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03-12-2019, 10:49 PM #1
Chlorine or chloramine levels DPD No 4 info
Hi all was looking for info on DPD no 4 and found the below information very informative and helpful so thought I would share.
Hopefully help someone
DPD No 4 Tablets:
For those keeping fish and looking for DPD No 4 tablets to test for the presence of Chlorine or chloramine levels then the following information may assist.
In the UK domestic water supplies are normally in the region of 0.5 mg/L but can be raised to about 4 mg/L.
The maximum tolerable level for chlorine or chloramine for Koi is 0.02 mg/L. This is one tenth of the value at which rapid deterioration of the respiratory system begins so, even at normal tap water chlorine values of 0.5 mg/L, exposure to undechlorinated water can often lead to fatalities.
Proprietary dechlorinators have recommended dose rates that will typically fully dechlorinate water with chlorine/chloramine levels up to 2.0 mg/L and so will provide full dechlorination at normal supply values. However, this dose rate can only provide partial dechlorination if there is an increased level due to the higher values sometimes added by water supply authorities.
Since the maximum value of chlorine that Koi may be exposed to without harm is 0.02 mg/L measuring such low values is difficult.
Properly dechlorinated water will contain no chlorine; incompletely dechlorinated water (obviously) will contain some chlorine. Therefore, in order to ensure water has been fully dechlorinated it isn’t important to know the exact value of any remaining chlorine in the water, all that is necessary is to know that there is either “no chlorine” or “some chlorine”. The DPD 4 chlorine test is suitable to use as confirmation that water has been fully dechlorinated.
DPD 4 tablets are fast and simple. All it takes to do the test is some DPD 4 test tablets, a sample tube and a piece of white paper. The method is described below.
How to Test
Clear results confirm that the water is totally free of any form of chlorine; any trace of pink indicates that the water hasn’t been fully dechlorinated and is therefore not safe to use until additional dechlorinator has been added and a second test indicates “clear”
Fill a standard 10 ml sample tube with the water to be tested and drop in a DPD 4 tablet. Don't look through the side in the usual fashion, place it on a white surface and look down through it. This will make it easier to see a faint colour change. If there is no chlorine or chloramine in the sample it will stay clear. The tablets begin to show a noticeable pink colour change at around 0.01 mg/L so, although this is too indistinct to be able to say what the actual level is, it is valid to say "no colour means no chlorine". If you can see the faintest pink colour in the sample, it means there is a trace of chlorine in it and there shouldn't be.
Strictly, a DPD 4 tablet doesn’t just test for chlorine, it is also looking for any other oxidising reaction, so, although it provides an instant colour change when any form of chlorine is present, it will then very slowly produce a pink colour change due to dissolved oxygen. This is especially noticeable if the sample is left exposed to the air so that more and more oxygen can enter the solution. Look for the colour change immediately because even if there is no immediate pink colour, showing that there is no chlorine in the sample, after several minutes dissolved oxygen will begin to turn it pink anyway.
Types of DPD 4 tablets
There are two types of DPD 4 tablets. The "Rapid Dissolving" tablets do exactly that but the ingredient in the tablets that causes them to rapidly disintegrate and dissolve results in them tinting the water white. They still turn the sample anywhere from pale pink if there is a trace of chlorine or chloramine present to deep pink if there is a lot of it present.
There are also "Photometer Grade" DPD 4 tablets which are a little more expensive. These are difficult to dissolve but they leave the sample totally clear unless there is any form of chlorine present. Don't shake the sample tube vigorously in an attempt to dissolve these types of tablets; that will dissolve oxygen into the sample and may cause a false positive reading. The tablets should be crushed in the bottom of the sample tube with a specially made tablet crusher or with something that resembles the blunt end of a plastic knitting needle. After that, a couple of inversions of the tube will be all that is necessary to ensure good mixing.
Both tablets react identically to chlorine/chloramine the only difference is that the rapid dissolving types add the white tint in addition to any pink colour change due to chlorine, whereas the photometer grade tablets leave the sample clear except for any pink colour due to the presence of chlorine.
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freddyboy Thanked / Liked this Post
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04-12-2019, 07:24 AM #2
Nice one mate . I crush mine dpd4 tablets in the test tube. Have you tested yet.
I have a 3 pod dechlorinator filter on my setup. But do not trust it. So I use sodium
Thiosulphate . ST Crystal's. And I add 2 teaspoons of ST. Every 3 days. A lot of us on here do this. As we trickle into the pond.
And do not trust the pod filters.
I use this site for water chemistry.
Home
I had a couple of fish with ulcers. I believe it was because of chlorine getting into my pond.
