Recommendation for Ph Pen?

[nicklimzhiwe]

Hi people..

I remember hearing someone talk about an item called the Ph pen before in this forum.. Supposedly its use to test the Ph of the water in the tank..

Now I feel like getting one myself.. But I do not know which brand to get, where to get, or the price for one.. Of course I'd like to get a new one.. So any recommendations?

Thanks a lot in advance..

Regards
Daniel
A.K.A
Zhi Wei

[Fuzzy]

Hanna or Milwaukee instruments are the 2 brands I'd recommend, most of the guys here are using one or the other.

Not exactly cheap though, myself I just use API pH test kits, I don't do it often enough to justify buying a pen :P

[nicklimzhiwe]

I'd love to do random checks on my tank's water's Ph.. So the pen would be super convenient for me..

But where do I get one?

[Fuzzy]

You can try NA, C328, Sim Lim Tower (not square) Basement 1. I forget the shop name, but take the stairs down, its the first store to your left beside the escalator.

Expect to pay between $60 and $120 depending on brand and model.

[GaspingGurami]

The cost of the instrument is one thing. Maintenance and calibration is another.

You see, buying an expensive pH tester and testing your water while it is mis calibrated, is worse than not testing at all, because you'll base your dosing on the incorrect results and make unnecessary, possibly damaging changes.

Therefore, with a pH pen, you actually end up doing more testing than you think - you test the probe's calibration first, rinse off the test buffer, before doing the water testing. Then, you have to clean the probe thoroughly again and store in its storage solution if you want your probe to last.

Which brings me to the next point: Your pH probe will not last forever. 3-4 years if treated well and only used to test aquarium water. It can very quickly made useless if you don't take care of it. (I made the mistake of storing my probe in distilled water than in the storage solution which promptly killed my probe in a month's storage). Storing it dry also shortens it's lifespan.

All these means you may not recover your capital investment in the electronics if you are thinking that way for the long term, compared to using pH testing reagents. But if you have a hundred tanks that need your testing of pH, then perhaps it makes sense in getting a pH pen for the time saved.

If you still decide to get a pH tester, I'd then suggest getting the best that you can afford to pay than buying the cheapest. Things I consider necessary are:
1) Automatic Temperature Compensation (ATC). Because the pH of a solution (even your test buffer) changes with rising and falling temperature, an ATC pen saves a lot of other calculations in compensating for temperature differences. (if you don't do this for a non ATC pen, you may actually be mis calibrating it because of temperature differences)

2) Getting one that offers 2-point calibration is more accurate than a single point. 2-point calibration allows the pen to be calibrated at pH 7 and pH 4.

3) Get one that uses the same storage solution as one of the calibration buffers so it saves you the cost and trouble of buying a storage solution and maintaining/cleaning 2 calibration buffers.

4) Get a more expensive model that allows refilling of the probe's electrolyte, and offers a replaceable probe. It may be cheaper in the long term than to buy a cheaper pen and throw when the probe expires.

5) If you have a habit of dropping things, get one that is shockproof, and has IPX 6 or higher rating.

6) Always buy fresh calibration buffers and use them before you test, unless you do testing 3 times a day. In that case, you should calibrate once at the start of the day.

Lastly, when is it time to replace the pen/probe? When it takes a long time to get a stable reading, your glass coating/electrode is probably worn. Try changing the battery to eliminate power problems and if it still takes a long time, bye bye electrode/pen.



HTH