Oil Dri and similar products reduce TDS, KH, etc?

I use Safe-T-Sorb & yes it did drop the KH. My KH was always low even before I started using it so I use baking soda to keep it up.

Can't answer about TDS since I don't test that.

Don't know about the TDS, but saf-t-sorb and other similar oil dri type products will bring down the Kh. This is only a temporary situation though, as the clay does have a saturation point. As a side affect of dropping the Kh, the Ph will also be lower for awhile.

Yes, they can- but it depends quite a bit on the water parameters you're starting off with.

Yes, TDS goes down, too.

It is not removing everything from the water, though. GH remains the same.

Thanks for all the replies so far! What I was thinking is that I could have a container with oil dry that would be used to reduce the KH and TDS for acidic water fish, and which would be changed once a month to ensure continued efficiency. Would this be effective? (my water's TDS is about 173, but I have no clue what the KH or GH is)

Also, where can one find oil dri or similar products?

Wal-Mart where else, tractor supply, auto parts stores