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Does Crushed Oyster Shell Continuously Raise Kh?

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  • Does Crushed Oyster Shell Continuously Raise Kh?

    I am installing my RO and have 2 quick questions.

    Oyster Shell is a good Source for KH buffer, but once put in the pond.

    does oyster shell ALWAYS increase Kh or It only releases the carbonate when there is more acidification to neutralize?

    ALSO, what do you use to REBUILD missing minerals in the RO + tap water mixture?

    Is it just the Koi Clay stuff?
  • #2

    Originally posted by koiloco
    I am installing my RO and have 2 quick questions.

    Oyster Shell is a good Source for KH buffer, but once put in the pond.

    does oyster shell ALWAYS increase Kh or It only releases the carbonate when there is more acidification to neutralize?
    It requires acid to dissolve the shells. Like Lithaqua or similar products. It dissolves and releases GH and KH.
    Originally posted by koiloco
    ALSO, what do you use to REBUILD missing minerals in the RO + tap water mixture?

    Is it just the Koi Clay stuff?
    Tap water should contain some minerals. RO removes those. Mixing should replace. The clay products add minerals and compounds that aren't normally in tap water.

    Comment

    • #3

      Oyster Shells and KH Buffer

      Oyster Shells really are the best: they can only disolve in the presence of acid (carbonic acid resulting from filter activity): calcium carbonate is really difficult to dissovle without the presence of acid in the water.

      The resulting pH will be in the 7.4-7.6 range (in other word ideal for most koi keepers).

      Do not use Baking Soda as it will induce wide pH changes.
      Arthur

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      • #4

        G.E. Merlin R.O. Unit

        Thanks guys!

        I have a lot of oyster shell!

        As Jason said oyster shell also increases Gh (Calcium), is the amount significant enough to make the water HARD again?

        Comment

        • #5

          The crushed shell used for chicken grit has a lot more surface area per volume than whole shells. In rural areas, it is usually available at the local feed store.

          -steve hopkins

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          • #6

            can someone help advise me how much oyster shall to use? have a pond around 15T plus 5T filter, thinking of using oyster shell. they're pretty costly here.

            Comment

            • #7

              my brother uses oyster shells in all his cichlid aquariums and more so coral sand. hes got about a hundred so hes always buying the stuff, he says it works fine to begin with but does lose its "oomph" after many water changes, dont know what this has to do with the relationship of acidity. pretty sure cichlids like it hard.

              i since told him to use ag lime mined from limestone. can anyone tell me what limestone comes from??/
              well thatd be what i would go with unless you wanted the oysters for bacteria homes as a biofilter..
              though surface areas not so good if your lacking space and if its not prefiltered it will build up with stuff in all its recesses. myslef would go with lime and a test kit to check the level, you might not be able to just throw in a certain amount of shell and expect to leave it be. ive seen it done with success and no one ever checked the pH but thats not to say it was operating within the parameters.
              anytime you change all the water, just put the right amount of lime in instead of wondering. i use about 4 grams per hundred litres and its simple as.

              as for the ro water, whats wrong with a bit of salt. like seasalt and not table salt.
              last time i read up on salt i think i found there were about 35 ingrediants in there.

              Comment

              • #8

                The good and bad of oyster shell use in Koi ponds. Oyster shells (sold as chicken grit in may farms stores in the US) have there place in ponds, but are not a fix all solution, relying on them may leave you a pond of dead koi. They desolve, but VERY, VERY slowly. They are great as a treatment for acidic source water. If you stream source is low PH (like in a Japanese mudpond), or if your well or tap water is acidic, running this water though oyster shells will get the KH and PH up some before entering the pond. Running pond water over them in a closed loop koi pond will accomplish little. What works in a typical high end pond, say Concrete, large volume, low stocking rates (and thus low bio load), and ponds that are sometimes partically covered doesn't always work in other ponds. That liner pond with a higher stocking rate that gets gets rain all the time with a KH of 0 and PH of 4.0, along with continued use of the KH by biofiltration, is a PH/KH crash waiting to happen. The KH/PH crash and poor QT setup are responable for the most of the Koi deaths I see personally. I also run Shower/TT filters, and aerated moving beds, some of these powerfull bio filters are said by some use "use" KH faster. Before I knew better, I tryed the shells and another crushed coral (said to desolve much faster than oyster shells) in a pond with a source of KH 80 PH 7.6, and had a KH/PH crash about 3 weeks later. I now maintain with KH 120+ with baking soda. Another think to consider is that oysters harvested in different regions may vary in content, so what works for someone with a different source may not work for you. Also the "dust" may give you false hope for the first week of testing as it desolved quicker.

