Ph meeters

LeastExpectedGrower said:

Yeah, from first use it's been that way. It calibrates fine (though that takes time too) and it's accurate, but it just takes a long time. I actually often use the 'hold' function in the middle momentarily so that it doesn't shut itself off while it crawls downward. Definitely takes minutes not seconds.

Click to expand...

If it was that way from the start, I can only assume it was a manufacturing defect or damaged.

There are some things that can be done to re-condition probes, I did this a few years back after some abuse. Lot's of good info on this site.

From my notes back then...
Take 21.46 mL of 37% HCL and add slowly in water to make volume up to 500 mL. Final conc. will be 0.5M HCL.
.1M =1pH
.2M=.7pH
.5M=.3pH
1 M=0pH

More links

Delps8 said:

AC Infinity has a couple of meters. If I weren't elbow deep in Bluelab, I'd be tempted to give them a try.

Click to expand...

Personally, I'd go with a company that makes PH meters and other similar instruments like Apera, Milwaukee, Hanna etc.
On the other hand, it looks like the AC Infinity meters are made by Apera. The only difference I see is they are black rather than blue. It's possible they are made to different quality standards though.

1212ham said:

Personally, I'd go with a company that makes PH meters and other similar instruments like Apera, Milwaukee, Hanna etc.
On the other hand, it looks like the AC Infinity meters are made by Apera. The only difference I see is they are black rather than blue. It's possible they are made to different quality standards though.

Click to expand...

I understand the idea of sticking with a "known quantity" but, as you point out, it's probably an Apera OEM unit. I like the idea of a replaceable sensor.

Re. quality being different - I don't know much at all about that aspect of manufacturing. I do get the concept, having been in the personal computer world since…forever. Years ago, when Apple bought hard drives they paid a premium for their drives because they set a quality standard. That was a purchase of hundreds of thousands/millions of drives and the production lines were set up to handle that.

OTOH, the production line for a pH meter is "somewhat smaller", one might say. Is it realistic to expect that even a limited run product like that has sufficiently different failure rates that they could separate them out?

I'm not arguing here, please understand. I'm a software guy so the hardware side is a different world and I do appreciate learning from other folks who have that sort of experience.

Oh, thanks for posting those links re. pH. Much appreciated.

MickFoster said:

Never wrong.......no calibration required.
View attachment 5346715

Click to expand...

I have the same one lol.

1212ham said:

If it was that way from the start, I can only assume it was a manufacturing defect or damaged.

There are some things that can be done to re-condition probes, I did this a few years back after some abuse. Lot's of good info on this site.

The pH electrode I have been using no longer seems to work or is slow to respond. Is there anything I can do to fix it? - Technical Information Library

When testing a pH Sensor (, , ), it is best to place it into a known buffer solution. This allows you to see if...

www.vernier.com

From my notes back then...
Take 21.46 mL of 37% HCL and add slowly in water to make volume up to 500 mL. Final conc. will be 0.5M HCL.
.1M =1pH
.2M=.7pH
.5M=.3pH
1 M=0pH

More links

Correct Handling and Care of pH meter

A laboratory may not be equipped with sophisticated instruments such as AAS, GC, HPLC, LC – MS or FT – IR but it simply cannot do without a pH meter as pH measurement is a basic requirement for all chemical and biochemical reactions and process control reactions in manufacturing industries.

lab-training.com

pH meter

www.ph-meter.info

Click to expand...

"Take 21.46 mL of 37% HCL and add slowly in water to make volume up to 500 mL. Final solution will be 0.5M HCL."

I just noticed an error in the sentence above. HCL should be HCI, Hydrochloric acid. Sorry for any confusion.

GrowBoxBudGuy said:

You never answered whether you have tried calibrating those two meters... I've used a few of the "cheaper" meters and some work better than others, even two new identical meters - even after calibrating... The cheapo I'm using now is remaining accurate and I keep calibration solution in jars for checking/calibrating...

Just received a "better" multi-meter (pH/PPM/EC) that I will be returning as it seems to have a cold solder joint on the circuit board that is keeping TDS/EC functions from working properly... When switching mode from pH to PPM it may or may not flash a reading for a split second before reverting to zero and only once displayed an EC reading before reverting to zero... Replaced the batteries with new and had the same results...

My advice, always keep new batteries onhand, preferably 357/303 Silver Oxide instead of the cheaper LM44 Alkaline's they come with... The 357/303's last far longer and give steadier readings... Well worth the extra expense...

Click to expand...

I wanted to follow up on my previous post... I did receive a replacement multi-meter and was disappointed again... The hot-swap replacement arrived and upon testing it I had opposite results... The EC and PPM functions worked but no pH reading at all... Zero for two... Amazon credited me without my need to return...

I ended up talking on the phone directly with Andrew from Aero-Gro.com, located near Allentown PA, regarding his Pro 5-in-1 Meter which he sells on his site as well as on Amazon... We had a lengthy conversation and I was surprised when he called rather than simply replying to my email... While the meter sells for less on Amazon I decided to buy direct as he stated he would calibrate both pH and EC prior to shipment... The meter arrived with a label indicating calibration date... I have been very pleased with the meter to date...

In addition, the seller of the two previous bad meters sent me a third unit, for free, for my troubles for testing... This third meter works for all functions but doesn't read the same as the Aero-Gro meter, but is fairly close... I haven't taken the time to calibrate it as yet but will in the near future...