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TDS PEN

Lee iley

Member
Joined
19 Aug 2018
Messages
383
Location
Preston
Hi guys,

Just got a prozor TDS and EC test meter
From Amazon only 10 pound. Just tested my water straight from the tap and it's reading 155 TDS. Do I have to buy a solution for this pen to dip into every so often if so how often do I do this. What kind of solution is it as nothing is said in the manual.

Thanks lee
 
Depending on the TDS meter you can get different solutions to allow calibration.

I have a relatively good meter (HM digital COM 100) but I had a few cheapy ones from Amazon before. The HM TDS3 I got was fine but the fake one (was called Yakamoz LCD Digital TDS3) but was terrible.
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I got readings from about 120 to 450 from the standard 342 solution (the real TDS3 was +/- 10)

Not really needed though
 
In this case for what you use it for the acuracy and or conversions you can make of it are of minor importancy. Example if you use it for reference point to know when it's time for water change, than what the number represents is not much of use, only thing you want to know is "How much higher are we from the starting point." If this is for example starting point 120µS and do a water change at 180µS. Than even without calibration you still have you're 60 µS. That's all you want to know... I guess. Since there aint much other use for it in the aqaurium hobby. Only an indicator of solids accumulated, what ever they are..

Calibration if possible for accurate reading is more important when you use it to determine the amount of ferts you want to add. Example in horticulture it can be used for that and than the bottle of fert can say adding X ml/l = averagely X µS depending on the water source. And the fert solution is best at 180 µS for this type of crop, than you first read the starting point of the water source and determine from that starting point how much ferts need to be added not to exceed the recomended EC or add to less for the crop you like to grow. Since adding to much or to less can result in growth inhibition.
 
So would my pen need the solution to recalibrate? Thanks for the reply guys
 
Ok i understand obviously you measure for TDS that is what the thing is all about.. Let me put the question this way.

What is your idea of doing with the numbers you get from this meter?

Please don't get me wrong, if you don't know what TDS actualy is about (read/watch back several previous replies), than why buy it in the first place?

And than what good is any accuracy?

Fisrtly figur this out before you worry about spending more money on calibrating.

Anyway, calibrating an TDS/EC meter you should calibrate closest to the desired value that is best for what you are measuring for. And than you need to know what you are measuring for. Than once you know this there are several different calibration fluids you can choose from.. :)
 
Ok i understand obviously you measure for TDS that is what the thing is all about.. Let me put the question this way.

What is your idea of doing with the numbers you get from this meter?

Please don't get me wrong, if you don't know what TDS actualy is about (read/watch back several previous replies), than why buy it in the first place?

And than what good is any accuracy?

Fisrtly figur this out before you worry about spending more money on calibrating.

Anyway, calibrating an TDS/EC meter you should calibrate closest to the desired value that is best for what you are measuring for. And than you need to know what you are measuring for. Than once you know this there are several different calibration fluids you can choose from.. :)
I got the pen to measure the tds straight from my tap and also to measure tds out of my tank. To see how different it was from my water report. I am loosing cherry shrimp every day at the minute. So I wanted to see if my TDS is high enough and if not what I can do to increase it.

Thanks lee
 
Hi all, All TDS meters are <"really conductivity meters">, so the calibration standards are in "microS".

You can get calibration solutions for them, the best one for general use is "1411", or <"you can make your own">.

cheers Darrel
Hi Darrel on the pen I got I can change it from micros to ppm and when I measured it straight from my tap today it came out as 155 ppm. Tds that is. I think I am correct.

The is lee
 
Is there a general rule about how often one should calibrate a TDS meter (in case you want to keep it accurate)? How can you check if the meter is accurate? My tap water gives a lot (100-150 microS/cm) higher reading than some time ago, and I don't know if that's real or is it the meter. On the other hand I look at the difference (now keeping the fry tank as close to tap as possible) as zozo mentioned so 100% accuracy is not that important I guess.
 
Is there a general rule about how often one should calibrate a TDS meter (in case you want to keep it accurate)? How can you check if the meter is accurate? My tap water gives a lot (100-150 microS/cm) higher reading than some time ago, and I don't know if that's real or is it the meter. On the other hand I look at the difference (now keeping the fry tank as close to tap as possible) as zozo mentioned so 100% accuracy is not that important I guess.
I would like to know this also how often we need to recalibrate. Or even if I need to recalibrate my pen.
 
