Thanks for the kind comments guys, I'm really pleased with it. I don't think it would look anything like this if it wasn't for the forum, I've read and learnt so much here.
Fingers crossed that it stays green and that the shrimp thrive.
Diwu, it was kind of a white flat jelly. It started covering the wood where it was cut, then came out from the insect bore holes it had. Then it just started to get everywhere. I read up on it and I think it was just water mold, but as I didn't have anything in the tank to eat it, it was just going to spread.
I still have a tiny bit on the suckers that hold the spraybar and filter input, I think the shrimp will deal with that once they find it.
Cheers though, I will bear it in mind for the future