When to change carbon?

[fio1022]

Hi all,
Sorry to say but I just treated my tank for flatworm with flatworm exit by Salifert.I use fresh GAC only in a canister filter which I run 24/7.
Howlong should I use this batch of GAC?Should it be disposed or is it still good.I was figuring on changing it out tomorrow but don't know if it is necessary to do so.
I must say this product works very well but the directions are somewhat vague...
Thanks

[bertoni]

If you want, you can buy a carbon test from Salifert that'll help you detect when your carbon has no more life. Once it's adsorbed all the junk it can, it needs to be pitched. How long that takes depends on so many things that I just replace it every month. I use about 2/3 cup for a 29g tank, if that helps any.

[fio1022]

Thanks for the reply.
Since i don't have a carbon test kit,Do you think I should change it now?I usually change it about once a month.
I'm just concerned about the toxic effect of the dead flat worms that I can't see or able to remove.

[bertoni]

I would say change it, since you're using the FE.