                Ryan S.

                Comment

                • #9

                  Ph crash in Ryan's pond

                  Hey Ryan,

                  What is your stocking level and Ph before the crash?

                  During the 3 weeks before the crash, did you even change water at all to supplement new Kh?

                  how many oyster shells you had in the pond at the time?

                  I just wonder because if you did 10% water change per week, could this have not happened?

                  Please share your experience

                  Comment

                  • #10

                    At the time 8 2yr olds (averge size ~20"), two tosai ~4-5" in ~3500gallons. I'm not sure if Graham posts on this board but his experiment/records match what many others are seeing.

                    Comment

                    • #11

                      Quite surprise

                      I am really surprised.

                      My pond is about 6000, Liner. I have about 15 - 14" and
                      20 - 6 to 9", 2 - 21".

                      I changed about 15% of water weekly.

                      Kh from tap is around 120ppm.

                      Pond Kh is rock solid 80ppm at Ph 8.1 all the times with my weekly water management.

                      I did try 1 time not to change water for 2 weeks to see if the Kh would drop but It didn't.

                      I wonder if my GRAVEL filter does contribute to the KH stability???

                      I am installing an RO unit to bring down PH and TDS by mixing RO + tap water. That's why I am inquiring about oyster shell used as Kh sources to prevent Ph crash.

                      Let me know your input.

                      Comment

                      • #12

                        Your source water is great, 120 KH is great and something few of us have out of the tap. Rain here on average is a PH of 4.2, KH of 0. Calcium carbonate has a solubility of roughly 15ppm from how I understand it. I think in Japan most of the oyster shell use in on flow thru systems that are indoors. Magnesium carbonate is much more soluble, so the individual source of shells my effect there usefulness. Whatever works for you. In my pond, my water, my filtration (Bead, moving bed, shower) I consider it safe to run KH at 120+ and the best option to maintain these levels is baking soda for me.

                        Comment

                        • #13

                          measured my pond's PH today. it's 6.0 (gasp). perhaps the recent rainfall had something to do with it. KH is 5.0. i've bought 35kg of oyster shells (don't know the market price but i had to, excuse the pun, shell out USD120 and that seems pretty steep to me), going to dump them in my final chamber above the mats. is this sufficient for a 15T pond + 5T filter?

                          Comment

                          • #14

                            Darn soelistyo! At that price there should have been nice plump oyster meats inside the shell. You know, any type of shell will do the same thing - manilla clams or whatever they eat in your area.

                            You know, the shell is going to take a while to work. Adding baking soda is frowned upon by many here because it is an artificial crutch and can cause the pH to change too rapidly. However, this sounds like an emergency, or nearly so, and might provide more immediate relief.

                            -steve hopkins

                            Comment

                            • #15

                              thanks for the tip, steve. i'm changing 40% of the water as we speak, while doing the regular cleaning maintenance. sure hope that helps. koi (touch wood) so far acting normally.

                              yeah, it thought it was a lot of money to pay for some shells, but i was worried about just using any kind of local oyster shell for fear of running into some contamination problem. i think i heard my wife stiffle a laugh when i told her i'd bought oyster shells that were imported from Japan. The vendor (our local sakai agent) said he only brought 2 cartons in (35 kg each) cause someone placed an order for 1, he'd be out of business by now if doing just oyster shell imports as they're hardly worth as much as the freight and clearance charges. Apparently the ones made in Japan undergo some kinda of UV treatment to ensure it's sterile. i can hear the sniggers even as i type this, but what's a guy to do i live in Indonesia and that's as good an excuse as any for being paranoid when it comes to using anything locally sourced, for the koi pond. you just never know what might happen, and that's just too scary for a rookie like me who might not be able to respond to unforeseen circumstances.

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