Very sudden pH drop

[aldrichg9]

Hello,

My tank pH apparently dropped suddenly from 8.46 to 8.02 from one reading to the next maybe 20 minutes (see screenshot below)

Tank has been set up 2 years this month (125 with large sump and decent skimmer)

Has 5 fish (clown pair, dottyback, puffer, velvet damsel)
Mushrooms, toadstool, a couple other small corals
Everyone looks perfectly happy (haven't seen the brittle star as per usual)

SG: 1.026
Alk: 10 ish
Nitrate and Nitrate: both 0

ATO water has plenty of buffer and I had added water 2 days before this happened. It was topping off normally maybe every 2 hours and pH was going up as expected.

I was out of town and didn't add anything to cause this

Has anyone seen this before

 

[taricha]

I feel its much easier to explain how a probe can quickly change reading (water level, electrical interference, got bumped etc) rather than how the water without obvious intervention can actually change pH that much, that fast, and show no dramatic changes prior or after.

 

[rtparty]

How old is the probe?

 

[Court_Appointed_Hypeman]

Everytime I experienced something like this, calibration helped. Cleaning the probe may also be necessary

 

[MnFish1]

If someone is housesitting - you could consider if they changed the window situation or the furnace situation - or they could be having a large party. If not - as others have said - consider the probe

 

[aldrichg9]

The probe is about 6 months old

Had been thinking if a probe went bad it or out of calibration it would either go completely dead as in off the chart high or low, or slowly it would change.

I don't currently have a cal solutions on hand or I would have done that.

Will have some this weekend.

 

[aldrichg9]

If someone is housesitting - you could consider if they changed the window situation or the furnace situation - or they could be having a large party. If not - as others have said - consider the probe

My girlfriend was here, but I am reasonably confident she didn't open any windows during the 35* rainy situation we had, or throw any parties.

She also has her own aquarium and is conscious of not adding or changing anything.

 

[aldrichg9]

Everytime I experienced something like this, calibration helped. Cleaning the probe may also be necessary

I swirled it around the water to try to clean it a little

Also thinking if there was debris affecting the reading of the probe it would happen over time.

 

[MnFish1]

My girlfriend was here, but I am reasonably confident she didn't open any windows during the 35* rainy situation we had, or throw any parties.

She also has her own aquarium and is conscious of not adding or changing anything.

Sorry the party thing was kind of a tongue-in cheek comment. I was about to make another one - but I think I'll leave it at 'until you can verify that the pH actually was 8.4 or 8.0 independently it's hard to say. It's usually an elevated CO2 (in the room) - that causes this - That, though is not immediate. I was trying to think of a reason besides 'error' that the pH would drop - so here is another question - from Morning to night - what is the swing - i.e. the low of the day to the high of the day generally?

 

[MnFish1]

My girlfriend was here, but I am reasonably confident she didn't open any windows during the 35* rainy situation we had, or throw any parties.

She also has her own aquarium and is conscious of not adding or changing anything.

BTW - it would be suddenly closing windows that would cause the CO2 to elevate lets say its raining - close the windows, the CO2 would rise (in the house)

 

[aldrichg9]

Sorry the party thing was kind of a tongue-in cheek comment. I was about to make another one - but I think I'll leave it at 'until you can verify that the pH actually was 8.4 or 8.0 independently it's hard to say. It's usually an elevated CO2 (in the room) - that causes this - That, though is not immediate. I was trying to think of a reason besides 'error' that the pH would drop - so here is another question - from Morning to night - what is the swing - i.e. the low of the day to the high of the day generally?

All good thanks for the replies

The only measurement method I have other than the probe is strips which IMO is a relatively subjective measurement

The swing is normally pretty small ~0.5

Because of allergies the windows in the house have to stay closed all the time, thinking it’s not likely to be a sudden buildup of co2

Will report back to this thread once I can calibrate the probe and have more reliable measurements

 

[MnFish1]

All good thanks for the replies

The only measurement method I have other than the probe is strips which IMO is a relatively subjective measurement

The swing is normally pretty small ~0.5

Because of allergies the windows in the house have to stay closed all the time, thinking it’s not likely to be a sudden buildup of co2

Will report back to this thread once I can calibrate the probe and have more reliable measurements

I thought at least at some point you were away from the house - perhaps my misunderstanding

 

[jda]

That is a testing error... bad probe or meter.

 

[Randy Holmes-Farley]

I agree that pH cannot change instantly, but a bad measurement can. A power blip can sometimes mess with calibration, for example.