Never had a problem since using st Crystal's. For water changes. And trickle in and out. Cheap as chips of ebay.
Fred
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john1 Thanked / Liked this Post
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04-12-2019, 08:27 AM #3
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freddyboy, Manky Sanke Thanked / Liked this Post
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04-12-2019, 09:11 AM #4
Chlorine or chloramine levels DPD No 4 info
@freddyboy that’s interesting that you guys do not trust your filters.
I naively thought buying a purpose designed filter (that was not cheap ) would mean I did not have to worry about Chloramine and chlorine anymore.
I did read in the manual that the unit is designed to “reduce” incoming chlorine of 0.5ppm at a flow rate of 4 litres a minute. I am not set up on a trickle but fill at 2 litre flow rate.
I have not tested the water yet but I have 100 tables on their way to me.
Have you found any results in your pond to give you reason to not trust the filter?
I will look into your other suggestions.
Always learning
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freddyboy Thanked / Liked this Post
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04-12-2019, 09:58 AM #5
Yes Mike I did find chlorine in the pond water. And that was a cause of ulcers. It burns them I believe. The fish. Since though using ST. I have not had a problem.
John 1 and lee helped me on the subject of killing it off. Ie how much to add to the water on my gallonage of the pond.
I still use the 3 pod stage filter though for taking metal s out the water.
I tested the other day on my grow on qt.
And there was a slight pink tint. So water changes are done with st. I am not saying all are letting it through. But in my case it does. So I now don t trust them. And put st
In the water to make sure.
Fred
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04-12-2019, 10:44 AM #6
Yes John, that's just a rewrite of the DPD4 test that I came up with in 2014 and put on my website, much of which is a word for word copy without bothering to credit where it's been copied from.
I'm pleased to share what playing with water for a living for thirty odd years has taught me and that is why I built the site and pay a small fortune to maintain it for no benefit to myself. However, if Mike had just posted a link to the original article then anyone reading it would have seen the explanatory diagrams and pictures that make it clearer and easier to understand.
Read the original article complete with explanatory pictures and a diagram showing how to do it properly here:
Questions Answered
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04-12-2019, 11:08 AM #7
@Manky Sanke I was not trying to discredit anyone. The thread was not copied from your site if there was additional media content I would have shared the link.
If you are interested where I found it it was here https://www.testallwater.co.uk/catal...d-no-4/id/784/
Btw. Its a great read so thank you!
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04-12-2019, 11:26 AM #8
Thanks Mike I'll ask them to remove it because they've deliberately copied my article and that's blatant plagiarism.
However, if you copy stuff from any site, it's only a matter of politeness to credit the site where you copied it from. Better still, just post a link which is quicker and gives readers any pictures or diagrams that make an article clearer and also allows them to go on and read any related information on the site.
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04-12-2019, 12:33 PM #9
Personally I am not a fan of just adding links as it happens so regularly where I am browsing a forum and find the links are broken (page no longer exists) I find this frustrating. I am happy to add a link as a reference of content/source
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04-12-2019, 01:02 PM #10
I know the frustration of broken links when websites remove stuff or move it around. However you can post links to anything on my site because everything is intended to be a permanent source of information for the koi hobbyist with nothing ever being removed or shifted around.
All I ever do is add more stuff or update what is already on there whenever there is something I think I can add in response to feedback on koi forums or FaceBook which is another reason why it's better to follow a link to the article itself and see the most up-to-date information.
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anne Thanked / Liked this Post
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05-12-2019, 12:25 AM #11
I still have a brand new Vyair 20" 3 pod that i haven't been able to get to run yet without letting chlorine through on standard cartridges...
so i went back to using RO membranes.
but you basically need to buy much more expensive carbon cartridges for the pods.
here is a thread by RS that covers some of the issues of dpd tablets and dechlorinators pretty well...
https://www.koiforum.uk/water-treatm...nfo-ideas.html
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05-12-2019, 01:47 PM #12
Are you sure your filter is definitely removing Chloramine?
Chloramine cartridges can be quite expensive and sometimes the claims are not quite accurate.
Have a read of this:
https://www.koiforum.uk/water-treatm...nfo-ideas.html
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05-12-2019, 01:48 PM #13
Ha ha, just read your post dave, thanks for linking to my dechlorinator thread!
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05-12-2019, 01:52 PM #14
It’s a good thread!
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05-12-2019, 02:44 PM #15
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RS2OOO Thanked / Liked this Post
Running heater at low temp?
Covering the pond with polycarb should be enough to stop water temps dipping below 6C for the most...