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23-01-2021, 04:40 PM #1
Chlorine readings after carbon filters and in pond
I got a Hannah Chlorine tester for Christmas ULR, and got a low reading after my little big blue (11ltr), so I changed the Carbon and was still getting a low reading?
I then decided to get another little big blue and run them in line to give 22ltrs worth of carbon. And you have guessed it i am still getting a low reading!!
Flow rate is only 100ml a minute and have been advised these little big blues could handle upto 1.5 ltrs per minute with new carbon.
Reading of 025ppb
Water reading from tap flashes 500 (saying to high of a reading)
And Pond water also shows a low reading of 034 ppb (this is now worrying me)
When using the DPD4 tablets there is no pink showing at all?
I am now thinking could the New Hannah checker be faulty or has anyone else had a similar problem?
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23-01-2021, 06:48 PM #2
With all the extra chlorine being added to the mains water supply due to the COVID situation a few people are finding their carbon filters aren't stopping chlorine getting through like they used to. You could try ST or a tap water conditioner and see how that works for you.
My dechlorinator is supposed to be able to run at 8 lpm but I only run it at 5 lpm then noticed the fish were acting oddly, checked the water and found chlorine was getting through. I slowed the flow rate down to 3 lpm but still no joy and then found no matter how slow I ran it chlorine was getting through. The filters weren't that old either so maybe once it starts to get through it's time to replace the filters?
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john1, RevinKevin Thanked / Liked this Post
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23-01-2021, 08:45 PM #3
Dont know anything about meter readings but I now have to add a double dose of s/t as looks like the water board have upped the chlorine as Frim said.
John
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24-01-2021, 01:16 AM #4
I would add some ST to a pond water sample and test that. If you still get a reading then something is up with the meter.
DPD4 tablets show pink at any trace of chlorine so again with no pink that points to the meter, but do the ST crystal test to be sure.
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24-01-2021, 08:45 AM #5
Chlorine readings after carbon filters and in pond
Hi when I read this I was wondering if your hanna unit could be measuring chloramines, I’m pretty sure that carbon filters cannot remove this.
Is it the total chlorine hanna unit you have?
If so I find this info from hanna.
Code:The HI761 Checker measures Total Chlorine. The Total Chlorine Checker and Free Chlorine Checker can be used together, subtracting the difference from Total minus Free chlorine and this would give you a basic chloramine total number. The theory behind this method of testing is that the total chlorine test value is the sum of the free chlorine, monochloramine and dichloramine present in the water while the free chlorine test value gives the free chlorine concentration only. The difference between the two values is referred to as combined chlorine and is theoretically the sum of the monochloramine and dichloramine concentrations present.
I have seen suggestions that 0.02ppm is a level that is ok but higher can have an ill effect on the haemoglobin in the red blood cells thus effecting the fishes ability to carry oxygen, chlorine has the same effects on a fish as nitrite.
Sent from my iPhone using TapatalkLast edited by Mikeh83; 24-01-2021 at 01:10 PM.
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24-01-2021, 12:55 PM #6
The standard carbon filters only remove chlorine but you can buy the heavy duty versions that remove both chlorine and chloramines I believe?
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RevinKevin Thanked / Liked this Post
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24-01-2021, 12:58 PM #7
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24-01-2021, 01:22 PM #8
I will try the ST option and re-test, does the ST nutralise Chloramine?
This is an image of the DPD4 test, didn't question it to be honest until I got the Hannah meter!!
Screenshot_20210124-121510_Gallery.jpgLast edited by RevinKevin; 24-01-2021 at 01:30 PM. Reason: Unable to attach image, without using desktop version on phone
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24-01-2021, 01:35 PM #9
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24-01-2021, 01:44 PM #10
Don't like to shake it and add oxygen, I was on the understanding that you add the tablet and if any trace it will immediately turn pink?
That image was taken after a couple of minutes after the tablet was added.
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Frimley Koi keeper Thanked / Liked this Post
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24-01-2021, 01:50 PM #11
Normally you still need to crush the tablet even if you get the rapid dissolving ones and then take a look down through the top of the test tube onto a white surface to get a good reading of colour change.
It does change colour normally after a couple of minutes as it oxidises so you need to read it as soon as it's fully dissolved.
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24-01-2021, 01:50 PM #12
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24-01-2021, 01:55 PM #13
Have a look at Manky Sanke's website here -
Questions Answered
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25-01-2021, 09:45 AM #14
Just had a call from Seven Trent this morning confirming there is no Chloramine added to my water supply in my area.
They did say they would add it in more rural areas as Chlorine breaks down quicker.
So just waiting for the ST to arrive and will test again.
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Mikeh83 Thanked / Liked this Post
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25-01-2021, 10:10 AM #15
Apparently you can check for chloramine yourself.
I think I'm remembering what Manky Sanke told me correctly. Take a sample water and let it stand for a day or so (that's the bit that you need Syd to confirm how long you need to leave it standing) then you check it with your DPD4 tablets. As chlorine gasses off but chloramine doesn't if you get a reading you have got chloramine in your water.
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25-01-2021, 10:11 AM #16
That’s good to have that confirmed.
I had read previously if you test your source water for ammonia and it’s present there’s a good chance Chloramine has been added.
Interesting they said about adding it in more rural areas as I thought it was more used in central London
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25-01-2021, 10:14 AM #17
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Manky Sanke Thanked / Liked this Post
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25-01-2021, 12:24 PM #18
That's correct.
The half life of a compound is the length of time it takes to decay or decompose to half its original strength (under any given set of circumstances).
The half life of chlorine due to natural gassing off in well aerated water exposed to the atmosphere can be as short as about 2 hours (very dependent on aeration and sunlight).
With a 2 hour half life, whatever level of chlorine is in the water will reduce by 50% every 2 hours. E.g. 50% after 2 hours; 25% after 2 more hours; it will be 12.5% after 6 hours and it will be 0.0625% of its original level after a total of 8 hours. If water containing only chlorine is aerated overnight, the residual level will be insignificant.
Chloramine has a half life of anywhere from a week to 23 days especially at higher values of pH so, if there is chloramine in the water, aerating it overnight will remove to chlorine but the chloramine will still be there.
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25-01-2021, 12:26 PM #19
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Manky Sanke, Ajm Thanked / Liked this Post
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26-01-2021, 12:46 AM #20
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Frimley Koi keeper Thanked / Liked this Post
The Daily pond temp thread
Yep , forecast snow here ! Hoping so more money to be made gritting lol Sent from my SM-S918B...