# Seneye



## tubamanandy (13 Feb 2014)

A warning:-

Up until very recently I wasn't aware that my Seneye Reef was unable to give me correct PH readings as my KH is always <7 (usually 4-5). Great thanks to a fellow poster for letting me know about this.

As I couldn't find anything about this in their literature when I bought it, I decided to drop them an email a few days ago. Whilst not actually confirming the above, they used every excuse under the sun to say that many electronic meters cannot read PH values in low KH water.

After a couple of emails they asked me what equipment I was using to measure my PH other than the Seneye. I told them it was my Pinpoint PH meter calibrated to PH7 recently and a newish PH test kit. PH meter gave a reading of PH 6.4, test kit about 6.4-6.6 and Seneye meter 7.17.
As soon as I gave them the above information they broke off contact with me and never came back to me.....not exactly inspiring confidence. I still use the meter for temperature & PAR/LUX readings but I'm very reluctant to pay £6/month anymore for slides. Not happy


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## Sacha (13 Feb 2014)

I had pretty much the exact same experience as you mate. They know they've screwed up- I could tell from the way they were acting. 

It really should be made clear before you buy the expensive bit of equipment that it is actually incapable of measuring pH in soft water.


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## flygja (14 Feb 2014)

It's sad that their pH readings don't go lower than 6.4 too. My high-tech tank with CO2 injection and ADA Aquasoil goes lower than that. I stopped buying slides. I just use it for the PAR/lux/kelvin meter really.


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## Sacha (14 Feb 2014)

Like I said in the other thread, for the last two (?) years or so, they have been promising: 

1) a low pH slide 

2) more parameters like nitrate and chlorine. 

All of these things are "coming next quarter". They have been coming next quarter for the last 7 quarters, so I'm not holding out much hope. 

Greg at ADC is my main point of contact because he is in direct contact with the main man at Seneye. We always have a joke about them whenever I go in. He said that he spoke to them frankly, and they said the slide can't measure pH in water of less than KH 7 (which has already been confirmed here). But they also said the new slides will be here in 4 months. 

I'm not going to hold my breath.


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## dw1305 (14 Feb 2014)

Hi all,





tubamanandy said:


> Whilst not actually confirming the above, they used every excuse under the sun to say that many electronic meters cannot read PH values in low KH water.


I'm not making excuses for Seneye, and I wouldn't use their devices even if some-one gave me one, but this is true, pH is a fairly meaningless measurement in very soft water.

cheers Darrel


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## zanguli-ya-zamba (14 Feb 2014)

dw1305 said:


> Hi all,I'm not making excuses for Seneye, and I wouldn't use their devices even if some-one gave me one, but this is true, pH is a fairly meaningless measurement in very soft water.
> 
> cheers Darrel


Hi Darrel, I am quite interested in why is it meaning less to measure ph in very soft water ? As I live in congo and tap water is less than KH 1. I use Mg and Ca to raise it at Kh 5.
Does this mean that my Ph reading are not the real values ? 

cheers expert


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## John P Coates (18 Aug 2014)

Hi folks,

As this thread is entitled quite simply 'Seneye', would this be a suitable place to share our experiences about the seneye range of products?

I have a seneye reef monitor but I don't want to hijack this thread. If necessary, I'll start a new one.

JPC


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## GlassWalker (18 Aug 2014)

Was the minimum limit for pH measurement a KH of 7? For some reason I thought it was 4.

I have observed, if you don't change the slide... it keeps working. I can still check the website and mobile client for updates. They still send e-mails telling me it is too hot on sunny days.

Of course, I can't guarantee the results are right. According to my client I'm now 259 days late replacing the existing slide, and it is still giving a pH reading in my marine tank (typical KH range 7 to 9). Actually I could check easily, just need to move over one of my pH probes from the tank next to it... Suffice to say, the pH value from the long expired slide is still going up and down in a daily cycle, and the values are within the expected range. I never had any ammonia so I can't comment how that performs, if at all.

