Australia's Science Forum

One of my teachers has siezed on the brilliant idea that I should be getting, get this, a class set of data loggers so that we can do water testing during our sea shore excursion. (wtih my spare money, at this end of the school year! )She wants me to find one that measures pH, salinity, dissolved and temperature all in one. Does such a single probe exist? And how would it go in sea water?

Do any of you guys use anything like that, and is it useful? One of the other teachers has an opinion that some data loggers do everything for the kids, ie produce a continuous graph, and that leaves the kids with nothing to do using their own brains. I'm in the middle of the two of them.

Please guys, can I have some feedback. Quite apart from the expense, I ned to know if they really worth it for what we are going to do. I mean, we are recording the temp/salinity/O2 of rock pools over a few hours during the middle of the day. Is using a data logger like cracking peanuts with a sledge hammer?

Quite a bit has been posted on this before - we were in the same boat about 12 months ago.

In the end we went for Data Harvest against Vernier but there are many others. Vernier has a much higher sampling rate than Data Harvest which would have been a bonus in retrospect.

No single probe will measure all the things you want to log but a range of probes will. We have 2 different units from the same manufaturer. The smaller 1 has 2 ports but built in temp, db, atmospheric pressure, light % etc. The larger unit has 6 ports but no built in sensors. We use them all the time for water testing and they are simple to use and set up.

We test for pH, dissolved oxygen, water temp, conductivity and log either stand alone or attached to a PC. Times of logging for us vary from doing a quick snapshot to logging our fish tanks for weeks. We also have loads of other probes for motion/speed/distance etc etc.

Visit here: http://www.data-harvest.co.uk/dataloggi ... e_s_g.html

Serrata are the importers we went through.

Also, we used this as a guide (below) when looking at purchasing to help us make the right decision. It has a questionare at the back for you to fill out and compare different manufacturers.

Hope this helps!

We also use data Harvest from Serrata.
We have few extra probes as well such as light sensor, light gates, O2 probe, voltage,motion sensor and prndulum sensor. They dont get used very much, but every now and then some teacher has a brain storm and starts using them again.We have had them for at least 10 years, and we had to send one unit back for a battery change and had to buy 2 new pH probes, as they get used often and dont last for ever.So over all I am happy with it.
Lada

Hi Smiley,

Tell your teacher she is dreaming! No such probe exist, not for school purposes nor for comercial purposes. The closest thing you can get is what Slartibartfast mentioned, which is the data harvest easy sensor which then in turn connects the different probes. Not even in large scale commercial aquaculture do they have one probe that measssures everything, and water quality is of utter importance to Aquaculture. Oh I forgot, all probes are ok to use in sea water, as long as they are properly rinsed after each use, if not they rust!

Sassi

smiley wrote: Please guys, can I have some feedback. Quite apart from the expense, I ned to know if they really worth it for what we are going to do. I mean, we are recording the temp/salinity/O2 of rock pools over a few hours during the middle of the day. Is using a data logger like cracking peanuts with a sledge hammer?

Just saw the last of your question... Our school has had the data harvest loggers for quite some time and the teachers still have massive issues using them, so for that reason we are changing over to verniers go link probes, which are easier to use, the down side is you can only use one probe at a time. Are you only going to use the probes for this one purpose, the rock pools? In that case I would suggest to get some ph-meter, dissolved oxygen meter and temp probe, which are not actually data loggers. They are better, more accurate, plus the kids will have to record the readings and thus need to use their brains more. When I find where I have put it, I shall post a link were you can get these time of meters.

Sassi

Thanks guys!

Richard, I've downloaded that form and will work through it with my HOD.

Sassi, I'm with you. We have a pH meter, a salinity meter, and I'm quite happy to buy a DO meter. My proposal was to set up a testing station, under a shade tent of course, and the cherubs can bring their samples to me and we'll do the tests production-line style.

Mind you, as I originally indicated, the money tree is definitely deciduous, and it's autumn up here.