Lee, this may or may not help you but this is how I use mine.
My tap is consistently around an INDICATED 50ppm, except for when the drought was biting, it has now returned to normal levels.
At waterchange day my tank TDS is around 170. I change 60% with 50ppm tap which resets tank to around 95 TDS, give or take. I then add a bit of GH and KH. Then using APF ferts and following their guidelines, each of the three doses of NPK adds around an INDICATED 18ppm x 3, the trace x 3 adds a bit more. By waterchange day I'm back to my 170 ish TDS from GH, KH and ferts and do a reset with my 60% tap at 50ppm back to my around 95 ppm. This has worked consistently for me and is fairly predictable. What I will say re. TDS pens is that I have a cheap, non adjustable one and a more expensive calibratable one and I found that following repeated tests of the SAME WATER, the cheap one was more consistent and as zozo has said, actual figures aren't that important but it gives a guide to what's happening. Can't help with the shrimp, though, sorry. I don't keep them.
 
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zozo mentioned so 100% accuracy is not that important I guess.

No it realy isn't when you do not know what you are measuring.. As said above it is a Conductivity meter and there are numerous substances that increasy conductivity and these are the Total Dissolved Solids all under the same umbrella..

All you want to know is how far did it rise above your starting point. Your starting point is Water change day with fresh water in the tank.. Than after that, fish and plants secret waste products into the water containing solids. Maybe you add ferts on a daily basis, this adds solids. Water evaporizes but the solids don't they stay in the tank, but than you top the tank of again with fresh water adding more solids. Thus conductivity rises and the EC meter can tell you when it is time for a water change. The accuracy of the numbers isn't drasticaly important even if its off for a few mili siemens.

No what is EC calibration and how does it work? The device is electronic and has an acuracy of maybe 2%. This means if you calibrate at a certain value lets say for convenience 1000 and press the hold button. Than the meter is most accurate at 1000.. Now you put the meter in another solution that read 1800. Than the acuracy is 2% of 800 = 16 off either up or down. If you know what you are measuring for with intentionaly adding solids and you need this rather precise and 1800 is your desired end point, obviously you shouldn't calibrate on 1000 but rather closer to the 1800 to get more acurate data. This because you know what you are adding and want to know how much you did add.

In case you don't know what is added and you have to take that as it comes, than you can sufice with knowing am i Low or am i High.. The 2% inacuracy is not of life threatening importancy..

But simply put, you could calibrated it on your set end point in the tank water. :) But than the reading again is most inacurate when you measure your starting point, since you go all the way down and have to take 2% inacuracy in acount. Since lowest number is the safest, makes inacurace even less important. :)

You see? there always will be a factory set % inacuracy no mater where you calibrate. The further away you measure from the calibration to more inacurate the reading.

Than if you are dead set on calibrating for your own peace of mind, calibrate somewhere in the middle of your set lowest and set highest. :thumbup:
 
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I might add, there are different TDS meters on the market it depends on the make and the use.. Some have a hardcoded electronic calibration point to reset it back when its off. But than the manual says so and prescribes what solution to use. But these are the more professional and more expensive meters. If the manual doesn't say so, it has a hold button and a multitude of calibration ranges.

Calibration fluid, can also tell you that the probe is dirty when the reading is off, than it needs cleaning and recalibration. But it shouldn't, cleaning it after each use prevents it getting dirty. Rinse it off with demi water.. That should read 0 btw.

That's also a way to check up on its acuracy, calibrate it at a high point and put it back in demi water. If it doesn't read 0 than you know its % deviation. :)
 
Lee, this may or may not help you but this is how I use mine.
My tap is consistently around an INDICATED 50ppm, except for when the drought was biting, it has now returned to normal levels.
At waterchange day my tank TDS is around 170. I change 60% with 50ppm tap which resets tank to around 95 TDS, give or take. I then add a bit of GH and KH. Then using APF ferts and following their guidelines, each of the three doses of NPK adds around an INDICATED 18ppm x 3, the trace x 3 adds a bit more. By waterchange day I'm back to my 170 ish TDS from GH, KH and ferts and do a reset with my 60% tap at 50ppm back to my around 95 ppm. This has worked consistently for me and is fairly predictable. What I will say re. TDS pens is that I have a cheap, non adjustable one and a more expensive calibratable one and I found that following repeated tests of the SAME WATER, the cheap one was more consistent and as zozo has said, actual figures aren't that important but it gives a guide to what's happening. Can't help with the shrimp, though, sorry. I don't keep them.
Thanks for that what do you use to add GH and kH into tour tank.

Cheers Lee
 
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