# Cheap ph pen



## D9Vin (May 12, 2011)

I am thinking about getting a cheap ph meter off eBay, wondering if anyone has used one. I am thinking that since you can calibrate it, it should be okay right? I should be able to calibrate it in distilled water right?


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## neilshieh (Jun 24, 2010)

You could give it a shot and tell us! But if you get what you pay for as a rule of thumb.


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## D9Vin (May 12, 2011)

I am definitely a believer in you get what you pay for. But I am also cheap...


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## Bert H (Mar 2, 2004)

You can't calibrate a pH meter using distilled water. You need a solution of a known pH in order to do that.


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## D9Vin (May 12, 2011)

I was kind of hoping that distilled water would have a ph of 7. How would I go about calibrating it?


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## AQUANZ (Apr 30, 2011)

Most of the ph pens on ebay come with calibrating fluid or powder to mix up. I have a couple of the cheap yellowones off there and they are pretty darn accurate.


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## niko (Jan 28, 2004)

Do not waste your money.

Calibrating or not, cheap or not - any pH pen is trash. Even if you calibrate the thing with 2 different solutions before every single test you do they still show questionable values.

I've used them professionaly long enough to know. Save your money. You don't really need to know your pH that bad, trust me. You can run a planted tank using commons sense instead of chasing numbers.

--Nikolay


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## D9Vin (May 12, 2011)

The reason I am looking into them is I am restarting a tank and I was considering doing it softwater, using peat to soften, but I wanted to experiment with the effectiveness of peat at lowering hardness and ph.


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## niko (Jan 28, 2004)

Peat is very effective but for a very short time. Two weeks tops.

If you take a 5 gallon bucket, stuff it with peat to the top, and make a hole on the bottom you can instantly make water that is pH of 5. This water will be light brown. Like tea. You just fill the peat bucket with water and let it drain into another bucket. 

Adding this water to a tank will not change the pH permanently.

If you actually add the peat to the tank it will provide acidic substrate but it will not change the pH of the tank water. This acidity of the peat disappears after about 2 weeks.

You can find a pH meter useful only if you are looking at a trend. For example check your tap water. Say the meter shows pH= 7.5. It does not matter if the number is true or not. Then check the acidic peat tea-colored water. It will show pH that is lower. Maybe pH 5.5. At this point you do not know your pH exactly but you can confidently say the peat water is very acidic compared to the tap water. Use this trend approach if you want, but stay away from chasing actual numbers.

--Nikolay


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## bsmith (Dec 13, 2006)

Did you get the yellow pen from eBay? I actually posted the same question over at TPT and have yet to get a response. 

I purchased a Hanna Primo TDS (EC) meter years ago for ~$15 and it has been wonderful and doesn't require calibration that often at all.


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## niko (Jan 28, 2004)

A TDS meter is a very simple device. Just be aware that most aquarium lights emit an electromagnetic field that will make the TDS meter show much higher readings. Always check the TDS by putting aquarium water in a clean plastic cup and step away from the aquarium. 

A pH meter is so finicky that for our purposes it basically useless unless you are looking at broad trends. - "Aha! pH is increasing!" "Aha! It's decreasing!". 

--Nikolay


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