My Chemistry teacher has just asked me to enlist some help from you guys, as we are at our wit's end!!


We have recently bought 3 Vernier Labquest data loggers with pH probes, and we have 3 older pH meters that operate independently. If we sit them all in the same solution, none of the readings are even close.

I can understand that the pH meters may be old and useless, but the probes for the data loggers are brand new, and the instructions say that for basic operation they do not need to be calibrated.

Has anyone else had similar problems?
I've already made a name for myself arguing with this supplier and am reluctant to approach him again, unless absolutely necessary.

Julie

Now that is interesting indeed Is there a massive difference or does it come down to decimals? If that is the case it could just be a matter of different probes different degrees of accuracy. However if there is a massive difference, then I can only see one resonable explanation, they are not calibrated porperly... have you tried calibrating them? I had that problem with some pH probes of mine, and calibrating them fixed that problem. Are they stored in a solution (K..something), if so are they covered in enough solution or have they been dried out. Drying out affects the accuracy too... And also air bubbles in the probe affects them too...

But then again these are just hypothesis, anyone else got any ideas???

Sassi

Ranges between 7.8 and 10.4.
I guess I'll just have to calibrate, but I was hoping to rely on the calibration that they SAY was done before shipment. The instructions clearly say that calibration is not necessary.

In fact on further reading the instructions, it says that the calibration is automatically loaded when the pH sensor is connected. But if I plug all 3 sensors into the same data logger, I still get 3 different readings.

Oh well, it looks like another phonecall to my friendly (not) supplier. Dammit, I could do without that! Maybe tomorrow.

Julie

Sorry Julie,
A quick aside, Do you have Ian Judd as a teacher at your school??

Ian Judd has just transferred from HT here to HT at Kyogle.

Did you get them all at the same time? Or is some older than others? If same age, get them to send you new ones (that work) ! If different age, tell me are they stored in a solution? If that is the case, most likely they have been dried out at some stage and thus damaged. Try calibrating if that doesn't work there is a possibility that they have been ruined and you problably need a new one :(

I store my electrodes in 0.1M KCl.Keep the pH sensitive membrane wet at all times.
Leave them in distilled water for couple of hours and then try buffer. My pH meters are easy to calibrate, but the probes that come with Data harvest are difficult to calibrate, you have to run the Sensor Configuration program. I have never done that. They seem to keep reasonable accuracy
Sanscha, what are you going to do with your Data harvest probes and sensors? If you wont use them, pass them to us.
Lada

Would love too give them to you, but the change over is gonna be over the next couple of years, although pH sensor will be one of the first one to be replaced. When I find out I will let you know!

We got a new Data Harvest electrode last year which read way over in pH 7 buffer. I tried calibrating using the Sensor Config, but the ADC values were basically all the same for ph 4,7 & 10 so the program wouldn't accept the calibration. I rang the supplier and was interrogated as to why I needed to calibrate a new probe, and told them the problem (it was reading ~14 in anything, even acid solutions). After I sent it back, they agreed that it was faulty and replaced it. New one OK and just for the exercise, I've (successfully) calibrated it.

Hi All
What data loggers are most of you using? We use Harvest loggers without much success!
I need to purchase have descent money in our budget and at the moment it is between Pascoe or Vernier. We will need to use Physics and Agriculture and Bio Stuff and have to use remote as in a field trip situation.
Maureen.

Hi, we just purchased Ezilog, so much easier that the vernier one we had. You can also buy adaptor leads so you can still use your old sensors.

Sorry I have tried to do a Merge but can not get it correct. Please do a search for Data Loggers, their is a very good thread on this. Which help't so many of us. Sorry I was unable to Merge these two posts. "Who uses data Loggers"

Thanks Macca
I will goggle Ezilog!

Ta Sue
I will goggle a few dataloggers and see what I can get! Yeah I'm with you I have never used one so might have to start