pH meter better than bottle?

**blahdeblah** · 29th Nov 2011, 08:02 PM

Hi,

Just wondered if anyone uses the electronic pH meters - loads on ebay for around £10-15.

Are they accurate enough for aquarium use, or should I stick with my old liquid drip bottles? I struggle sometimes to define the exact result through the colour chart and want something that will do the job properly.

Are the cheap ebay ones good enough for shrimping?

Cheers,

Mike.

**magpie** · 29th Nov 2011, 10:45 PM

I prefer PH meter to liquid test kit. Accuracy of ph reading from
The ph meter depends whether is the meter well-calibrated. Usually there is a known amount of ph in a bottle that you get to allow you to adjust and calibrate your meter before use.

**RiverAquatics** · 13th Jan 2012, 09:12 AM

I'm fighting the same decision. Hanna Instruments and a few other companies make some very nice devices but with the replacement tips, cleaning solutions, etc., I could buy a lot of tests so I wonder about the value, but for the accuracy, I'm sure they are precise when taken care of properly.

I just but a $9 TDS pen on eBay but to be honest, I'll always question it's accuracy and would feel the same about a pH pen for $15.

I plan to replace the cheap pens, when I use them, at least yearly. I'm sure they can be as good as a basic chemical test but for how long considering the expensive pens have issues like keep the tips clean, calibrated and wet.

I'm sure many use them with good results but don't expect those cheap eBay pens to be like the more expensive brands... but for quick readings and to compare to my chemical tests results, sure. I'll probably get one myself.

**Lux89** · 13th Jan 2012, 06:07 PM

LOL, this is so funny. I was here just to make the same thread as this one. I bought one pH meter on eBay for like 13$ and I'm not sure how accurate it is. Got some normal liquid tester but I hate em, I really am not sure about the colors. Every time I think the color is a different one, and when it clear I'm still not sure if its this one, or if its the other one. I would really like to just use the pH metar. But hmm, are they all the same or do the expensive ones really make a difference?

**blahdeblah** · 13th Jan 2012, 06:17 PM

I got my digital pH pen off ebay......but honestly I had NO idea about what you have to do to them to calibrate and maintain them. You need special calibration liquids in order to calibrate, distilled water to clean them, keep nibs damp, AND they are not accurate after 12 months. Doh!

I think i might be reverting to liquids.........better the devil you know sometimes! Buyer beware..

**RiverAquatics** · 13th Jan 2012, 10:26 PM

The expensive ones with the solutions when well maintained are used often and work well but you really need to learn how to use them and maintain because they degrade quickly without proper care. Calibration is a must. I did some math on a decent muti-test type and supplies for it, the replacement tip alone was $50 US and one could easily spend $200 just to get going.

This will be a long time goal... I have a few hundred chemical tests left before I panic.

I want to get my hands on Saifert brand tests because it's claimed they have colors that are easier to distinguish between, but I've never used that brand.

**Shick Settima** · 17th Feb 2012, 01:44 PM

I'm glad I clicked on this thread as I just ordered one of those ebay pH meter specials myself. One of the yellow ones that are everywhere on there. I figure it's not too expensive and it's better than nothing for now.

**randyl** · 17th Feb 2012, 02:42 PM

Originally Posted by Shick Settima

I'm glad I clicked on this thread as I just ordered one of those ebay pH meter specials myself. One of the yellow ones that are everywhere on there. I figure it's not too expensive and it's better than nothing for now.

I think I have the same one. Something like $11 shipped. Is it any good? Well, short answer is yes.

Here is the long answer : I don't need to know the exact PH. I mean, if it says 6.5 but the real PH is 6.6, so be it. I just want to make sure my water is stable. This cheap PH pen is good for that. I tested it with different water and it reads the same for the same water after at least 5 tries in each water, so I'm happy with it.

The only thing I don't like about it is the speed. It takes a while to get to its "final answer". For example, if I test water with PH 7.5 (my FR tank), then use it in my CRS tank (PH 6.5), it will show something like 7.2 immediately, then 7.1, 7.0, .... until it reaches 6.7, then it will take another 5 seconds to 6.6, then another 5 seconds to 6.5. So it takes 20 to 30 seconds to get a reading sometimes. But it's pretty consistent so I don't complain for this $11 PH pen. I'm thinking to get a more expensive one if it is faster.

To calibrate it? I just go to my LFS and test their water (I got the permission first). This store mark PH on every tank, so I know if my PH pen is okay or not. Again, I never really care the absolute PH, I don't think you can get that with even one that costs $100 because conductivity in water can cause the reading to change. (cheap PH pens test the relative conductivity instead of the H+/OH- concentration)

**Sprae** · 19th Feb 2012, 04:29 AM

I'm looking for a pH and a TDS meter as well. Looks like it's better getting cheap ones as you can easily replace it after 12-months with a brand new one $10 against maintain a $100 meter. And that's if the cheap one don't work. I agree that within 5% range of accuracy is totally acceptable.

**Navanod** · 19th Feb 2012, 01:57 PM

I see many people are having questions with budget pH meters.

As long as it can be calibrated, most pH meter would be fairly accurate. The more expensive ones may give more decimal places and hence are more sensitive, or they may last longer, but on the whole, cheap pH meters are good enough for our purpose. The ones that cannot be calibrated (keeps failing or going off readings) are bad and should be discarded.

About calibrations, it should be done with proper pH buffered solutions of pH 7, 4 and/or 10. Depending on whether your tank is always in the alkaline of acidic pH range, you can do a 2 point calibration with 7 & 4, or 7 & 10. If you want to be very sure, a 3 point calibration with all 3 pH would be ideal.

Beware of using the shop's tank water to calibrate. The shop's written pH may not be very accurate either and may just be a guide on the pH to provide for the fishes in that tank.
Also, that's only a 1 point calibration which is frankly, not accurate at all!

When calibrating, pH 7 is to "zero" the pH meter so it knows exactly what is the amount of conductivity at pH 7. The pH 4 or 10 solution is then needed to make sure that the meter knows how much each increment in conductivity is supposed to increase the pH by. Imagine a graph with voltage as one axis and pH as another. The meter needs to know the gradient or slope of the line from 4 to 7 to 10 in order to translate raw readings into pH.