Tropical Fish Keeping - Aquarium fish care and resources

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-   -   PH pen (http://www.tropicalfishkeeping.com/water-chemistry/ph-pen-5776/)

Robnjo 05-10-2007 11:33 PM

PH pen
 
I just got one of the PH digital pens but the manual don't make sense on calidration, form Hong kong :? ,

Q. What is the PH of distilled water?
Rob.

Mr.Todd 05-11-2007 01:20 AM

In theory the pH of pure water is 7.0. However there are alot of factors that can effect the readings of pH monitors other than simple H+ and OH- count in the water.

Here is a little snipit if you want to talk a little chemistry:

http://www.eutechinst.com/techtips/tech-tips48.htm


So unless you are working with EXTREMELY sensitive fish calibrating to 7 would be fine. (and in my opinion its still going to be alot more accurate than trying to eyeball colors on a chart)

:-)

:D :D :D

Robnjo 05-11-2007 08:53 PM

so pure water is distilled? :?

Mr.Todd 05-17-2007 03:28 AM

Yes,

In most cases distilled water is the closest you can get to pure water.
Reverse Osmosis (RO) is another process that gets you very close as well. However, distillation is preferred in the chemical sciences because it has much less change of contamination than filtration processes.

:D

Mr.Todd 05-17-2007 03:43 AM

Don't get me wrong, RO units like these:

http://www.drsfostersmith.com/produc...?N=2004+113773

are great to use for aquariums, distillation takes much more energy and is kind of a pain...

But for your purposes I would calibrate to some grocery store distilled water.

Personally,

I don't think that color matching tests are very precise at all. There are so many factors that could contribute to how dark or what color you think water in a test tube is...

The important part is that the tests are giving us a general idea of the water conditions. It is the same with any other instrument...

With pH and fish you are mainly looking for consistency within the desired range for the particular fish species. If you are a little acidic or a little basic on your water its not going to stress you fish as much a pH spikes will...

Hope this helps... :P :P :P

caferacermike 05-17-2007 09:46 AM

I wouldn't.


Calibrating your PH pen will need to be done using known calibration fluids. They are cheap. You can buy them from Dr. Fosters and Smith, Marine Depot or your LFS. They come in 7.0 and 10.0. You first calibrate to 7.0 and then calibrate to 10.0. The packets can be folded over and stored in the fridge. That is the only accurate method.

using distilled water does not guarantee anything. Who knows what method was used, when, did the package leach any chemicals, was the water ran back through a carbon filter/mineral filter to add taste to it, etc...... Basically it is an unknown source.

Now we all know why you get what you pay for. After the shipping costs, initial headaches of no instructions, and other similar problems it probably does not seem like such a good deal anymore. Personally for $85 I would have bought a PinPoint scientific PH monitor with a probe that can be left in the tank at all times.

Robnjo 05-18-2007 05:03 AM

Its all sorted now, i took it to my Pool guy and he used the pH stuff...7.0. He said it was way out.


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