Thread: Hanna Chlorine Tester!

Originally Posted by Maddog1

Hi/ Can anyone please explain to me which Hanna Chlorine tester I need. Total Chlorine/Free Chlorine? Thank you

now some of this this may be a bit controversial

you need the TOTAL chlorine checker for your pond/tap water.
Either the HC-761 parts per billion (ppb)
or HC-711 parts per million (ppm)

a FREE chlorine checker along with a total chlorine checker will tell you the level of free chlorine and by deduction the level of chloramine (if you have it.)
so for the purposes of what carbon to buy it can be helpful, but not necessary to have a free chlorine checker.

the longterm chlorine saftey threshold for koi is 0.02ppm (20ppb)
so you need something that can measure to 0.02ppm (20ppb)

a HI-711 ppm total chlorine checker has an accuracy of +/- 3% (0.03ppm) (30ppb) (roughly)
so it's possible it may give you a zero reading when levels could be higher than 0.03ppm
but in practise i think they are not as far out as that at the very low levels as the range is 0.00ppm to 3.5ppm
so with a PPM checker i'd change carbon or add dechlorinator at it's lowest positive reading (0.01ppm)

I've got the HI-761 total chlorine ultra low range which measures in PPB
it has a +/- 5% accuracy (5ppb) (roughly)
so though it too can potentailly give a zero reading at (0.005ppm)(5ppb)
in practise i don't think it is so far out as my repeat tests are within a close range.
so i note if the chlorine starts to rise at 5-10ppb but don't bother to replace carbon ect until at 20ppb or above as these levels would only just about register 0.01ppm on a HI-711ppm checker.

But...all these test accuracies for both checkers are at a water temperature of 25C.
so if you test winter water a 4C the results may be wildly different.

I also use Syd's DPD4 palin test tablets method (top down veiw of 10ml sample tube) for quick checks or to back up my hanna checker if i'm unsure of the reading for any reason
https://www.mankysanke.co.uk/html/ef...orination.html

Originally Posted by Maddog1

Do you use the rapid DPD4 tablets Dave. I'm having trouble with them , not fully dissolving.

I feel your pain....Some of the dpd4 tablets are a right pain to dissolve. I've broken the bottom of many a tube trying to mash them up

Originally Posted by Maddog1

Hi/ Can anyone please explain to me which Hanna Chlorine tester I need. Total Chlorine/Free Chlorine? Thank you[IMG]file:///C:/Users/Syd/AppData/Local/Temp/msohtmlclip1/01/clip_image001.gif[/IMG]

As Dave said earlier, DPD4 test tablets are Total Chlorine tablets so they test for the total value of Free Chlorine plus any Chloramine and any trace amounts of other compounds that contain chlorine that are sometimes in tap water so they are the correct ones for koi keepers to use to check that dechlorination is complete.

There are other DPD test tablets that will determine either Free Chlorine and/or Chloramine and I regularly used these when designing or installing water parameter control equipment to determine the ratios between Free Chlorine, Chloramine and Total Chlorine for a complete analysis of water as part of a chemistry procedure called "Sodding About".

Some people who know how to use DPD tablets to do these procedures sometimes post the various methods on FaceBook but I think that this is showing off by describing procedures that don't have any real value for koi keepers over just using a DPD4 to verify that dechlorination is or isn't complete.

Originally Posted by Ruffers22

I feel your pain....Some of the dpd4 tablets are a right pain to dissolve. I've broken the bottom of many a tube trying to mash them up [IMG]file:///C:/Users/Syd/AppData/Local/Temp/msohtmlclip1/01/clip_image002.gif[/IMG]

DPD4 tablets come in two versions which will be (or should be) clearly specified in the sales blurb.

There are rapid dissolving DPD4s which have a filler that blows them apart when they are in contact with water so they dissolve rapidly. However, the filler leaves the sample with a white tint. They still show the pink due to chlorine or chloramine which is easily seen when used in a manual kit but are no good for use in a photometer which needs a clear sample to send a light beam through.

There are photometer grade DPD4s for use in a photometer, (obviously), which show the pink due to chlorine or chloramine but leave the sample otherwise clear. They can also be used in a manual test. Unfortunately with no dissolving filler, they are difficult to dissolve and require crushing in order to help them dissolve. When crushing photometer grade tablets, don't hold the cuvette/sample tube but place it on a firm surface then the bottom won't be at risk of breaking. (I soon got used to doing that early on in my career playing with water for a living after breaking a few glass photometer cuvettes at twenty quid a pop back in the early 80's.)