Hey Jan,
Be extra careful with anything labelled potting soil. I have found that every brand that was labelled potting soil had something in it that was not wanted. That's why I still recommend black earth.
As for the screen top you can buy screen tops at the pet store that are perfect fit for most normal sized tanks. This will allow the cord out through a corner, and the newt won't be able to escape with it. Or you can make your own and drill a hole in the frame just large enough for the wire and nothing else.
As for putting something on top of the soil, some moss may be nice but make sure it is only in a small area. Sometimes moss can bother some salamanders due to being acidic, so without knowing which kind of moss you would be collecting it's hard to say. Better to put it in a small area so the animals can choose to go on it or not. You could also place whiteworms into the moss, and from what I have read they will multiple in it, leading to food in the tank as well as something that will help break down organic waste. I do something similar with springtails in the soil of my tanks. The bed-a-beast coconut fibre I have used, but many people think it should be avoided since it is not a natural substrate that you would find them on. If you wish to use it though I have used it with great success, and others that I know mix it in with soil so that the water is retained better. I no longer use it though and use strictly black earth in all my terrestrial tanks.
If you're setting up this elaborate of a tank for CFBNs it seems a pity to keep them, as adult CFBNs are usually completely aquatic. There are other species that could make use of a beautiful land and water area though. Those may make more use of your tank.
>>Rob,
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>>Thanks again! I found some potting soil with no perlite and put that in yesterday. I planted more polka-dot plant, more creeping fig, a button fern and another fern. I also glued the tillandsias onto the cork bark. I went ahead and put in a thin layer of gravel in the water part, put in conditioned water and set up the Duetto filter with a possible (may be changed) waterfall. This morning everything looks fine....except the tank is fogged up! I had an old hood on it with a flourescent gro-light....I think you're right about the screen top. Only thing I'm worried about is how to get the cord from the filter out of the tank without making a hole big enough for the newt.....I'm debating whether to put native moss on top of the soil, or bed-a-beast. Any suggestions, anyone?
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>>Thanks again!
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Hope my opinions help,
Rob