hi BigC,
take the plunge and get another tube in there.
it was me who started the original thread (link above) if you clich the "check out my fishies" link in my sig you'll see the tank 3 weeks after upgrading.
there is pics of both the rekord 60 and rio 180. both have been upgraded. (details in "my profile"
PM me if you need any advice on the "bodge job" and yes i am left with a 1 inch wide feeding slot but with the purchase of tongs etc, you dont need to get your hand in.
well worth the effort if you ask me.
PS: Vallis needs a lot of light to thrive, i remove at least 1 foot from every leaf weekly in my 40G. CO2 makes a big difference as well.