High Tide Aquatics

Ph probe accuracy

newfly

newfly

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I have been relying on ph value from Alkatronic. For fun I bought a standalone wilwaukee ph monitor mc120. Calibrated both Milwaukee and Alkatronic just now. Both are within 0.01 before adjustment/calibration.

Run test on both :

Milwaukee - 8.6
Alkatronic - 8.1

Kalk at 8dkh

Both numbers are fine. The real ph is probably somewhere in the middle .

Any idea what causes the difference?
 
My alkatronic probe always reads a good bit lower than the main probe, I think it is because the reagent is acidic.

Also most hobby PH probes are basically inaccurate and cannot be trusted so you’re just kind of chasing your tail anyway. Sometimes my Milwaukee stays calibrated for a good while and sometimes it starts to drift within days. 8.6 is probably wrong, for example.
 
when I use to use probe I it’s best not to keep in the salt water 24/7 . I had 4 ph setup and the testing each brand gave diff settings.
But running a co2 reactor u needed to measure in and out ( min of 2-3)
It was a pain weekly cleaning and calibration if you want Accurate reading.
I would retire probes every six months.
I would clean daily
My 2 cents …..lol
 
Good to know it’s not unusual for the numbers to be off. I got the second ph probe to track significant ph driff .

Stupid question. I have a hard time opening the brand new ph probe protective cap. Any tips? On the wilwaukee I ended up breaking one of the protective plastic thing on the probe ( near the glass sensor). The probe still works well for the ph 4 and 7 calibration fluid.
Is the cap twist off?
 
newfly said:
Good to know it’s not unusual for the numbers to be off. I got the second ph probe to track significant ph driff .

Stupid question. I have a hard time opening the brand new ph probe protective cap. Any tips? On the wilwaukee I ended up breaking one of the protective plastic thing on the probe ( near the glass sensor). The probe still works well for the ph 4 and 7 calibration fluid.
Is the cap twist off?
Click to expand...
You mean the cap with the liquid that you use to store it? I believe it’s just a simple o-ring seal. Twisting gently certainly helps.

I finally ponied up for a decent lab grade PH tester, mainly to check my kalk saturation. It’s not stored in SW and seems to be staying fairly well calibrated so far. If you really care, you could get one of these - but it’s more work to use and not continuous data obviously
 
newfly said:
Good to know it’s not unusual for the numbers to be off. I got the second ph probe to track significant ph driff .

Stupid question. I have a hard time opening the brand new ph probe protective cap. Any tips? On the wilwaukee I ended up breaking one of the protective plastic thing on the probe ( near the glass sensor). The probe still works well for the ph 4 and 7 calibration fluid.
Is the cap twist off?
Click to expand...

I try to screw the cap open. This typically works and I had the same issue on some of the probes possibly due to the storage liquid.

I have Milwaukee probes on all of my devices - Apex and Hydros, and I also have the Milwaukee controller, as well as the Milwaukee MW102 PRO+ which Meckley used/uses for his coral farm for Kalk saturation, and which seemed very reliable

I only this type of probe though, and have not experience with the others (except for the MW102 which uses a different probe model (SE).


On a related note, it sounds like the ICP machine manufacturers recommend to calibrate PH probes with 4 and 7 PH fluid vs 7 and 10 for greater accuracy for our purposes - I have not switched yet but Fauna Marin has all their probes in their farm calibrated this way.
 
Update on this thread. The next day the delta btw the 2 probe getting smaller. This morning, Alkatronic reported 7.9 , Milwaukee 8.1

Looks like it need a couple of days to stabilized?
 
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