Re: New Fluval Roma 240 tank!
#4
Funnily enough, I went from a 90l tank, to the Roma 200 about 3 weeks ago, with very similar concerns to you!
I plopped the new filter in my old tank, and ran it in there for a week.
I saved ALL of the water from my old tank, in 5l water bottles, and 40l storage crates. (One crate held fish whilst the old tank was removed and new one put in situ, another crate held plants.)
I used all of the old gravel, and 5kg of new gravel.
It was actually remarkably straight forward. No fish have died since the transfer, and I've added a few more. The water chemistry has been very stable, pleasingly.
I bought new plants from Plants Alive - 15 potted plants. Some have rotted back, my plec has "gardened" - swooshing through some and knocking them from the gravel... but the larger-leaved plants are doing OK. I took them out of the pots, but kept the fibrous stuff round the roots, burying it all in the gravel with a squished root tablet.
Good luck!