digital meters..

[JasonC]

Hi,

I'm looking for recommendations on decent probe meters for water parameters. I think ideally I would like to at least read pH, Temp, TDS. How are the 6-in-1 meters that are always on ebay being sold by Chinese vendors? Junk, or at least halfway decent? Any other reasonable alternatives under $100?

Thanks!

Jason

 

[slimbolen99]

I was just going to post the same question. a friend of mine has a tds meter and a ph meter. I will ask him what he got because he's big into plecos.

 

[CopabX]

The Hanna line is pretty good but they need the calibration buffers. Once they're calibrated they're fine but a little pricey after 2 buffers and the meter. try getting them on amazon in one of those bundle deals for about $55

 

[ste12000]

Yep, its a case of you get what you pay for. In my opinion its worth the extra to buy a Hanna PH meter, mine measures PH and temp.. The cheaper PH meters are calibrated by a screw and are almost impossible to get anywhere approaching a accurate reading.

I use a cheap TDS meter(Hong kong special from ebay) this has worked fine with no problems.

 

[jaafaman]

I'm going on 13 years' service from a Hanna Pinpoint Conductivity Meter with only small, annual "recalibrations". But it is the second probe used on this meter to be totally honest...

 

[dw1305]

Hi all,
I like Hanna meters as well. Conductivity meters are much easier to service and calibrate than pH meters, they work by passing an electric current between 2 electrodes and measuring the amount of current that arrives, so there is little to go wrong. You can also make up your own calibration fluid without any problem (or buy one, but this is much more expensive).

You need a "low range meter" (0 - 999microS is the highest range that is useful). The best bet is to make your own calibration solution from KCl (potassium chloride). The usual calibration solution is 0.01M KCl which has a conductivity of 1411 microS at 25oC. Conductivity is approximately linear so you can go where you like from there.

7.46g of KCl in 1000cm3 H2O = 0.1 Molar sol., 100cm3 of 0.1M KCl in 1000cm3 = 0.01M and 1411microS. 5cm3 of 0.1M in 100cm3 is approx. 755 MicroS etc.

I usually ignore pH and just dip the conductivity meter in, as long as I get less than 200microS I'm happy.

If you do want pH as well, as Steve says you need a reasonably good, dedicated meter and pH4 and pH7 buffers. You also need to buffer the meter every time you use it, and ensure that the electrode is stored in the correct manner etc.

You can make the buffers, but not realistically unless you have access to a chemistry lab. and most labs buy them in.

cheers Darrel

 

[Mike Wise]

I've been using a Hanna HI 98129 combination pH, µS, ppm, °C/°F waterproof meter for about 5 years now. It even went through a 4 week trip to the Amazon with flying colors. Yes, it needs calibration periodically (all meter do if you want any kind of accuracy), but it isn't hard to do. Probes are replaceable (not needed yet) and batteries last a long time (just replaced mine for the first time). A bit expensive, but definitely you get what you pay for.

 

[gerald]

I have an IQ-120 pH meter that uses an "ISFET" chip rather than a glass membrane electrode. ISFET chip meters seem to do better in very low conductivity water where memebrane-type meters are slow to respond. Also you store it dry and it requires far less maintenance than traditional pH probes. I paid about $180 several years ago; they cost about $200 now from Ben Meadows Co. Replacement electrode is $70 - I need to replace mine now for the first time, after 3-4 yrs. Hold it AWAY from light ballasts or other electric devices when taking a measurement. I get a different reading using it IN the aquarium (with lights and filter running) vs in a cup of water held away from the tank. It's really nice for field use too.

Mike - Did your Hannah Hi 98129 have any trouble getting steady pH readings in ultra-soft Amazon waters?

 

[Mike Wise]

Mike - Did your Hannah Hi 98129 have any trouble getting steady pH readings in ultra-soft Amazon waters?

I was measuring about a liter in a plastic specimen cup. I didn't really notice any difference from using it at home, where I have soft tap water. It's not instantaneous, but just as fast as using a liquid pH test kit.

 

[JasonC]

I've been using a Hanna HI 98129 combination pH, µS, ppm, °C/°F waterproof meter for about 5 years now.

This looks like exactly what I am looking for. Little over what I was hoping to pay, but I guess it would be worth it if I keep getting deeper into the hobby. So when I purchase it, I am going to need to buy/make 4.0pH and 7.0pH calibration fluid, as well as a buffer fluid for the probes, correct? Is there anything else on the shopping list I should add for this?