I'm going to see what happens if I hit a year late on this slide


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## Sacha (18 Aug 2014)

It's 5 or 6. That's the minimum. I have been told it struggles at "less than 7"

The slides only need to be renewed for text alerts. I haven't changed mine in over a year.


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## GlassWalker (18 Aug 2014)

On the earlier question I had on accuracy of pH measurement, I have stuck one of my pH probes in tank near the seneye. The pH probe has been soaking a while and is currently measuring 8.05. Seneye reports 8.25. The probe was calibrated perhaps a month ago using 7 and 10 references. From memory, I think the particular probe I'm using now ran out of adjustment rage and actually was only going up to 9.85 keeping 7 fixed at 7. So it might be under reading by 0.05 or so assuming it is a linear error. Not sure if seneye ever gave out a measurement tolerance on pH. I can't find any specification in a quick search.


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## Yo-han (19 Aug 2014)

Spoke to them directly as well, they promised the low pH slide almost 2 years ago indeed. About the NO3 and Cl test. It will never measure live NO3. The website suggests this, but what they're building are teststrips, you place them in the water, and after that your Seneye probe will 'read' the color and translate it to a digital number. But this was 1,5 year ago as well.

All the time, I only use it for measuring light, works like a charm and cheaper than any other device!


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## Sacha (19 Aug 2014)

Presumably they've given up on the low pH slide? Run out of money?


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## pepedopolous (19 Aug 2014)

Man, I would buy low pH slides without hesitation. It would make doing pH profiles so much easier. Having said that, I think the Seneye is a cheap and effective PAR meter.

P


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## dw1305 (19 Aug 2014)

Hi all,


GlassWalker said:


> it is still giving a pH reading in my marine tank (typical KH range 7 to 9)


 It should carry on giving you a fairly accurate measurement in sea water.

There are two problems with pH probes as you approach pure H2O.

The first is that pH probes are "combination electrodes" that function as a galvanic cell. This means that as the conductivity of the water falls it takes much longer for the pH reading to stabilise. This is why you can get a more stable reading of pH by adding a neutral salt like NaCl to the water, this just raises the conductivity, but doesn't add any H+ ion donors or H+ ion acceptors. Sea water is about 53,000 microS, so conductivity isn't a problem.

The second problem is that pH is a ratio of the acids:bases. Because pH is a ratio it doesn't tell us anything about amounts. To use an analogy where sugar represents both acids and bases, if you have scales with 1 grain of sugar in the "acid" pan and 1 grain of sugar in the "base" pan you have pH7, if you have 1 cube of sugar in either pan you have pH7, and if you have 1 kg in either pan you have pH7. The pH is the same, but in reality they are very different situations.
Heavily buffered, high conductivity systems (Marine, Lake Tanganyika) will give you accurate alkaline pH values, but as you lose buffering and conductivity pH measurement with an electrode becomes more and more difficult, and really only titrimetric methods (where you add a known volume of a known strength of acid (or base) to your water and measure the colour change in an indicator compound) work.

A drop checker is actually a titrimetric method using the experimentally defined pH values from the dKH~CO2 equilibrium as a datum. In the drop checker you are adding an acid (carbonic acid (H2CO3) from added CO2) to a base (4dKH "water"), and observing the colour change in a narrow range pH indicator (bromothymol blue).


Yo-han said:


> It will never measure live NO3. The website suggests this, but what they're building are teststrips, you place them in the water, and after that your Seneye probe will 'read' the color and translate it to a digital number.


 Yo-han is right, ion selective electrodes aren't accurate where there are other anions present. The NO3 test papers again are actually another semi-titimetric method with the Seneye device working as a colourimeter.

