So.. Did I lose all my bacteria ?

[SparklyOnTheInside]

Routine clean of a mature tank, rinse the filter (in aquarium water obviously) and there is no yuck in the sponges at all so although it is running it's not doing its job

So I've done a 50% change to be safe and I will get a new test kit asap, I needed to do that anyway.

But will there be any bacteria left on the sponge or am I stuffed? I woul welcome opinions, thank you.

If the filter was running and water was passing through the filter media the bacteria should be fine. Test for ammonia, nitrite, and nitrate and report back. If zero ammonia, zero nitrite, and ~20 nitrate, you're fine. If nitrate is higher than 40 do another water change.

it will be working fine, its just not collected any solids, maybe you have feed a more realistic amount since last clean and its not had to work hard