Hi Guys,
Thanks to many posts from you and others on this and other forums covering various trickle tower filters - and speciallly to great web site of Syd aka Manky Sanke - link is here - http://www.mankysanke.co.uk/html/goo...de__pt_16.html - I went on to build my slightly modified version of denitrifying trickle tower combo - if interested, attached pdf covers it with pictures and comments.
For more details on how it works in real life you may look at my posts here - http://www.koiforum.uk/water-treatme...wer-combo.html
Really happy with its performance - if this post may help someone else to DIY your own version, please share with us your own experience!