These devices are fine if you like bits of kit, but they aren't ever going to tell you anything really meaningful about your water, unless something really strange has happened, which presumably you would have noticed anyway.

cheers Darrel


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## John P Coates (19 Aug 2014)

Sacha said:


> It's 5 or 6. That's the minimum. I have been told it struggles at "less than 7"
> 
> The slides only need to be renewed for text alerts. I haven't changed mine in over a year.


Hi Sacha,

I was told that a KH of 5dH is fine but to avoid going below this. There was no suggestion that it struggles at less than 7. From what I can gather, a guy there called Mark is the designer of the seneye sensor. The whole team is only a handful of people. My guess is that it depends who you talk to as to what answer you get.

I had no idea that the slides only need to be renewed for text alerts. That doesn't sound right to me. One half of the slide is in permanent contact with the aquarium water. Its properties must surely change over time?

JPC


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## GlassWalker (19 Aug 2014)

The Seneye uses a colour changing indicator for pH, so that may behave differently than a probe. I'm surprised it hasn't worn out totally by now, such as by the indicator either wearing out or simply washing away. Fortunately in a marine tank, pH isn't a critical measure, in that if you take care of KH, the pH will largely take care of itself. I have used the reverse, in that is pH is drifting lower, it means I haven't been topping up KH enough recently.

I think in part they recommend a monthly renewal of the slide to make sure it is fresh and accurate. Readings after that time are more of an unknown. As mentioned before, I had a look and so far haven't found anywhere where they state an accuracy for any of the measurements even with a new slide. At least in reading the manual I found out you can turn off the annoying flashing lights so I might return it into a display tank some day.


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## John P Coates (19 Aug 2014)

Yo-han said:


> All the time, I only use it for measuring light, works like a charm and cheaper than any other device!


Hi Yo-han,

I have the reef monitor and use it for light measurements - particularly PAR. But it frustrates me that, when attached to an aquarium panel, it can't do this because the light sensor receives less than 1% of the light entering the water from above. A design flaw if I ever saw one! I suggested a possible solution to seneye but perhaps I need to rig something up myself. Have you found a way around this?

JPC


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## Sacha (19 Aug 2014)

John P Coates said:


> Hi Sacha,
> 
> I was told that a KH of 5dH is fine but to avoid going below this. There was no suggestion that it struggles at less than 7.



Correction:

Here's the email they sent me a couple of years ago. 

Hi Sacha,


I think that we may have send this to you before, but in your KH level of 5, all pH measurement methods will struggle to read consistently. The link below explains this in some more detail. 


There is of course slide to slide variation. We see a worst case of 0.15 +/- with the standard distribution being far more closely matched.


I think that being at the lower end of the KH measurement, and towards the extremes of where the seneye measures you are seeing a combined effect. Whist we have never seen this level of differences between sensors in testing it could just be a case that you have had sensors that have read lower that the original one.


The low range pH sensors will be far more suitable for the pH that you are working in as they will be in the middle of the sensors range.


Until you have used the slide that we sent you we cannot make a judgement of the pack that you are using. 


There is not a difference in the slide that we send with the device and the packs of 3 that are bought. 


We will know more when we you fit the slide that we sent to you.


Best regards,


seneye support


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## Yo-han (19 Aug 2014)

John P Coates said:


> Hi Yo-han,
> 
> I have the reef monitor and use it for light measurements - particularly PAR. But it frustrates me that, when attached to an aquarium panel, it can't do this because the light sensor receives less than 1% of the light entering the water from above. A design flaw if I ever saw one! I suggested a possible solution to seneye but perhaps I need to rig something up myself. Have you found a way around this?
> 
> JPC


I don 't thinking this is a design flaw. Keep in mind that if the sensor was in direct light all the time, algae will build up really fast. Especially with calcious algae in reef tanks it will be a real pain in the *ss to clean the plastic sensor again without scratching it.

You can use it to measure PAR on certain spots and the fact that the light sensor measures continuously is more to see when your lights turn off due to a power outage or something.


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## Sacha (19 Aug 2014)

makes me so angry that they charge you $78 just to unlock the light meter features that are already inside the device... 

