your tank that will cause you to get screwy results. You might try like someone else mentioned and test some water NOT in the tank so as to isolate it from any potential current in your tank. That is a long shot though. You might also check how you are storing the probe. Are you keeping it in a particular solution? When you calibrate does it give you a slope, is it within the range it is supposed to be? Have you tried testing one of your calibration solutions with the probe to see if they read as the pH they are?

[NewSchool04]

I keep the probe in the sump, so it's not stored in solution. I did the test away from the tank and I got around the same reading as far as comparing color changes to an actual number.
When I woke up this morning my pH reading was 7.94 so I can't figure it out. Either its a problem with the monitor or the probe but it seems to come and go.

[bertoni]

That's going to be tough to diagnose.

[fish tanked]

I would try taking the probe out of your sump and putting it in some of the calibration fluid that you have poured into a really small container. This fluid is usually marked as different pHs eg: a 4.0, 7.0 and a 10.0 fluid. See if they test as they are labeled making sure to rinse the probe off in a separate container of clean water between each test. That is an easy way to rule out the probe as working correctly or not.

Also, look at where the probe is in your sump, is it really close to a heater or something else that gives off heat such as a pump? Is it getting directly hit with bubbles so that they can accumulate on it? Is it staying completely submerged?

Have you considered that the pH actually is swinging dramatically? How is the tank's livestock doing? Have you checked your Alkalinity lately?

[brad]

This much of a pH swing is probably an alkalinity problem no matter how far the probe is off. Get a good alk test, or better yet, get a good friend with a reef tank to double check both alk and pH readings. You can use kalkwasser or washing soda to slowly recover the alk if you are conservative even without a good reading, but your probably want to fix the probe first if you can.

One (somewhat risky) way to test your probe: Add kalkwasser until the pH reads just above 8.5 for and stays above 8.5 for 1 hour. If you cannot do that, your meter is reading low. If you can and the pH does not return below 8.4 after 12 hours you know your meter is reading high. Again, be careful, too much kalkwasser will do bad things.

I screwed myself by calibrating my meter too fast. I would put it in the 7 fluid, and wait 5 minutes and set it to 7. But I found it would keep dropping for another 5 minutes and I wasn't waiting long enough. So my 7 liquid read 7.5 and my 10 read 9.5. This may be an issue with me having an older probe I probably should replace, but a bad calibration job really throws the number. I only found this by accident by the method I just posted - I added too much kalkwasser my pH never went over 9 but was above 8.5 pH almost 24 hours later - I know that isn't possible.

[bertoni]

This article describes a safe sanity test for a pH meter:

http://web.archive.org/web/200210150...io/default.asp