D I C K Smith digital PH meter

[D.J]

Hi Proteus,
Just bought the ph tester on Sun, but what worries me is that, when I used my Sera manual test kit, the result is 6.8 or close to 7.0, but as soon as I used DSE it comes as 7.23.
I even bought the laboratory grade buffer just to be sure and it is spot on @7.0, what could be the problem there? :?
I know that you allready have one of your mate in the lab to have it tested, and the results was accurate, do you think I may have gotten a bad stock? :x , eventhough when I used the lab grade buffer it is ok?!
Please let me know what you think, as if I did get a faulty product, I may get it exchanged.

Thanks,
Donald.

[Mattzilla]

can you post a picture of the ph tester that you bought???

thanks
matt

[Proteus]

Manual tests can be VERY misleading, if the chemicals are more than 6 months old, they are not very reliable.

Now think about it, the chemicals are in the kit for a few weeks after being packed, then there is the shipping, and however long you store has had it for...

I have just had a problem with my Ammonia and Nitrates kits, I was getting funky readings that werent even on the colour chart, so i went, got some fresh chemicals, and 1 hour later, get accurate results (or at least on the scale).

You also have to stir the probe around in the water to ensure good contact with the water.

I would be of the opinion that your Sera kit needs new chemicals (ps, if you want a REALLY GOOD maunal kit, get a JBL one, they are simply the best test kit around) I have sent some kits to the U.S. and they drool over how easy they are to use, and obtain a result.

[Proteus]

(image)

http://www.dse.com.au/isroot/dse/images/products/q1416.jpg

[D.J]

Thanks for the reply, Proteus.

I tested the meter again on various water: it gave a reading of 7.85 for my tap water, 6.8 for Brita-filtered drinking water, and 8.5 for boiled water :? . This seems a bit erratic to me. I do stir the water until it gives a stabilised reading.

I know Sydney water is very soft and slightly alkaline, but 7.85 seems a bit high to me.

However, I agree with you that my Sera test kit could be expired.

[Proteus]

7.83 is what I get straight from the tap.

if I activate my in-line tap filter after a few minutes to settle it is around the 6.9 to 7.1 region.

as for boiling water, I would suggest not doing that as it may shatter the probe and then the unit it useless... I would think the high reading is due to the sensor not knowing what the heck is going on.

[Proteus]

FYI, as soon as I finished the last post, I filled a glass with water straight from the tap, placed the tester in there, gave it a stir, and took a photo...

pH = 7.81

[Proteus]

ALSO...


Specifications:
Range: 0.00 - 14.00pH
Resolution: 0.01pH
Accuracy: +- 0.02pH
ATC: 0-50 degrees celsius
Battery: 1.4V x 3pcs (A76 type)
Size: 158 x 40 x 34mm
Weight (w/bat.): 90g

I make reference to the ATC information.

ATC: 0-50 degrees celsius

which means the unit will only provide accurate readings up to 50 degrees celcius.

HTH

[D.J]

lol Proteus, I didn't use boiling water. That would definitely mess up the meter :). I meant boiled water that has been cooled down to room temp.

I think it's just due to built-up minerals in my kettle.

[Proteus]

lol... sorry...

yes, kettles do have a thing about changing the composition of the water.

[chrissyoscar]

I just got one of these from D i c k Smiths as well.
I'm not sure if mine has a problem but the readings are all over the place.
I've cleaned it with water then calibrated it but when I went to get a sample from the tank the figures were jumping all over the place.
I can't get a steady reading because any slight movement sends the figures crazy even the water movement in the tank send the figures jumping from 6 to 3 then to 12 back to 6 and so on. What am I doing wrong. I've never used a ph meter before so HELP PLEASE!!!

Oscar

[D.J]

Try to use the supplied buffering solution to calibrate the meter.

[chrissyoscar]

I did use it but the figures just jump everywhere with any slight movement.
Might have a faulty unit :(

[Merrilyn]

Oscar, I've got one of the older type ph meters. In the instructions that came with it, it states to use still water (not moving) so I take a sample of aquarium water in a clean glass and drop the pobe in. Set the glass on a stable surface, then take the reading after 30 seconds. That should work - if not I guess it's faulty.

[kalebjarrod]

Ladyred by "still water" did they mean distilled water?

or STILL water?

