Gfo question

[gregzz4]

+1 to the above, and I'll add the same ...
Test your output, compare it to your system, and change your media every 4-6 weeks if all is good.
Keep a record of what's happening so you can keep an eye on when you initially need to change it and go from there.

[Proteus]

Thanks everyone.

I tested outlet and It is the same as tank. I'll change it today