Thanks!

 

[dw1305]

Hi all,
You will need to buy the pH4 and pH7 buffers and have some de-ionized water, these aren't a thing you can make easily. You need to be very careful that you store the probe in the conditions that Hanna recommends. When you want to use the meter, you need to turn it on (probe in the de-ionized water) and wait for at least 5 minutes. Ideally you want to have the tank water, buffers and de-ionized all about the same temperature, even if the meter has temperature compensation. You dip the meter in the pH4 buffer, wait for at least a minute and adjust the meter to read pH4, you may find that you can store this reading as "cal. 1", you then need to sluice the probe in the de-ionized and then put it in the pH7 buffer, you will probably find that you won't get a reading of exactly pH7, you don't need to worry about this, as long as it is reasonably close (pH6.9 - pH7.1 range), this is due to the nature of the pH scale.
If the meter reads along way out at pH7 you need to go throught he pH4 buffering again. Once you have readings of pH4 and pH7, you can test your tank water, the nearer the water is to pH7 the longer the meter will take to give a stable reading.

The conductivity meter probe is a lot more robust, and you don't need to calibrate it every time you use it.

cheers Darrel

 

[CopabX]

It may also be worth it to get some resealable containers for the buffers so you can re-use it and not contaminate the source bottle. Try to get graduated ones so that you can measure the evaporation of the buffers and compensate.

 

[Mike Wise]

Get the e.c. test standard, too. Some recommend the probe cleaning solution, but I never use it. Just clean the probe with clean water before storing. I recommend buying boxes of individualn test standard packets instead of a bottle. There is less possibility of contamination. Packets cost more, but could be less expensive if a bottle is contaminated.

 

[Mike Wise]

My Hana meter is self-calibrating. Once you put it in the solution, the meter calibrates itself.

 

[tjudy]

Storage solution for pH probes is not plain ionized water. According to the tech at Hanna it is the same solution as the pH 4 calibration solution. Storage solution is important if you are not using your meter every other day or so. What I do is calibrate, use the meter and then fill the pH electrode cup inside the cap with the pH 4 calibration solution before capping the meter.

 

[Mike Wise]

Great to know, Ted. I'll be saving the pH 4 solution from now on.

 

[JasonC]

Ha. Seems that these digital meters are a lot more complex than I was expecting. Guess if I wanted "dip-and-read" I should have gone to test strips and accepted the inaccuracy of them. Probably be at least another month or so before I can splurge on this. I'm sure I'll have questions then.

 

[dw1305]

Hi all,

Seems that these digital meters are a lot more complex than I was expecting. Guess if I wanted "dip-and-read"

You can do this with a conductivity meter. They are robust and easy to use. This is why I dip one of these in the tank occasionally. To get a genuine pH reading is time consuming, but if you don't have many salts or much buffering in the water you know that you can lower the pH with peat, Oak leaves etc.

cheers Darrel

 

[JasonC]

I did know about the peat and oak... actually just came inside from snipping a few branches to dry out. The peat, well, I am still trying to figure out a way to sneak a bale in the house w/out my better half flipping her lid ;P.

My tap water tends to be relatively soft... 3 deg. ish of kH.. somewhere between oh 5 and 8 deg. gH, and neutral .. 7ish pH fresh out of the tap. Is there any real reason to monitor pH to the extreme of this pH meter, or should I be good with just putting some oak leaf and twig litter in the tank? I imagine the scientifically accurate measurement of pH is more nessisary for the more sensitive species?

Also, if you dont mind, i am not quite sure I understand conductivity and how it relates to fish health? I understand pH, hardness, and obviously temperature, but what are the ramifications of too high or too low conductivity?

Thanks!

 

[Mike Wise]

For apistos, all pH/ec/ppm meters are more precise than needed. The same can be said for most of the chemical test that are more accurate that +/- 0.2 pH. The advantage of a meter is that it os less expensive over time than chemical tests. The posts here make calibration more complex, expensive, and necessary than it truly is. Calculate the cost/test with a meter compared to chem/test strips and it becomes obvious. You'll be willing to test your tanks more often with a meter than a chemical test because it's less expensive and time consuming.

E.C. is a measure of conductive ions dissolved in water. In soft water, hardness and e.c. are roughly the same - not so in hard water. In apistos, like many other softwater fish, high e.c. it can retard the urge to spawn and adversely affect development of eggs.