Dr. Tester Update

[setsailsoon]

Folks,

Last November I started using a Dr. Tester portable pH probe due to my problems reading the different shades of red and orange on the liquid test kit that's so popular. I promised I'd follow up so here's my assessment:

Pro's

• It works great, is extremely reliable.
• My biggest concern was how well it would stay calibrated. It only required calibration a few times first few weeks and even then it was .1 ph unit. After 3 weeks it was never off again. Don't know how they do it in such a cheap device but sensor technology has improved dramatically in the last few years-maybe this helped.
• It's very quick but you do have to wait 20 seconds or so for the reading to stabilize.
• Reads full range. Phenol red's range is limited to about 7.0 to 8.0 so it is possible to accidentally get very high or very low pH and not realize it.

Con's

• The only problem I've had is the readings got very erratic - climbing and dropping the entire scale over and over... I thought it was fried. But I removed the batteries and found a little rusty corrosion on one of the 3 coin type cells. Cleaned it and works good as new. This happens every 3 months or so in the humid pool environment.

Conclusions and recommendations:

• This is a superb device for anybody that has color-blindness difficulties with the red-orange color ranges. It's actually also a good adjunct for the TF 100 test kit for anybody. I like to use the FAS-DPD for chlorine and not have to use the other drop test for pH. I find the oto chlorine test consistently runs lower than the FAS-DPD and I'm pretty sure the FAS-DPD is more accurate.
• Buy a small amount of pH 7 standard solution already made up. It's found on gardening sites very cheap. I got about a quart and that's probably a 10 year supply so get the smaller size.
• There are other brands that seem to have identical electronics. If anybody has experience with them please let us know in the replies. I'd avoid the ones that are around $10 as they are not temperature compensated. $7 more for temp compensation is worth it.
• I'll try some corrosion block on the batteries, that should help.

I hope this helps.

Chris

 

[pooldv]

Yes, FAS/DPD is more accurate than OTO, or DPD for that matter.

Does the probe have any limitations reading pH with higher FC levels?

 

[setsailsoon]

Yes, FAS/DPD is more accurate than OTO, or DPD for that matter.

Does the probe have any limitations reading pH with higher FC levels?

Thanks for the info on the FAS/DPD. Good to know!

I did some research on the probes and didn't find much useful other than a fact sheet put out by APSP. Here's a quote on pH meters:

"Portable electrochemical sensors and probes can also be subject to interferences. There are few interferences in pool water for pH probe measurements, other than dirty or poorly maintained probes. The interferences for pH testing with reagents mentioned above can be avoided with a pH probe. Calibrate probes on a regular basis with calibration solutions as recommended by the manufacturer. Rinse probes with distilled or deionized water before and after use. Most pH probes need to be stored in a storage solution or moist environment."


There are several different technologies out there and my electrode appears to be the gel-filled glass unit. It looks like there's also another ceramic electrode on the end. Maybe there's somebody here that is knowledgeable about recent advances in pH sensor technology?

Chris

 

[setsailsoon]

One other advantage of the meter is that it reads full range. As I'm sure you know the phenol red test stays about the same color above 8 and below 7 so an inexperienced person could get ultra low readings or ultra high readings and not realize it. Also, on the plus side for phenol red I read they now have additives in most of the phenol red reagents that reduce the interference of cl. Not sure what levels they go up to. I'll add this to my table above in case anybody refers to it in the future.

Chris

 

[mgmoore7]

The PH test is hard for me too since I am color blind. I usually get my wife or kids to help me with this one. Color variations are hard to teach to a color blind person.

I have used digital meters for years for hydroponic gardening and found them to be invaluable since the typical pool drop test does not get low enough and the strips were impossible for a color blind person like me to read and they are not reliable. The digital meters can be finicky and I have not found them to last really long overall. The units I have had are usually between 40 and $60 and have had reservations about the quality / results of the cheap ones like the Dr Meter PH Meter. With that said at under $20, I can buy 2-3 of them for the same price I have been paying for the more expensive ones.
Dr.Meter® 0.1pH PH002 High Accuracy pH Meter/pH Pen Tester with ATC(Automatic Temperature Compensation) LCD 0-14 pH Measurement Range: Amazon.com: Industrial Scientific

This is the most recent one I have been using and it has been the best so far of the several I have used over about 10 years and I have probably had at least 5 different ones.
Oakton EcoTestr pH 2 Waterproof pH Tester, 0.0 to 14.0 pH Range: Science Lab Ph Meters: Amazon.com: Industrial Scientific

So far, I have not been using a digital meter for the pool but will probably switch soon once I get some time to be sure that my probe is in working order. I don't worry about PH nearly as much anymore for my hydroponics since I use rain water and find that it does not need adjustment compared to tap water.

One thing to note is that I recall reading the the calibration solution does not last very long once open and thus I switched to buying the one time solution packs.

 

[pooldv]

The phenol red PH test is only valid with FC up to 10 ppm.

 

[setsailsoon]

The PH test is hard for me too since I am color blind. I usually get my wife or kids to help me with this one. Color variations are hard to teach to a color blind person.

I have used digital meters for years for hydroponic gardening and found them to be invaluable since the typical pool drop test does not get low enough and the strips were impossible for a color blind person like me to read and they are not reliable. The digital meters can be finicky and I have not found them to last really long overall. The units I have had are usually between 40 and $60 and have had reservations about the quality / results of the cheap ones like the Dr Meter PH Meter. With that said at under $20, I can buy 2-3 of them for the same price I have been paying for the more expensive ones.
Dr.Meter® 0.1pH PH002 High Accuracy pH Meter/pH Pen Tester with ATC(Automatic Temperature Compensation) LCD 0-14 pH Measurement Range: Amazon.com: Industrial Scientific

This is the most recent one I have been using and it has been the best so far of the several I have used over about 10 years and I have probably had at least 5 different ones.
Oakton EcoTestr pH 2 Waterproof pH Tester, 0.0 to 14.0 pH Range: Science Lab Ph Meters: Amazon.com: Industrial Scientific

So far, I have not been using a digital meter for the pool but will probably switch soon once I get some time to be sure that my probe is in working order. I don't worry about PH nearly as much anymore for my hydroponics since I use rain water and find that it does not need adjustment compared to tap water.

One thing to note is that I recall reading the the calibration solution does not last very long once open and thus I switched to buying the one time solution packs.

Matt,

Thanks so much for the follow up. I may try one if my Dr. Meter ever fails. So far it's only been corrosion in the batteries... fingers crossed. I'm not completely color blind but I do have trouble with these shades of red/orange. Somebody on here said it's a fairly common in men since it's due to a sex-linked gene.

Before I found this tester I would run the oto test all the time and just do fas-dpd when I had a cl level concern. Now I do it the other way around, I run the much better fas-dpd FC test with my Dr. Meter for pH and get out the old oto phenol red kit once in a while just to compare it.

Chris

Chris