The pH testing report

OK, testing pH is important, and it becomes burdensome when the number of tanks grow.

I've been making changes in my setup, in search of both accuracy, reliability and convenience.

At the moment, I operate only three tanks, which is near max capacity for the place where I live.

I've been writing about the experience on the forum at Everything Aquatic, as well as on this blog. Presently, things have changed quite dramatically with the arrival of a Hanna Instruments HI98121 pH/ORP/Temp probe, to complement my old HI98100 as well as replace a 17-year old Hanna ORP tester, and my trusty API pH test (the one with the 5 ml sample bottle and the 3 drops).

The specs are as follows:

• API pH Test Kit. Range 6.0-7.6, accuracy (implied) 0.2 (at least in the middle of the scale, where it matters)
• Hanna Instruments HI98100. Range 0.00 to 14.00 pH, resolution 0.01 pH, accuracy +/- 0.2 pH.
• Hanna Instruments HI98121, combined pH/ORP/Temp tester. Range -2.00 to 16.00, resolution 0.01 pH, accuracy +/- 0.05 pH.
• Seneye Reef: pH-monitoring comes as part of a comprehensive monitoring of ph, NH3/4, Temp, and light. Range 6.00-9.00, resolution 0.01 pH, accuracy +/- 0.15 pH. In this system changing the slide once a month is tantamount to re-calibrating the probe.

I have had extensive consultations with Hanna about the care and keeping of their testers, and with experience it is clear to me that these are worth having if you keep large numbers of tanks, but financially it is questionable when the convenience pays off, since I currently only keep 3 or 4 tanks. My 4th tank is really an emergency/hospital tank.

Notes from Hanna support

Here are some of the notes from email exchanges with Hanna Tech support, about the need to change and clean the electrodes and re-calibrate them:

Previously, they had suggested calibrating the 98100 at least weekly if it were in daily use, or simply weekly if I were using it weekly. The manual of the 98121 suggests a minimum of one calibration a month. It should be noted that the 98121 used more calibration liquid because the probe is bigger, I figure roughly one full 20 ml package of calibration liquid, vs about 5 ml per calibration for the 98100.



quote

When you change out the probe make sure you clear the calibration from the meter.

Here is the directions from the manual.

Turn meter on.

Place meter in calibration mode.

Press and hold ON/OFF until “CLr”

is displayed. The meter will now be

at default calibration. No tags will

be shown in measurement mode

until calibration is performed.

I would suggest you also calibrate the HI98121 regularly just like the HI98100.  Cleaning the electrode by soaking it in the HI7061L general purpose cleaning solution is also recommend at least once a week perhaps twice if using the meters many times every day.

You mention you are comparing equipment.  Keep in mind the HI98100 is an inexpensive tester.  It has an accuracy of +/- .20 so when you are in the pH7.01 buffer a reading from 6.81 to 7.21 would be within spec.
unquote (Hanna Support, May 16th, 2017)

quote

We do suggest frequently but since you are comparing it to the Seneye if they are reading close then calibration may not be needed.  In the end it is up to you how often you want to calibrate. 

You will need to clean the electrodes.  When you do use the cleaning solution you will definitely need to recalibrate the meter.

Clean the meters as followed:

Place into the cleaning solution for 15 minutes.

Remove, rinse in distilled water and place them in the HI70300L storage solution for 1 hour.

Perform the calibration before using the meter again.
unquote (Hanna Support, May 16th, 2017)

Economics

The simple comparison is this:

• API pH-test: 250 tests for $5, plus 5 minutes of your time for every test.
• HI98100 $41, plus a new probe every 6-12 months at $12, plus the chemicals for calibration, cleaning and storage, about $2/month. The testing takes only a minute, but you do have to do calibration and periodic cleaning, so for a small number of tanks it takes just as much time as the API test, if not more. If you need to calibrate this one every week, one 20 ml package of calibration liquid can last up to 2 months, because you only use 2-3 ml per calibration if you use a 5ml sample vial. I am assuming one package a month, at $1.50 each.
• HI98121 $179, spare electrode $55, plus chemicals for calibration, cleaning and storage, est. $3/month. Note that this device gives you pH/ORP/Temp. Calibration, cleaning and storage are similar to the HI 98100, maybe slightly less. If you need to calibrate only once a month, you need a 20ml package every time, for this probe is large.
• Seneye Reef $199 (basic configuration), with monthly new "slide" at $12/mo, or ca. $150/year. Note that Seneye gives you pH, NH3/4 (ammonia/ammonium), Temp, and light conditions, and they are working towards potentially including other measures. You an spend $300 more for the wireless, on-line version that works with WiFi, and is not dependent on a computer. Requires almost no time, except the seconds to look up the conditions in the tank, and once a month the few minutes to replace the so-called "slide."

In short, the comparison does not quite work, because the third and fourth options include so much else besides pH, so you have to look at your total requirements, and, particularly if you keep a planted tank, or a reef tank, the information on lighting is critical.

Convenience

For convenience the Seneye has it, hands down, but at the end of the day, it is the winner for economics also, if you realize the value of real time readings of free Ammonia, and the various other parameters, particularly lighting for the planted tank and reef tank keepers. You could have a fish tank and if you test for ammonia every 7 days, you might never know a fish died until you miss him, but if you see a sudden ammonia spike, you know either someone died, or your filter has a problem. The only alternative is the Seachem Ammonia-alert and pH-alert, which are $7.50 each and last 6 months, but they are quite hard to read by comparison. I would recommend them for any new tank setup however. It pays to watch the nitrogen-cycle build up in the early going, and to know exactly where you are. With Seneye, I can check the pH, ammonia and temperature on my smart phone anywhere on the planet, practically in real time.

I remember at one time having a 125 gallon tank in my living room, and when I traveled I was always concerned with the state of affairs in the tank, and my wife was not about to do any water tests... With Seneye, I just know.

The Program

As per the above, my first benchmark will be against the Seneye, once a week in the main tank, and if it matches closely fine, if not, I'll use an API pH-test as the referee, before doing a calibration (and cleaning as needed) on the HI testers.
I will continue to document the findings in a spreadsheet for at least six months, the normal (or at least warrantied) lifespan of an electrode, I'll do the comparison of all four. Weekly the 98121 against the Seneye and the 98100, and API pH-tests as and when needed.

I will publish the conclusions here, or maybe even interim results, if there is something interesting to discuss.
Meanwhile, thanks go out to the people at Hanna, Seneye and the indefatigable Carl Strohmeyer at American Aquarium Products for their great support.