Sudden PH drop

WhatCouldGoWrong71 · Jan 28, 2025

I’ve included images from my apex. I’m not sure what’s going on. The drop earlier in the week was a water change. I empty the sump for a water change. I have checked the usual suspects. A few things to note-

- PH is the only number I truly chase
- not sure why my CARX co2 is getting high, I have it programmed to shut off only when it is <6.68. Plus 6.80 should help ph.
- For DKH my Versa that drives my CARX is set to shut down > 8.6, Sodium Hydroxide shuts off at 8.6, Kalk shuts down at 8.99
- the decline in nightly PH is due to my kalk reactor needing service. It’s been at 12.1 for a couple days now.
- I buffer with 2 part (and for and in case CARX dies). I use sodium hydroxide.
- I’m really not sure why I am getting ph drift inside my CARX.
- I calibrated all my PH probes the same day I did my water changes, a couple days ago.

The drop is quick and hard. I have been putting that blue and white filter roll in my bubble trap to polish the water. I’m getting a little kalk build up, but this is a normal amount I would typically see after having it in there for 2-3 days. I mix my kalk reactor ever 20 minutes for 90 seconds. I do a near slurry that goes through an L2 and then out in to my tank. I touched the white area on the filter roll and it is not hard. It is clear that that the kalk liquid is easily making it into the tank while some of the by product is getting caught in the filter media.

WhatCouldGoWrong71 · Jan 28, 2025

The DKH14 is my Alkatronic.

edsbeaker · Jan 28, 2025

This is a bit outside of my comfort zone with this being pH with a CaRx, so forgive me if I’m way off!! Because it is a very sudden drop, could it just be an error?

Have you checked if the probe is submerged? I know it sounds obvious, but it’s happened to me.

Another possibility is air bubbles around the probe or it just needing a cleaning.

I hope someone can figure it out if it’s something else.

WhatCouldGoWrong71 · Jan 28, 2025

Correction: I calibrated probes a few days prior to the water change.

That’s the one thing I did not check. I also have a spare probe and a PM module that I can run 2 when I get home from work. I put 10 ML of sodium hydroxide and didn’t see a bump. I’m at the office now. I may push 50 ML of this over 30 minutes. If I don’t see a rise in PH I likely have a probe issue. I’m 500g, so that amount won’t be a head ache prior to lights on.

WhatCouldGoWrong71 · Jan 29, 2025

@edsbeaker - so when I got home, I checked the physical probe. It was under water. But interestingly, some how my intake line for my CARX got free and was pinned against the end of my PH probe. The second I moved the intake and resecured it, you can clearly see the straight line up. My PH jumped to 8.35 instantly and then eventually hitting 8.6, I took the safety limit to 8.6 for my alk doser and wanted to make sure that the probe would follow it up. I surmise that because when my Versa on my CARX is off due to DKH safety point, I still keep the PH pegged in my CARX at 6.67ish that there must have been some lower ph siphoning out of my CARX through the Versa and right into the tip of my probe. Coupled with the end of the line literally touching the end of the probe. I’m at 8.14 as I type this at 6am which is about where I should be.