To be honest, I think at the moment, its best just running the 205 with the seeded stuff in it. Remove the zeolite, and just keep an eye on the levels.
I say this because...
It goes Ammonia --> Nitrite --> Nitrate.
If you have nitrite in your water, then there is some breakdown of the ammonia... Which is good, as it means the bacteria (1st stage - Ammonia --> Nitrite) is working.
As soon as you have nitrite in the water, the bacteria (2nd stage - Nitrite --> Nitrate) that break that down will be cracking on with that job, and mulitplying too. So, you are doing well! Just make sure the zeolite is gone, so the 1st stage has something to break down, and also to keep the second stage in Nitrite.
When you have a stable tank, water changes are used to dilute the Nitrate as there are no filter bacteria to break this down.
There are other ways to reduce nitrate in the water, but for now, weekly small water changes should be enough in your situation.