Welcome to Koi Forum. Is this your first visit? Register
Page 1 of 2 12 LastLast
Results 1 to 20 of 21
  1. #1

    Crushed oyster shell

    Morning guys .

    ive just added some crushed oyster shell to my filters (Iíve added 2.5kg in mesh bags) as Iíve read it can help maintain ph and kh which Iím having a bit of trouble with this year for unknown reasons .
    can somebody tell me how do you know when the shell is spent and no longer doing what I hope it will do.
    also would 2.5kg be enough for a 3300gallon pond or should I just whack the full 5 kg in to filter? Currently have it in my moving bed suspended in the middle .

    thanks Iím advance for any help with this .



  2. #2
    Senior Member Rank = Yonsai rolo's Avatar
    Join Date
    Nov 2020
    Location
    wakefield
    Posts
    178
    Thanks / Likes
    271
    never noticed a difference when i had it in my old filters i binned it and everthing carried on as normal.

    keith

  3. Thanks ohfortunate1 Thanked / Liked this Post
  4. #3
    Senior Member Rank = Mature Champion davethefish1's Avatar
    Join Date
    Apr 2019
    Location
    Bedworth
    Posts
    2,281
    Thanks / Likes
    5370
    the shell will be 'spent' when it's gone.... dissolved....
    but that is unlikely unless your water is extremely soft.
    ideally it needs acidic conditions to dissolve and raise KH,
    more acidic that your pond ever wants to get...

    i've tried using calcium carbonate material on in my old pond when i was running RO, KH was around 2, and ph was low 7's
    but it wouldn't 'dissolve' quickly enough to keep KH up so ended up dosing sodium bicarbonate.
    i did toy with the idea of using a calcium reactor like i had on my reef tank, but the demands of a pond are much higher due to water changes ect...
    made it untenable.

    what is your tapwater KH, as most people just need to do increase water changes to keep KH up?

  5. Thanks Ajm, ohfortunate1, Manky Sanke Thanked / Liked this Post
  6. #4
    Senior Member Rank = Supreme Champion Ajm's Avatar
    Join Date
    Mar 2018
    Location
    Durham
    Posts
    8,125
    Thanks / Likes
    16155
    As DTF mentioned water changes and bicarb are the preferred way to go on this I have pretty much 0 kh from the tap and find that my pond is pretty stable with my maintenance routine once you find what your pond needs over a few weeks of testing and testing it'll just become second nature ie to do your weekly 10 percent and add half a cup of bicarb in (when you add your St if used ) . . I have very soft water which can be a blessing as some people pay a fortune for RO and the only problem I've had is when I took my eye off the ball and didn't do my routine over the winter months

    Please have a read over these 2 links (and the whole site really brilliant)

    As it talks about bicarb kh ph and oyster shells
    Alkalinity

    Understanding Buffering

    Sent from my SM-G973F using Tapatalk
    Freddyboy the legend

    "we are water keepers first"

    Johnathan

  7. Thanks Manky Sanke Thanked / Liked this Post
  8. #5
    I’ve had my pond for over 25 year this is the 1st time I have had an issue with PH KH so unless my water company has made changes to the water nothing else has changed .

  9. #6
    Senior Member Rank = Supreme Champion Ajm's Avatar
    Join Date
    Mar 2018
    Location
    Durham
    Posts
    8,125
    Thanks / Likes
    16155
    Have you checked tap water

    Sent from my SM-G973F using Tapatalk
    Freddyboy the legend

    "we are water keepers first"

    Johnathan

  10. Thanks ohfortunate1 Thanked / Liked this Post
  11. #7
    Good idea ��

  12. #8
    So I carried out the tests from the Tap and my KH is 1 drop �� used to be about 4 and to add to this my ph is acidic to the point it looked like I had urinated into the tube.
    maybe need to speak with water board and see if they’ve changed anything.

    Thanks for all the advice guys .

  13. #9
    The subject of ďis calcium carbonate any good as a buffer?Ē is a difficult concept to understand so I'll explain it as slowly as possible in easy steps.

    There are many forms of calcium carbonate that you can put into a pond such as limestone chips or powder, oyster shells, eggshells, calcified algae etc.

