Thanks. So far the tank copes very well. It has a far longer light period than it should, with natural light all day (though not all that much completely direct) and LED light from 1.30pm to 9.30pm. The LED is a single 12w (4x 3w) Cree lightbulb in a lamp fitting, with a dimmer. I've actually just turned that up to full as I feel that the foreground isn't getting quite enough. There's less light in the windows now the season has changed, though I have taken down some tomato plants that were blocking the sun before. So far the floating plants seem to keep everything under control, though recently they've been telling me that some ferts are needed.