Changing gravel

[bignose]

I am currently changing the gravel for my fahaka from brown to black.
I have a eheim filter with bio substrate media that has been running for 4 months.
Will this substrate be good enough for me to change out the rock out all at once?

[The Bruce]

last time i changed gravel i put a lot of the old gravel in mesh bags and threw them on top of the new gravel, then took the bags out two weeks later, worked for me

[Nick]

I changed an entire tank from a ten gallon to a 15 gallon, the only things the same were live plants and one decoration, just with the dirty uncleaned filters from the ten gallon going over.

[StormySkiez]

When I changed out all my gravel in my 10g at once I had a mini ammonia spike after the fact. One water change resolved that issue but I wouldn't do it all again at one time.

[Nick]

I did have two filters on it, so they had a lot of bacteria.

[bignose]

Thanks everyone for the help.
Don't want anything to happen to Tubby!!