My tank stinks!
 

I have a 75 gallon tank. It is very clean and maintained, but about 3 weeks ago I noticed that it smells really really bad. So bad that if you leave the door closed in the room that it is in for 5min and then open it the whole rooms smells. Is there anything I can do or is there a reason why all of a sudden my tank smells so bad?

Sounds like you have some ammonia buildup in your gravel. You should do some gravel stirs, as well as gravel vacuuming.

It would also help if we knew your water parameters.

do what cody says and change the filter

By filter, I hope you mean filter cartridge/sponge.

if you got snails, make sure they're all alive.

What type of filter do you have in there?

i wouldnt change the filter pad until it was literally falling apart, if its clogged swish it in tank water that you take out in a water chage and if your still in the "cycling" stage i wouldnt touch it at all, period.

yes thats what i mean

This is also a case where carbon might help!

I tested the water and its fine. I have narrowed it down to that it is my filter that actually stinks. I replaced the filters and the filter still smell really bad. There is carbon inside the filters, I run Penguin C filters. Any idea what could be the cause of this?