My Seneye Home is already a PAR/ LUX reader. In order for me to actually see those readings, I need to pay an extra $78. 

Any expert hackers on UKAPS?


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## John P Coates (19 Aug 2014)

Sacha said:


> The link below explains this in some more detail.


Hi Sacha,

When seneye refer to a link, is that the information you have quoted in your post or was there anything else?

It does seem odd that, two years ago, seneye were saying that a KH of 5dH might pose a problem.

JPC


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## Sacha (19 Aug 2014)

John,

This is the link to which the email refers: 

http://answers.seneye.com/en/water_chemistry/what_is_pH/effect_of_ionic_strength_on_PH_tests


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## GlassWalker (19 Aug 2014)

Do the lower models have the light sensor physically built in then?

On the directionality of it, I think that was a design feature. The idea being you only measure light from a particular direction so you don't get influence from elsewhere. Of course downside is the readings will generally be low in a normal mounting position.


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## Sacha (19 Aug 2014)

Yes. They are the same physical unit. The light upgrade is a software update that they seed to you only once your purchase is complete. No physical modification is needed.


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## John P Coates (19 Aug 2014)

Yo-han said:


> Keep in mind that if the sensor was in direct light all the time, algae will build up really fast.


If that were the case, the substrate of my freshwater tank would be covered with algae. It isn't. You have to take my word for it - but I will add a photo, if necessary. Granted, seneye refer to my unit as a reef monitor but then say that it is ideal for planted tanks.

JPC


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## GlassWalker (19 Aug 2014)

Sacha said:


> Yes. They are the same physical unit. The light upgrade is a software update that they seed to you only once your purchase is complete. No physical modification is needed.


I never knew that! I never liked crippleware. I assume the firmware in the unit identifies itself differently, so that the software knows which unit it is, and what to do with it. If anyone wants to try hacking, that would seem like a good starting point.

On the light and algae thing, that previous reply also mentioned reefs so things likely work differently there. Certainly I have coralline algae everywhere on one of my tanks, except the rocks for some reason...


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## John P Coates (19 Aug 2014)

GlassWalker said:


> On the directionality of it, I think that was a design feature. The idea being you only measure light from a particular direction so you don't get influence from elsewhere. Of course downside is the readings will generally be low in a normal mounting position.


Yes, the problem is that the readings are so low as to be worthless. Right now, my seneye reef monitor is showing a PAR reading of 0.2 but if I orientate it towards the light source it will be between 20 and 30. So, the sensor is seeing less than 1% of the light that is falling on that point in the tank. Consequently, it would not be possible, for example, to warn me of reducing light output from a fluorescent tube that was past its 'use by' date.

JPC


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## John P Coates (19 Aug 2014)

I ought to say that, overall, I do like using the seneye monitor despite its shortcomings. If I were to score it, I would give it 6.5 out of 10 points. My frustration is that the company is too small to respond in a reasonable timescale to the current products' shortcomings. They are currently focussing a lot of effort on their latest development, the SWS. Meanwhile, there are other higher priorities, such as those we're discussing here, that are falling by the wayside. The seneye monitor has massive potential and I hope one day to score it at least 9 out of 10.

JPC


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## dw1305 (19 Aug 2014)

Hi all,





Sacha said:


> This is the link to which the email refers: <http://answers.seneye.com/en/water_chemistry/what_is_pH/effect_of_ionic_strength_on_PH_tests>


 Fair enough, at least they are honest about why there are problems with pH measurement in water with low conductivity ("ionic strength").

Not so sure about this however, seems to contain a certain amount of scare mongering and urban myth, and doesn't exactly fill me with confidence: 





> ........In water with a low KH value, say under 2-3dKH (35.7-53.6ppm), the respiration of the plants or animals at night can cause large pH down shifts (due to CO2 production) which harm and eventually kill aquatic animals. This is called pH shock and it is due to lack of water buffering or KH. A seneye device will alert for sudden pH changes and crashes every hour of every day. Testing pH at the same time once a day will not always show if the pH has a cycle as a result of low KH........


