260l Filtration help.

Good evening

I am a new Large tank owner and the first time not using a Kit tank with a Top Filter like my 33L Boyu which now homes my Betta.

I recently bought a 2nd hand 80cm 260L tall tank that came with a non operational Atman CF-800 Canister and also. Via Aqua TSF-450 Corner Internal Filter tat does work. There is not much space for much Media and it it only seems to have Carbon & Floss. I am also running an Airstone but have turned it off for now as it seems to stress the Gourami.

The Tank is currently not overly stocked with 7 Juvenile Angels, 4 Juvenile Blue Rams, 1 Dwarf Gourami, 7 baby Mystery Snails & a Juvenile Featherfin that I rescued.(Not a good fit as he seems to bully at night so I will need to move him)

The Internal Filter apparently only does 280L/H but I am not sure if this is really sufficient as this means it only cycles once fully per hour.

Currently, I have Hornwort & A small Annubius & Bacopa. Only the Bacopa is planted. I have Driftwood (Spiderwood & Rock). Temp at 26.5deg. (I have added a lot more Hornwort since this photo.

I am not sure if the Cannister can be fixed but ut runs 900l/hour. Would it be better and also suitable for the fish I keep or is this Internal a safe option? Also if I can continue using the Internal Filter, what media would be recommended?

TIA