$25 ph/alk reader do u think it will work

[cpaulino]

So I was wondering I has used some products in my reef used for horticulture. This device measures ph/alk do any of u guys know if this could monitor water and soil.

I did not put the website I was not sure if I would get flagged

But more. Than anything it would be neat to instantly monitor ph/alk

[celamb89]

sounds interesting, dont have an answer but would like to know!

[bertoni]

It's a pH meter for soil. It won't measure alkalinity, and I don't think it'd work at all in saltwater.

[cpaulino]

Well I am just curious to know. The ad exemplifies that it reads acidity and alkalinity. I have ph probes. But u never know what work in our hobby

[cpaulino]

Well this is the site they have regular ph and tds meters

http://www.sunlightsupply.com/c-639-...solutions.aspx

[bertoni]

Sorry, I should have said it won't measure alkalinity in water. I have no idea what alkalinity in soil even means.

The pH meters intended for liquids probably are okay, although the TDS meter likely doesn't read high enough to measure saltwater. It likely would be fine for checking RO and RO/DI filters.

[cpaulino]

Well they seem to use a lot of the measuring devices we use just saw the other day. it woild be a heck of a less expensive meter than a hanna. But hanna is really precise on the other hand given when used properly

[Randy Holmes-Farley]

It is just a cheap pH meter. Their use of the term alkalinity is slightly different from ours. They just mean whether the pH is alkaline (above 7) or acid (below 7).

I would avoid any pH meter unless it specifically says it has two point calibration. This one did not say. Some use none or 1 point, which is inadequately accurate for our purposes.

[cpaulino]

That is what I thought. I know I have to calibrate the ph probes using ph regent solution

[JTL]

Originally Posted by Randy Holmes-Farley

It is just a cheap pH meter. Their use of the term alkalinity is slightly different from ours. They just mean whether the pH is alkaline (above 7) or acid (below 7).

I would avoid any pH meter unless it specifically says it has two point calibration. This one did not say. Some use none or 1 point, which is inadequately accurate for our purposes.

Out of curiousity why is the 2 point so important? I have tried both and they seem to have the same readings, although the one point (cheap Milwaukee) will not hold calibration, but the Hanna (2 point) didn't last long either.

[bertoni]

The pH meter works by doing linear interpolation, so it needs to have two measurements to define a line. With only one, it must guess at the slope. The guess can be good or bad.

[Randy Holmes-Farley]

More particularly, there is a "zero point" at pH 7 and then a theoretical slope between actual pH and the electrical measurement a pH probe makes. pH meters with one point calibration only set the "zero point" at pH 7. They assume the theoretical slope is accurate. That is often close to true for a brand new probe, but over time things happen to them which lowers that slope and the theoretical assumption is no longer accurate. In that case, the farther you are from pH 7 (up or down), the less accurate the measurement becomes (in absolute pH number terms)

These have more:


Measuring pH with a Meter
http://www.advancedaquarist.com/issues/feb2004/chem.htm

A Comparison of pH Calibration Buffers
http://reefkeeping.com/issues/2005-02/rhf/index.htm

[JTL]

Thanks for the information, now I wonder if my cheapo meter is even close to accurate.

[bertoni]

Thanks for the details, Randy!

[Randy Holmes-Farley]

Originally Posted by JTL

Thanks for the information, now I wonder if my cheapo meter is even close to accurate.

It is easy enough to check out with commercial standards. Use pH 7 and 10 for that purpose.