 <http://answers.seneye.com/en/water_chemistry/what_is_KH%2C_%C2%B0KH%2C_dKH%2C_Carbonate_Hardness%3F>

cheers Darrel


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## X3NiTH (19 Aug 2014)

Wow, was there any space left for water after all the plants and fish they had to put into the tank they tested to come up with that statement!


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## John P Coates (20 Aug 2014)

dw1305 said:


> Hi all, Fair enough, at least they are honest about why there are problems with pH measurement in water with low conductivity ("ionic strength").


Hi Darrel,

Something here doesn't tally.

Although the water in my tank has a KH = 5°dH, it does not have low conductivity/ionic strength. I start with RO but, after adding salts, the resultant water has a conductivity of around 400 microSiemens and GH = 8°dH. We need to explore this further.

JPC


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## dw1305 (21 Aug 2014)

Hi all, 





John P Coates said:


> Although the water in my tank has a KH = 5°dH, it does not have low conductivity/ionic strength. I start with RO but, after adding salts, the resultant water has a conductivity of around 400 microSiemens and GH = 8°dH.


 OK that covers the "low ionic strength" issue fairly fully, and we can discount that. I've had a look at the pages on the pH pages Seneye site <what is pH -  Seneye> and it is quite good as a description (he also uses the "balance" analogy as well), but the bizarre thing is that having told you that pH is a moveable feast where you have very little buffering, he then goes onto tell you that _"pH swings, pH crashes and fish death" _will occur in soft water because tiny changes in water chemistry will have huge effects on pH! I'm not quite sure what to say at that stage, other than "_failed to join the dots together_".

There are some more bits here <what is KH.....>, which suggest adding baking soda (sodium bicarbonate (NaHCO3))  to raise your dKH, all of which suggests to be that the author comes from a Marine, or Rift Lake Cichlid, keeping background, and has extrapolated from those situations to cover the very different water chemistry in planted tanks etc.

The <Strange pH readings -  Seneye> page is also quite informative, 





> .........._The pH measurement taken by the seneye device is done using colour. The seneye+ slide changes colour dependent on the pH of the water. Using treatments that are coloured will affect the colour of the slide, this will mean that the pH output will be affected......._


 So that accounts for the slide bit, basically we are talking about the Seneye unit using colorimetry to read the colour change of a universal pH indicator fixed to a slide.

This will work quite well in heavily buffered systems (Marine, Lake Tanganyika) where large changes in water chemistry are needed to alter an intrinsically stable alkaline pH reading, but doesn't have the scale or resolution to deal with softer water, or the rapid pH changes caused by altering the CO2 ~ HCO3 equilibrium when you add pressurised CO2.

Probably the easiest way to think of the Seneye data is as a "Universal pH paper" reading presented using computer graphics.

cheers Darrel


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## dw1305 (21 Aug 2014)

Hi all,





zanguli-ya-zamba said:


> As I live in congo and tap water is less than KH 1. I use Mg and Ca to raise it at Kh 5. Does this mean that my Ph reading are not the real values ?


 Reviewing this thread, I see that I never answered this one. The pH readings in the very soft tap water are likely to be very variable, as any small changes in water chemistry will cause large changes in pH, but once the water is buffered to dKH5 you should get a more stable reading.

cheers Darrel


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## John P Coates (21 Aug 2014)

dw1305 said:


> Hi all,  OK that covers the "low ionic strength" issue fairly fully, and we can discount that. I've had a look at the pages on the pH pages Seneye site <what is pH -  Seneye> and it is quite good as a description (he also uses the "balance" analogy as well), but the bizarre thing is that having told you that pH is a moveable feast where you have very little buffering, he then goes onto tell you that _"pH swings, pH crashes and fish death" _will occur in soft water because tiny changes in water chemistry will have huge effects on pH! I'm not quite sure what to say at that stage, other than "_failed to join the dots together_".
> 
> There are some more bits here <what is KH.....>, which suggest adding baking soda (sodium bicarbonate (NaHCO3))  to raise your dKH, all of which suggests to be that the author comes from a Marine, or Rift Lake Cichlid, keeping background, and has extrapolated from those situations to cover the very different water chemistry in planted tanks etc.
> 
> ...


