Yeah that's the airstone all covered in muck.

It was a weird consistency, hard to wash off. I gave all the components a good long soak in h2o2 and scrubbed everything.

This week I'm not using any great white and I'll see what happens.

The plants couldn't be happier. Lots of strong white roots starting to show out the bottoms of the net pots.

What ever it is, it doesn't seem to be hurting the plants.

Thanks