    Calcium carbonate is poorly soluble in water with a pH in the normal range for koi keeping unless carbon dioxide is also present. If carbon dioxide is present then the calcium carbonate reacts with it to make calcium and bicarbonate both of which are soluble in water.

    If you put any form of calcium carbonate into a well aerated koi pond there won't be a significant level of carbon dioxide because, apart from adding oxygen, aeration also gasses off the carbon dioxide from fish respiration. Without carbon dioxide being present the calcium carbonate won't dissolve to any great extent which means that very little bicarbonate will be produced so it will do very little to stabilise the pH.

    If you put any form of calcium carbonate into a pond that isn't well aerated it will dissolve according to how much carbon dioxide is dissolved so some bicarbonate will be produced and that will have some effect on the stability of the pH.

    It all depends on how poorly aerated the pond is. If it isn't too bad and there's only a small amount of carbon dioxide present there will be a small buffering effect. If the aeration is very poor and there's a lot of carbon dioxide present there will be a lot of bicarbonate produced so there will be a larger buffering effect.

    It isnít true to say that limestone or shells won't dissolve in a koi pond. What is true is that calcium carbonate is virtually insoluble in water with a pH value above 7.0 unless there also is dissolved carbon dioxide present. This is the important statement to remember.

    If carbon dioxide (CO2) is dissolved in water it forms carbonic acid (H2CO3) and it's the amount of dissolved CO2 that makes the effect of shells unpredictable. If there is a high level of dissolved CO2 then shells will dissolve freely. If there is good aeration which, not only gives high dissolved O2, but also near-zero dissolved CO2 then calcium carbonate (CaCO3) will be nearly insoluble and therefore shells and other forms of calcium carbonate will have no significant effect on pH swings.

    The actual pH if calcium carbonate is used as a buffer isn't predictable because it depends on the level of dissolved carbon dioxide that is present. However, its maximum pH value is in the region of 10 to 11 and you can only limit this by water changes because the supply water wonít have such a high pH so it will tend to reduce the rise.

    A final point is that sodium bicarbonate will buffer the pH to a maximum value of 8.4 no matter how much is added and the rise in KH is predictable because it can easily be calculated.

    I can do the chemistry if anyone wants me to show what actually happens but the bottom line is that, if anyone finds that shells dissolve in their pond then they either have allowed their pH to fall below 7.0 or they have a significant level of dissolved CO2.

  14. Thanks Ajm, dbs Thanked / Liked this Post
  15. #10
    Thanks Manky
    that makes interesting read ����

  16. Thanks Manky Sanke Thanked / Liked this Post
  17. #11
    Quote Originally Posted by ohfortunate1 View Post
    Thanks Manky
    that makes interesting read ����
    Did you understand it?

  18. Thanks Ajm Thanked / Liked this Post
  19. #12
    I think so Thankfully you put the last bit in there regarding low ph. �� which I have direct from the tap about a 4 ���� so maybe going down the lines of sodium bicarbonate would be more beneficial . This must have something to do with my local water company and a change they’ve made my parameters have never been like this .

  20. #13
    Senior Member Rank = Supreme Champion Ajm's Avatar
    Join Date
    Mar 2018
    Location
    Durham
    Posts
    8,125
    Thanks / Likes
    16155
    Quote Originally Posted by ohfortunate1 View Post
    I think so Thankfully you put the last bit in there regarding low ph. �� which I have direct from the tap about a 4 ���� so maybe going down the lines of sodium bicarbonate would be more beneficial . This must have something to do with my local water company and a change theyíve made my parameters have never been like this .
    When you checked the tap water for pH did you let it stand over night first?? As it needs time to gas off first. . Tap pH I believe shouldn't be anything below 6.5 as 4 is really acidic and would tickle your eyes abit when washing

    Sent from my SM-G973F using Tapatalk
    Last edited by Ajm; 25-09-2021 at 08:59 AM.
    Freddyboy the legend

    "we are water keepers first"

