Aftermarket pH electrodes- any experience?

[Darklight]

I have a lovely digital pH meter which has been a rock solid unit for 15 years. It's a corker

But now the electrode is almost out of juice, and it isn't refillable ( I checked the manual )

15 years is pretty good lifespan for an electrode ( I calibrate regularly ). But I priced an identical new electrode at $260 from the manufacturer

pH meter has a BNC connector. There are a shit ton of aftermarket BNC connector pH electrodes on ebay for about $35

Anyone had any experience with using an aftermarket cheapie electrode attached to their lovely branded desktop pH meter?

I'll do a side by side with the old electrode and a regular calibrate of course

But if most people's experiences of cheap aftermarket pH electrodes is bad, I won't even bother waiting the 2 weeks for one to arrive from overseas

[Bigred]

i got a new one from blue lab it was 70 bucks but worth it as it is very sensitive and well built

most hydro shops can order them if not in stock

[Darklight]

.... and the answer is NAAAAHHH

Not all BNC connector pH probes will work with all meters

It could be because the one I borrowed to use on my unit was a combines pH and temperature meter, whereas on my unit the pH and temp are separate probes off separate plugs

I couldn't calibrate the meter while it was on there, there was too much difference between the electrode reading and the buffer pH for the calibration to be accepted

And there is no trim on the unit to be able to manually set the pH

It's a bugger, I need a precise pH reading and no paper strips I have are sufficiently sensitive to give direct and replicable colour changes, even tho I have a pH 4-7 paper set

Might take it into a pet store and test it with the aquarium pH probes

Good news is I found a cheaper Hanna genuine probe. Bad news is it's still $130AUD. I don't want another unit, I want this one to work

[Tripyamine]

I use a $20usd (shipped) blue plastic probe from Aliexpress, this is wired up to a simple pH circuit and fed into an ADC and to an Arduino monitored via the serial out

This sits in a saltwater frag tank all day and the data gets logged to a xively feed; when the lights come on there is a nice shift from the photosynthesis kicking in, and it's all exactly the same as the colorimetric 7 to 8.9 test kit that I have which is highly regarded (sailfert)

As for probe calibration, Im sure you're aware that 99% of calib is done by cleaning the probe/keeping it clean

I use a 12 bit ADC and this generates a value between 0-4096 which is directly proportional to pH

The main calibration factor used is drift, which is the measure of how different the probe's reading is to a "new" probe if that makes sense

[Darklight]

I use a $20usd (shipped) blue plastic probe from Aliexpress, this is wired up to a simple pH circuit and fed into an ADC and to an Arduino monitored via the serial out

This sits in a saltwater frag tank all day and the data gets logged to a xively feed; when the lights come on there is a nice shift from the photosynthesis kicking in, and it's all exactly the same as the colorimetric 7 to 8.9 test kit that I have which is highly regarded (sailfert)

As for probe calibration, Im sure you're aware that 99% of calib is done by cleaning the probe/keeping it clean

I use a 12 bit ADC and this generates a value between 0-4096 which is directly proportional to pH

The main calibration factor used is drift, which is the measure of how different the probe's reading is to a "new" probe if that makes sense

Nice workaround

I might have to risk a probe shipped from China as long as the specs match mine. I do need it now tho and shouldn't risk the shipping lag esp if it doesn't work, but $ is the limiting factor this week

As for the rest, to set something up similar to that would be more than the cost of a manufacturer's probe from Amazon and take me a few weeks to work out, it's not an option right now as I don't have Arduino capacity

But yeah, I love all that DIY stuff when I have time

Edited May 21, 2015 by Darklight