I was at a breeder yesterday and we were talking about how I take care of my goldfish and he told me to put corals inside my cannister filters to stabilize Ph.I wanted to check from you guys first if it is safe to do so.Thanks for any input

Sure it's safe. Need to be sure and rinse it well as it's pretty sharp stuff. It dissolves when the pH falls below 7.4 and increases both carbonate hardness (KH) and general hardness (GH).

What's your pH, KH and GH in the tank and out of the tap?

Great idea. Can I get them at any fish store? Do they go in before or after the filter pad? Are there any downside to using corals?

It works great!! I used crushed corals and some shells but the corals are not the very sharp type. They are mostly rounded and had smooth surface with lots of tiny pores in it. The PH is maintained at about 7.3-7.4 without adding BS for almost a week. GH is also increase to about 100ppm and the tank water is super clear. I soaked the corals in tap water for 24 hours before use and no sings of contamination in the tank.

Thanks everyone for the inputs


I do not have test kits for kh and gh Ph is 7 from tap and from tank is 7~7.5.

Crushed coral or oyster shell wouldn't hurt as I'd bet you'll see your pH slipping down over time.

Thanks Dataguru
I already have the corals but I haven't put them yet.So should I crush them?Or will it be okay to put them as they are?They are small

The key is to have enough there to dissolve when it's needed--a lot of surface area and lots of water flowing thru it.

Thank you very much!I really appreciate your help

You're welcome.