Chlorine detected from 3 stage filter but not in the pond

[LOCOSPOTTER]

I have 3 stage filter system which has had new cartridges fitted done a check for chlorine on filter outlet which proved positive but pond water is clear. Using DPD4 tablets and repeated test 4 times and same result each time. What's going on I am confused.

[Maddog1]

I have 3 stage filter system which has had new cartridges fitted done a check for chlorine on filter outlet which proved positive but pond water is clear. Using DPD4 tablets and repeated test 4 times and same result each time. What's going on I am confused.
Hi/ Is the flow too fast?

[davethefish1]

dependant on your mains tapwater chlorine/ chloramine levels,
a 3 pod may not be enough to remove all the chlorine.
in fact, unless your chlorine is very low probably isn't. :)

[Manky Sanke]

I agree and, if a low level of chlorine/chloramine is present in the output of a trickle feed, it will be diluted to a level that's too low to detect by the volume of water in the pond.

This isn't an excuse to encourage laxity in dechlorination, we should still try to get a zero chlorine output from a purifier, but is an explanation of why the level of chlorine/chloramine is high enough to measure out of a purifier but not high enough to measure after it's been diluted.

[LOCOSPOTTER]

Thanks to all members who replied I have had an email from filter supplier he advice that using DPD4 tablets is not chlorine in the water from outlet but is the oxygen generated in the cartridge which the DPD4 tabs are detecting. I can't disprove this so I will leave it up to members more knowledgeable than me before I comment any further. I done a 3250 litre water change on a 20000 litre pond and no chlorine detected.

[Maddog1]

I'm far from being an expert, but I wouldn't have thought that to be the case :confused:

[Maddog1]

Hi/ I've got a 36" big blue, but I still use Sodium Thiosulphate. Just ordered 5kg of ebay £26

[Manky Sanke]

Thanks to all members who replied I have had an email from filter supplier he advice that using DPD4 tablets is not chlorine in the water from outlet but is the oxygen generated in the cartridge which the DPD4 tabs are detecting. I can't disprove this so I will leave it up to members more knowledgeable than me before I comment any further. I done a 3250 litre water change on a 20000 litre pond and no chlorine detected.

"It ain't my fault Guv" :) :confused: How many times do we hear that blank denial?

Take a jug of water from the purifier and do a DPD4 test.

If it shows a positive result, add a drop of dechlorinator to the jug and test again. If you get a clear result, ask him to explain why it goes clear when dechlorinator is added.

If you still get a positive result, it's oxygen that is being generated by some strange chemistry in the purifier so ask him to explain how carbon does that in his purifier and not in the thousands of other purifiers where the output is measured with DPD4 tablets.

[davethefish1]

Thanks to all members who replied I have had an email from filter supplier he advice that using DPD4 tablets is not chlorine in the water from outlet but is the oxygen generated in the cartridge which the DPD4 tabs are detecting. I can't disprove this so I will leave it up to members more knowledgeable than me before I comment any further. I done a 3250 litre water change on a 20000 litre pond and no chlorine detected.

hmmm.... smells like,,,,:D

https://i.postimg.cc/QtSmB7jc/pile3.jpg


(https://postimages.org/)to be fair though no way a 10" 3 pod is going to be enough for a 20,000 litre pond.
you need a big blue to have the speed of flow needed when large water changes are neccesary. :)

[Mannh85]

@LOCOSPOTTER (https://www.koiforum.uk/members/38000.html) When using the DPD4 tablets you need to go off the initial reading in 10ml of test water, over time the tablet will get pinker pinker so if you're leaving the DPD4 to stand over time this might be why you keep getting a reading. This is the info I go by anyway which I believe was from manky's website.

[Frimley Koi keeper]

When I use DPD4 tablets in 10ml of water if there was traces of tap water conditioner (which contains ST) in the water the water sample took hours to show even a slight change to pale pink if at all. Straight from the tap same method - pink instantly. From the pond same method - clear then after a few minutes it went pink like it should.

In the past I have used 10" standard 3 pod systems and they can only run at a very low flow rate, maybe 1.5 lpm max for 6 months to a year and have also used a 10" big blue jumbo 3 pod system which claimed 8 lpm flow rate. I was running that at 5 lpm and that was working OK for at least a year then it started to let chlorine through so tried dropping to 3 lpm and even 1 lpm but it still let chlorine through. I started adding Interpet tap water conditioner and then upped the 3 pod to 12 lpm as it was then just used to stop heavy metals and the ST in the Interpet was dealing with the chlorine. Worked a treat and made tops ups much quicker. If you are using it for a trickle in and out then as Dave rightly said, you'll need something a bit bigger than a standard 3 pod 10" system.

[Frimley Koi keeper]

There's 2 versions of the DPD4 tablets. Rapid dissolving and slow dissolving. I always use a test tube style tablet crusher to break the DPD4 tablets up even if they are fast dissolving. It looks like a tiny paddle from a boat. Can also use a cocktail stirrer. Manky Sanke even suggested an old ladies knitting needle :)

[Manky Sanke]

Yep, this is a picture of proper tablet crushers from the article on my site but anything that looks like the blunt end of one of your Granny's old knitting needles will do.

http://www.mankysanke.co.uk/assets/images/autogen/a_Plastic_stirrer__200_.jpg


Questions Answered (http://www.mankysanke.co.uk/html/questions_answered.html)

[Frimley Koi keeper]

Yes that's exactly what I was trying to describe.

Save attacking an old granny ;)

[Frimley Koi keeper]

I see the one on the left is the deluxe version as it comes with a test tube and tablet ;)

[Manky Sanke]

@LOCOSPOTTER (https://www.koiforum.uk/members/38000.html) When using the DPD4 tablets you need to go off the initial reading in 10ml of test water, over time the tablet will get pinker pinker so if you're leaving the DPD4 to stand over time this might be why you keep getting a reading. This is the info I go by anyway which I believe was from manky's website.

Yep, that's correct. Look for any colour change as soon as the tablet has dissolved because dissolved oxygen will cause it to begin very slowly turning pink if you leave it more than a few minutes.

[Frimley Koi keeper]

With tap water I've seen it literally start to go pink as the tablet hits the water. Yep! Definitely chlorine there :D