    Johnathan

  21. #14
    Nope straight from Tap

  22. #15
    Senior Member Rank = Supreme Champion Ajm's Avatar
    Join Date
    Mar 2018
    Location
    Durham
    Posts
    8,125
    Thanks / Likes
    16155
    Quote Originally Posted by ohfortunate1 View Post
    Nope straight from Tap
    Leave it a few hours or over night and if you have a small aquarium air pump to stick in for good measure but not needed

    Sent from my SM-G973F using Tapatalk
    Freddyboy the legend

    "we are water keepers first"

    Johnathan

  23. #16
    Quote Originally Posted by Ajm View Post
    Leave it a few hours or over night and if you have a small aquarium air pump to stick in for good measure but not needed

    Sent from my SM-G973F using Tapatalk

    Sorry, Jonathan but aeration is needed not optional and it's also important to add a trace of dechlorinator or sodium thiosulphate since aeration alone is slow to gas off chlorine and would take days to gas off any chloramine in the supply.

  24. Thanks Ajm Thanked / Liked this Post
  25. #17
    Senior Member Rank = Supreme Champion Ajm's Avatar
    Join Date
    Mar 2018
    Location
    Durham
    Posts
    8,125
    Thanks / Likes
    16155
    Quote Originally Posted by Manky Sanke View Post
    Sorry, Jonathan but aeration is needed not optional and it's also important to add a trace of dechlorinator or sodium thiosulphate since aeration alone is slow to gas off chlorine and would take days to gas off any chloramine in the supply.
    Do apologise Syd happy to be put right helps me for next time .

    Sent from my SM-G973F using Tapatalk
    Freddyboy the legend

    "we are water keepers first"

    Johnathan

  26. #18
    No problem Jonathan, there are many myths on the Internet, including the myth that it's easy to gas off chlorine by aeration so it's easy to pick up wrong ideas and I'm glad to bust another one. Here is some information about gassing off chlorine/chloramine by spraying or aerating the water.

    The theory about gassing off chlorine by aerating or spraying it was ok many years ago when only chlorine was used to sanitise water because it gasses off quickly but water suppliers are going over to using chloramine because it lasts much longer in the supply pipework than chlorine.

    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 gets into a pond as a result of not fully dechlorinating a top up will reduce by 50% every 2 hours. E.g. 50% after 2 hours; 25% after 2 more hours and it will be 12.5% of its original level after a total of 6 hours so the level will be less than 10% of the original in 7 hours.

    With the dilution by the water in the pond, and the fact that chlorine halves in strength every 2 hours, if small amounts of incompletely dechlorinated water got into a pond, it wasnít ideal but it would be survivable. However, now that chloramine is increasingly being used, it's a different story.

    Chloramine has a half life of anywhere from a week to 23 days especially at higher values of pH so, if incomplete dechlorination or adding undechlorinated water results in any chloramine getting into a pond today, it could still be at half its strength in 3 weeksí time and, during that time, you will have been adding more.

    That's why I don't recommend any practice of adding undechlorinated water to a pond including a slow trickle and the practise of spraying it in which wasn't even effective at removing chlorine let alone chloramine!

  27. Thanks Ajm, dbs Thanked / Liked this Post
  28. #19
    Senior Member Rank = Kyusai Djstiles999's Avatar
    Join Date
    Jan 2019
    Location
    Forest of Dean
    Posts
    1,098
    Thanks / Likes
    1630
    Syd, quick question but do the DP tablets used for chlorine also read for Chloramine?

  29. #20
    Quote Originally Posted by Djstiles999 View Post
    Syd, quick question but do the DP tablets used for chlorine also read for Chloramine?

    There are four types of DPD tablets (DPD1, DPD2, DPD3 and DPD4) which all measure different forms of chlorine/chloramine but assuming you mean DPD4 tablets; "yes" they do.

  30. Thanks Ajm Thanked / Liked this Post
 

 
Page 1 of 2 12 LastLast

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
All times are GMT +1. The time now is 02:22 PM. Online Koi Mag Forum
Powered by vBulletin® Version 4.2.3
Copyright © 2021 vBulletin Solutions, Inc. All rights reserved.

vBulletin Improved By vBFoster® (Lite Version), © UltimateScheme, Ltd.