Does Crushed Oyster Shell Continuously Raise Kh?

[koiloco]

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.

[Ryan S.]

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.

[soelistyo]

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?

[bekko]

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

[soelistyo]

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.

[mike]

snicker snicker just kidding.

all the oyster shells i used are oysters I ATE! so im pretty sure they're safe.
as to effectivity, they say that you need quite a few hundred kilos of oyster shells for your pond. but i have another theory ... better to have some than to have none.

as to effect on ph, all i know is, my water was 6.8ph before the oyster shells and after 2-3 months it was 7.6ph

good luck!