I'll let you all know when I recieve the glassware and measure up. The closest gets a copy of the latest 'The Aquatic Gardener' magazine, if they're interested...
It's important as I've modified my Juwel hood to incorporate the lily pipes.
I'm hoping 'x' is long enough to allow the 'lily' to be submerged sufficiently.
If not I'll take the hood off completely, add a glass centre brace (as the regular brace is integral to the hood), and use an overtank luminaire.
I found that due to the suckers sticking to the outside of the tank that most of the U goes through the holes meaning that you should definately be able to totally submerge the lily.
The question would be more a case of how high can you get them if you choose to use them to aerate occasionally as I do or even have them constantly providing extra O by having them 2/3 in 1/3 out and putting in extra CO2 as I was doing previous.