# Digital test kits



## thaerin (Dec 12, 2004)

All right, I admit it. For the life of me (or rather, my fishes) I cannot accurately read those bloody test kits. The eye doctor says I'm not color blind but I wonder sometimes. Every time I test my water then have the LFS test it for me, I'm not even close to what they have. I thought my pH was off the scale (8.1), they said it was 7.2. I have no idea if it's staying constant and I don't like it.

So for the sake of my sanity, I'm going to get digital test kits for what I can. First off will be the pH tester, although if anyone can recommend a digital test kit to measure most of the needed tings for an aquarium, that'd be grand. 
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=58191&item=7500573870&rd=1
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=20756&item=4365394964&rd=1
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=58191&item=3879891738&rd=1

Couple of options I've found. Preferences?


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## pineapple (May 4, 2004)

Good luck. I would advise you try another source rather than the one you linked above. That person has too much negative feedback. The Milwaukee pH meters are reliable. Hannah are not too bad either, but they don't seem to last as long IME.

Try one of our sponsors.

Or Aquatic Eco-Systems for example.

Andrew Cribb


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## glenhead (Jan 29, 2005)

I have the Hanna Checker 1 from proaquatica. Good vendor, instant shipping. The pen has worked well, though it does take it 20-30 seconds to settle on a big pH difference (3+ points).

If you do get a pH meter, you MUST get a pair of calibration solutions (called standard buffers) for it. pH7 checks one side, and choose the direction that your tanks go most - pH4 for more acidic tanks, pH10 for more alkaline. The Checker from proquatica comes with three little capsules of standard buffer powder (4, 7 and 10) to make 20ml (be sure to use distilled water to create them - I didn't on the first go-around) for initial calibration. I trusted that the calibration would last a long time, and was horrified when I took a sample to the LFS and found out that the water that my pH meter said was 6.5 was actually 5.3! Both of the calibration screws were off by over 1/2 point. Lesson learned!

I got a set of standard buffers from a laboratory supply firm (I'll post another item in this thread with the address) and paid $23 total (with shipping) for 500ml of 7 and 4. I bought a couple of 29 cent 10ml plastic test tubes at a local science-fair shop, and fill them about 1/4 full to calibrate. I calibrate my pen at least once a week, and use it daily. It has settled down to where it never drifts by more than a few hundredths in a week.

HTH


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## Laith (Sep 4, 2004)

thaerin said:


> ... I thought my pH was off the scale (8.1), they said it was 7.2. I have no idea if it's staying constant and I don't like it....


By the way, the one parameter that cannot be tested by your lfs is the pH unless they come to where your tank is set up. By the time you get the water sample to them the pH will have changed...

But I agree with you re electronic testers. When I get rich, I'm going to get one of those electronic colorimeters to measure everything! :smile:


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## gnatster (Mar 6, 2004)

I've had a Hanna unit for 7+ years. Takes about 30 sec to get an accurate reading. I calibrate it about every 2 weeks and it reads within 0.1 of my Milwaukee controller. Mine was purchased at a local hydroponics shop for about $29.


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## thaerin (Dec 12, 2004)

Even if it's in a sealed Ziploc bag and tested at the store less than 2 miles from my house?



Laith said:


> By the way, the one parameter that cannot be tested by your lfs is the pH unless they come to where your tank is set up. By the time you get the water sample to them the pH will have changed...
> 
> But I agree with you re electronic testers. When I get rich, I'm going to get one of those electronic colorimeters to measure everything! :smile:


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## JanS (Apr 14, 2004)

I picked up the Milwaukee Smart pH portable meter for $25 in a mass buy, and it's been very quick and accurate.


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## thaerin (Dec 12, 2004)

how do you store a Hanna pH meter when not in use? Any need for special liquids or something?


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## glenhead (Jan 29, 2005)

The directions with the Checker say to store it with the probe wet, preferably in probe-storage solution. The tip of it stays pretty wet if you don't shake it, and the little cap that comes with it holds the water well - I just put the cap back on with the probe wet. I've seen several discussions where people have said it really doesn't matter with the inexpensive probes - the really expensive exotic metal ones are the ones that need fancy protection. Since I got the standard buffer solutions and have been calibrating mine regularly, it's never off by more than .03 in two weeks. I keep it on top of my tank.

One other weird thing. The tester loses its mind when my All-Glass 110W compact fluorescent fixture is on. With the lights on, it says the pH is below 5! Switch the lights off, and it reads correctly immediately. The normal fluorescent fixtures on the other tanks don't have any effect, but the CF fixture freaks it out. Something to watch for...


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## thaerin (Dec 12, 2004)

Does the temp change with the compact on? I noticed soem more expensive checkers mentioned something about correcting for temperature when teting pH.

