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Need help - TDS spike after power outage

ElleDee

ElleDee

Member
Joined
12 Mar 2022
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Location
Southeastern US
So I had a 36 hour power outage that I was caught unprepared for. I will spare the play by play, but the power is back on, filters are running, livestock is alive, and the water temperature is almost back to target after a 15-ish degrees F swing over that period, handled as gradually as possible.

There is some explainable weirdness in the tanks (lots of horny shrimp!) but one big mystery: my TDS shot up from about 200 to over 300 in every tank. What on earth?? There's no detectable ammonia and the TDS of my source water is the same as always. Anyone have any experience with this? I'm going to do more water changes as I get time, but I have no idea what the cause is or if there's something else I should be doing.
 
I think the TDS reading can be effected by temperature... have a Google for the science if someone doesn't pop in to expand. I can't remember the reasoning but that might be a starting point for research :) Glad your livestock made it OK!
 
ElleDee said:
my TDS shot up from about 200 to over 300 in every tank.
Click to expand...

What temperature did you measure it at? Most TDS meters got Automatic temperature compensation (ATC), but may not be totally reliable... you should do the measurement again when the temp reaches what you normally keep the tanks at.

Assuming you were measuring at a lower than normal temperature (without ATC) you would expect to have the TDS being below your nominal 200 ppm... as the electrical conductivity in a fluid - that our TDS meters actually measures - drops as a function of temperature.


ElleDee said:
There's no detectable ammonia and the TDS of my source water is the same as always. Anyone have any experience with this? I'm going to do more water changes as I get time, but I have no idea what the cause is or if there's something else I should be doing.
Click to expand...
No not even a gross ammonia spike would barely change the TDS... There is no obvious (known) reason to me why the actual TDS would spike due to a temporary drop in temperature. Even if you would have a lot of say organic decomposition it would take a while for that to break down and show up as TDS. Thats my guess.

What has happened to me a couple of times over the years is that I accidentally pressed the Calibrate button on my Hanna TDS meter which automatically resets it, which means I would have to recalibrate it using the calibration fluid.

ElleDee said:
There is some explainable weirdness in the tanks (lots of horny shrimp!)
Click to expand...
LOL thats what you get from a blackout!

Cheers,
Michael
 
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ElleDee said:
one big mystery: my TDS shot up
Click to expand...
Very interesting. Please, would you double-check to avoid mistake?
(I've got no explanation. That's why I'm curious.)
 
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@MichaelJ I was thinking you had it with a calibration issue - my pen has no such button and while it can be calibrated they don't make it easy and I have never done it. But my source water is the same as always, as was my remineralized water. So I'm not saying my TDS pen is objectively accurate, but it doesn't seem to be doing anything weird and new.

My new guesses are that the water picked up stuff sitting in the pipes for a day? Or from the pots it was heated in? Or from the plastic container of 90 degree water that was left floating in the tanks? I can test the last two possibilities tomorrow and see if I can recreate the issue. (That said, I don't like the implications of any of them, so I'm hoping I'm wrong.)

The livestock seems fine, so whatever happened it doesn't seem like an emergency.
 
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