Hi Darrel,

Thanks for the comprehensive reply.

So, ionic strength, per se, has no bearing on the accuracy of the seneye pH reading. As you point out, the device is using colorimetry to determine pH. If the seneye monitor cannot respond to rapid pH changes, it cannot be reliably used for pH profiling. And, if there is anything slightly discolouring the water, that will also contribute to inaccuracies. Fortunately, I use RO water as my starting point so bleaching with chlorine/chloramine shouldn't be a problem. Wahey!

JPC


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## Sacha (21 Aug 2014)

So I wonder if tannins caused by wood/ cones/ leaves would render the device useless?


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## John P Coates (21 Aug 2014)

Sacha said:


> So I wonder if tannins caused by wood/ cones/ leaves would render the device useless?


They would certainly have a bearing on the pH reading.

JPC


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## GlassWalker (21 Aug 2014)

Before I moved the Seneye to my marine tank, it was in a hard water tank (mollies, britlenose). I did have lots of bogwood, and added alder cones, IAL, teak tree leaves too as the plecos seem to like them. I don't recall getting unexpected pH readings, but couldn't say they were verified as accurate either.


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## dw1305 (21 Aug 2014)

Hi all,





GlassWalker said:


> I don't recall getting unexpected pH readings, but couldn't say they were verified as accurate either.


 It would probably depend a little bit on how tannin stained the water is, and also the colour of the slide. Without knowing how the slides in the Seneye are read, what would normally happen is that a specific wave length of light (in nanometres and corresponding to the colour you are interested in) would be shone through the slide, and the amount of absorbed light recorded.  Presumably the Seneye unit scans at a number of different wave lengths from ~700 nm (red, acid) through green ~550 nm, (neutral, pH7) to ~450nm (blue, alkaline).

The wavelengths of light (in nm) are shown below with the spectral reflectance curves of the two blue colours shown (unsurprisingly absorbed mainly in the blue wavelengths of light around 475nm), you can also see a small red peak, meaning that the colours would look slightly purplish to a camera film, but not to the human eye which is very sensitive to blue wavelengths of light.




In the case of Seneye for the blue alkaline pH readings the tannins would have little effect, unless the light path was very long (and I'm pretty sure it isn't), or the water very heavily tannin stained.

The same is not true for the more acid pH colours (yellows, red and oranges) where there would be interference from the similarly coloured tannins, which would absorb at these same wave lengths.

cheers Darrel


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## dw1305 (21 Aug 2014)

Hi all, 





dw1305 said:


> unsurprisingly absorbed mainly in the blue wavelengths of light around 475nm


 I'm just going to correct the post above, mainly because I start writing it before I'd found a suitable image and I couldn't find exactly what I wanted, so I put in a reflectance curve, rather than an absorbance one without changing all the text. What it should say is 





> unsurprisingly reflected light is mainly in the blue wavelengths of light around 475nm


 If we stick strictly to absorbance, rather than reflectance, the whole process would be inverted, so that the peaks on the graph become troughs and vice versa. This is why leaves are green, they are reflecting green light and absorbing light at the red and blue end of the spectrum.  

cheers Darrel


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## X3NiTH (21 Aug 2014)

Is it known if the unit performs a white balance reading to gauge the colour of the water before it calculates the results?


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## GlassWalker (21 Aug 2014)

Looking at the slide, there is an area of white around one of the pads so there is a possibility to do a white balance or zeroing.


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