Anyway, so the Hanna works well but you just need to make sure to calibrate it every few weeks?



glenhead said:


> One other weird thing. The tester loses its mind when my All-Glass 110W compact fluorescent fixture is on. With the lights on, it says the pH is below 5! Switch the lights off, and it reads correctly immediately. The normal fluorescent fixtures on the other tanks don't have any effect, but the CF fixture freaks it out. Something to watch for...


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## titan97 (Feb 14, 2005)

Digital pH meters don't actually check the pH. Instead they check the mV potential between 2 leads, usually platinum or some other metal. The cheap, pocket kind usually do not need to stay wet when not in use. It is the more expensive, glass-bulb-style ones that need to keep the glass moist. Failure to do this will dry out the pores in the glass and make pH/mV reading erratic. The ones I use here in my lab for testing DI water and other process waters costs upwards of US$300 along with a several hundred dollar meter to go with it. These obviously are overkill for us aquarists. 
The pocket pH meters can be fairly good. Just be sure to change the batteries often and definitely keep fresh calibration solution handy. But remember, once you use the solution, it is considered contaminated and should be disposed of. I would never reuse my calibration solutions again with a meter like the Hannas, etc. You might want to look at a chemical supply store for the solutions on the cheap. I think Red Bird and VWR Scientific sell to the public.

-Dustin


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## titan97 (Feb 14, 2005)

In all that rambling above, I completely forgot my point. Since pH meters actually measure mV potential, any source of high voltage will sway the reading. A ballast for a CF fixture certainly would fit the bill nicely. Be sure to remove as much magnetic/electric noise from the vicinity of the meter to obtain good readings.
Also, I happen to find a Hanna meter in with my maintenance crew's equipment. It has a small glass electrode, yet there is no good way to keep it wet. I would recommend that for maximum accuracy, it should be kept in a small container filled with spent buffer. I personally use the 4.0 buffer because it inhibits bacteria growth better than the 7.0/10.0. My testing process would then go like this:

1: Remove tester from storage solution and rinse in clean water.
2: Pour new calibration solutions from my unused bottle and calibrate my tester (I would do this every other time).
3: Turn off my lights and test the aquarium water.
4: Place my tester in the container with the new storage solution (which is made from the freshly used buffers).

-Dustin


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## MatPat (Mar 22, 2004)

I have the Hanna 98129 combo meter. It checks the pH, Temp, EC and TDS. It does compensate for temperature when doing the readings. The EC and TDS aren't really necessary unless you are using RO/DI water or breeding soft water fish. Did you get that DI unit yet?

You do need to purchase a solution to clean the probe, as well as solutions for calibrating the pH and conductivity. 

Thanks for the storage tip on the probe Dustin. I have been using spent 7.0 solution for storage but will use the 4.0 from now on. I didn't give any thought to bacterial growth.


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## titan97 (Feb 14, 2005)

No problem Matt. As far as temperature correction goes, most probes are set to use the pH curve at 20C to 25C. This corresponds to 68F and 77F. Even if you are outside of this range, the variance due to temperature is around 0.1 of pH for every 20F difference. For our purposes, it is probably insignificant.

-Dustin


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## glenhead (Jan 29, 2005)

Wow, Dustin, thanks for the complete info on the probes. Now I understand why it freaks out with the CF ballast. You also clarified the wet/dry storage question. I'll see what it'd take to just store my pen in the 4.01 test solution - I didn't know about the bacteria potential.

I got the standard buffer solution from Omega Engineering, at $5 per 475ml bottle. I guess I mis-remembered what I spent - cheaper than I remembered! Link to the buffer page follows:

Omega Engineering standard pH buffer solutions

(Don't listen, Dustin...) I'm a cheap old bass, and frequently use the little bit of test solution more than once (though I don't remember using any more than three times). I've checked its accuracy and so far, knock wood, it's been dead on. I figure that for aquarium purposes it's pretty danged close.


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## titan97 (Feb 14, 2005)

Good info Glen. The price seems about right for that size. Purchasing a gallon may be more cost effective, but the buffer might decompose somewhat after the "1 year shelf life" had expired. In my experience, the buffers last a long time, well past the 1 year listed. I've kept buffers for maybe 3 years before they get used up. 
And yes, you can reuse your buffers. They won't drift much if they are covered. You want to avoid adding or removing water to them to change their concentration. Evaporation is a killer in this case. I know that they are called "buffers" and that they are supposed to resist pH changes, but look at our aquariums with our carbonate buffers and tell me that they never change over time. In the interest of maximum accuracy, I suggest changing your buffers each time. In the interest of cost savings, go ahead and reuse them, just be careful not to change their concentrations.

-Dustin


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