crushed coral alternative?

[DG22]

My water has a ph 6.8, kh 40 ppm, and gh 300 ppm. I tested my water this afternoon to find that the kh was nonexistent. the ph slipped down to 6.4. I went to both towns nearby to find out no pet stores have crushed coral. As I was looking around on the internet while in town I found "oyster shell poultry treat" at the tractor supply. The ingredients say "oyster shell and coral calcium, clam-coquina like shell." 

Is this pretty much the same thing as crushed coral for aquariums?

[modified lung]

I buffer a few of my tanks with asian clams shells I found in a river.

[nabokovfan87]

On 3/29/2022 at 7:53 PM, DG22 said:

went to both towns nearby to find out no pet stores have crushed coral. As I was looking around on the internet while in town I found "oyster shell poultry treat" at the tractor supply. The ingredients say "oyster shell and coral calcium, clam-coquina like shell." 

I would highly suggest just ordering it online via the coop.

Other options include just using plaster of paris, pumice, and seiryu stone (with heavy white marble patterns.