Ph Monitor vs. Ph Kit?

[Inno]

Hello, just curious as to what tends to be more accurate more consistantly, a regular test kit such as Salifert or a monitor such as PinPoint?

*Those **** probes are expensive! :s

Thank you!

[Inno]

I wouldn't be monitoring the system at all times, but would use the monitor during maintenance (an overall check) or dosing with Bi-Ionic or limewater. What I am unsure of is if a monitor is more accurate/reliable than a Salifert test kit?

[captexas]

In my experience, even the quality test kits like Salifert are difficult to get a real PH reading as you are trying to compare colors on a card with the color of the liquid in the test vial. Rarely do they match anything for sure. I have a PH monitor and as Josh mentioned, it does have to be calibrated every so often and the probes are supposed to be replaced every 6 months which is not cheap either. Also, if your battery is weak, I have found it will give you false readings. They are nice, but do need to be maintained.

[Inno]

That's what I am worried about. The probes should last 18mnths on continuous use (according to manufacturer), so I am wondering how often it would last me since I would only be using it every so often: water changes (random maintenance check) and adding Bi-Ionic?....hmm hmm hmmm.....

[captexas]

Once you use the probe, you must keep the tip wet at all times or it will go bad. I'm not sure if you simply keep the power turned off if that will improve the life of the probe or not. All I remember it saying was that keeping it off will save the battery.

[Inno]

You can store the probe within a special solution, which is reuseable.

I just talked to the manufacturer (very arrogant) and he stated that using the Ph monitor as needed (not continual) and then storing within a solution will greatly enhance its longevity past 18months.

[captexas]

I don't know about the reuseable idea. One problem with the calibration fluid is that when you are moving the probe back and forth between the two fluids to get it calibrated, each test fluid gets contaminated by the introduction of any fluid remaining on the probe. And, over time the fluids are not as accurate.

[Inno]

The fluid used to store the probe is not the stock calibration fluids so after each use you can clean the probe and store it within the special solution, according to manufacturer. I'm just wondering what is cheaper in the long run, salifert (not exactly cheap) or the monitor (probe replacement is expensive)?

[Inno]

Where'd you find the handheld, if you don't mind? :) Is there anything to replace on it?...I take it calibration is still necessary? :)

[Inno]

Of course I would ask ;) I just checked customaquatic and there they are!

So how often do you have to calibrate that lil sucker? Did you test it against the Pinpoint just to see how accurate it is?...inquiring minds and all...;)

[GaryP]

OK, here is what an old lab rat that used a pH meter daily as one of his tools has to say about it.

1. The "special" storage solution is potassium chloride. This resores the potassium ions inside the probe.

2. I think that continuous use is a problem. The reason is that a film will develop over the electrode preventing it from operating properly. I suppose this can be overcome by VERY routine cleaning. I think that continuous use would eventually deplete the potassium ion in the electrode and thus shorten the life expectancy of the electrode.

3. We always calibrated our meters on a daily basis.

4. Electrodes should be cleaned with RO or distilled water after use, but never stored in RO or distilled water.

5. Small pocket sized pH meters (similar to TDS meters) are available. I have one. Another alternative are test strips, but I am not sure whether they are available in salt water pH ranges. The ones I used were 0-14, but I know theat more specific ranges are available. I will do some checking to see if a sea water range
(7.5 -9.0) test strip is availabe.

Gary

[GaryP]

Pocket pH Meters:

http://www.professionalequipment.com/xq/ASP/id.6/subID.263/qx/default.htm

http://www.sciencelab.com/page/S/CTGY/21771

http://www.hydroponics.net/c/64

[GaryP]

It looks like there is a test strip available from pH 6.5-10. Its accuracy is only about .2-.5 pH units though. It would tell you if there was a major problem, but not give you a specific pH value.

Gary

[Inno]

Thanks for the heads up Gary! Which Pocket tester do you own? I read through the links and am interested in this one: http://www.sciencelab.com/page/S/PROD/21771/50-HI98128

One thing none of the articles mention, unless I missed it, is how long before the electrodes (probe?) wear out...usually?

[GaryP]

I have an Orion. That's more of a professional model that I got through my old job. Its a bit pricey for a hobbyist. It depends on how often you use it and if you store it properly. I'd say they are good for 1-2 yrs. if used correctly.

Gary

[matt]

I have a dip probe called "the mini checker" that cost about $20. I don't store it in solution, just rinse it out after every use and put the cap back on. I do claibrate each time I use it, though. You can get calibration fluid pretty cheap ($10/pint) at analytical scientific.

[GaryP]

Matt,

Inside the cap should be a sponge that you can soak with storage solution. You can use pH 7 calibration standard as storage solution. The important thing is that you don't want it to dry out. RO water should never be used as storage solution.

Gary

[Inno]

Did some digging and found another handheld:

http://www.coleparmer.com/catalog/product_view.asp?sku=5900170&cls=15701&par=&cat=&s ch=875&pfx=&lstBool=true

This one was recommended by Randy on RC.

Thanks for all the help Gary :D