25 litre new tank

This tank size is too small to keep Cichlids optimally. :fish1:

Even peaceful dwarf cichlids need a bit more territory.

how about a 30l will this be ok if not any idea what capacity?

For a single pair of Blue Rams, a 10gal / 40l tank is the lower limit I think.

Most Cichlids just get too large and are too territorial for smaller tanks.

There are many, many other fish with interesting behavior that are more suitable for tanks that size. Badis, some Betta species and other small labyrinth fish come to mind.