[Merrilyn]

Nah - just not moving, as in water flow from a tap or moving water in aquarium. Mine is a dedicated aquarium meter made by Trans Instruments. The other thing it mentions is that the probe should be shaken down - just like you would shake a themometer before you took a persons temperature. (does that make sense?) Also, if, it hasn't been used for a long time and you are getting eratic readings, it should sit in water or calibration solution for 1-2 hours before testing again. Hope this helps.

[Proteus]

ditto to what LadyRed suggested...

put the probe in a still area of the tank, or better still get a glass, and add some tank water to that and let the probe stabilise for a few minutes.

[chrissyoscar]

Thanks for that Ladyred and Proteus.

It's good to know that the unit is okay after all. I had no idea they were so sensitive to movement.

Oscar

[Bad Inferno]

I maybe new to Discus but after 22 years in instrumentation I can help with PH.ORP conductivity etc etc etc.

The PH probe has two electrodes..A glass measuring electrode and a "reference electrode. In our application the glass electrode should be OK and would not suffer coating. The reference electrode is actually a "wick" and wihtin the unit will be a reservoir of kcl solution. This is why the electrode should NOT dry out as the wick dry's out and you loose the electrical connection to the fluid being measured. (Thats why people say shake the electrode in a downward motion to try and get the kcl solution wetting the wick again. Store the unit pointing down will also help.

I have not seen a DSE meter however I assume it has a piece of foam in the lid which contacts the electrode when being stored make sure this foam is wet...best to rinse with distilled water before putting away and between buffers when calibrating. The Glass electrode is very very thin on top so be extreemly careful, never put your fingers on it.

Your meter should NOT change reading when moved in the fluid being tested unless there could be bubbles in solution or a non-homogenius mixture being tested. My $40 handheld unit does not do this

I have had my hand held for at least 10 months and really only needs minor zero adjustment, however every time is within 0.2 ph within the full span 4-10ph. This may seem alot to you however to get something worth 40 bucks with a repeatability of 0.2 from month to month over the entire span of 4-10 pH is great, especially when the electrodes in my unit dry out from lack of use. If you get one make sure you wash in distilled water between dipping in pH buffer solution and your buffers should last along time. Also rinse the electrode in distilled water prior to putting away (needs to be kept moist) and it should serve you well.

http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&category=20756&item=4314478351&rd=1

cheers

[Escher]

I just bought the DSE meter and it's again on special for $66. So far I had no problems.
And it's a beauty; my pH had gone down to 5.00 so the chemical test was useless (outside the range). No wonder one of my fish was stressed!

[weird]

I went out and bought one today, thank you for the information. Will try it out tonight.

[Proteus]

if anyone else is interested in getting one, or thinking about it, say so on here... maybe we can get a further discount for buying several at a time...

like i suggested previously, it is worth a shot.

[lesley]

Hello Proteus,

You could add me to a list of prospective purchasers.

Lesley

[flukes]

add me to the list..
If we can get a few members intrested we might be able to get a cheaper rate. Its worth a shot for all the advertising were giving them. :wink:

[weird]

I got mine replaced today. The first one I got on Monday , was swinging widely and could not be accurately read, and finally the LED got stuck at reading of 1 after 48 hours from purchase. The replacement one I got today, does not flucuate and appears very accurate. If the reading is swinging widely when you put in a cup of water or the supplied buffer, take it back.

[chrissyoscar]

I'm taking mine back. Mine doesn't fluctuate widely anymore but it did when I got it 1 week ago. It still fluctuates for example it will read 6.61 then 6.66 then 6.74 then 6.69 and so on. When I first got it it was swing from 4 to 6 to 12 back to 4 then to 8 you get the idea.

[weird]

Yep I would, I did my testing and calibration at work with the buffer and a guy stuck it in his water to test it.

I have just got home, and tested my 3 tanks at home ( discus tank, community and a small tank of my friends who is overseas) ... 2 of the tanks have high movement of water with bubbles from a sponge filter and an air stone ... even the discus tank has a sponge filter ... with the ph tester I got distinct readings ... that is the tester settled on a particular number quickly and did not flucuate.

[chrissyoscar]

I took my ph tester back to D ick Smith yesterday and swapped it. The new one works much better.
Thanks for the advise Weird73.

Oscar