I've been gone a while! I thought the tank was a jungle before, it's more so now! The tree looks great.
Not quite sure what more you could do. I would group the creeping Jenny together, it's a bit spread and random for my taste, but that's JMO. I also, just see a lot of the same shade of green, but that's probably the photo. I'm sure it looks different in person.
Yeh I would agree with Llj, lots of green Also is the moss lawn on doing so well anymore?
One suggestion, I wonder if removing the vals might help, being able to see 'through' the tank and out the other side might open it up, its got a very enclosed feel about it at the moment.
Poss also have either the sags or hairgrass on both sides? I.e. so they match, think the semi-symmetry might help? The fairgrass also has more of a 'woodland glade' fell to it so think it might work better with the tree and moss carpet combo
If you do fancy a change, what about a minimalist look take all the plants out but keep the tree and carpet the tank in HC, glosso or hairgrass, should look fab . Like Sam suggest's a woodland glade, with a tree hargrass and a cluster of small rocks.
I do love that tree FKNM, each time I see it, it gets better. Simon's suggestion is quite a cool one. It'd be like the village green, just one tree and a field of 'grass', that would look cool!
The pink adds a nice splash of colour. Re-scaping already! Lets hope in a months time it looks even better and you are persuaded to re-think that one!
I really like the new look! Thinning the vallis along with the blue background gives it more depth.
For the gravel in the front that you mentioned gets mounded up, just siphon some out so that it's much lower in the front -- maybe so it's more level with the grassy area? I think it would give it a more continuous look.