My Arcadia Arc Tank

Good evening forum,

Ive had my Arcadia 35l tank for a while now, it currently has two mollies and two guppies who are doing extremely well in my tank, ive had no problems with them to date.
Ive been looking through the forum and ive had a few ideas for my tank that i thought i would run past for some advice before i mess it all up as this is the first time ive had a fish tank.
Ive done some research and found that the filter that comes with my Arcadia tank isnt the greatest, i have always wondered if it was that great, i currently do a 20% water change every week. I was just wondering if there was any other filters on the market that would be better and more suited?
Im more than willing to get rid of some of the ornaments that ive got if it means that i could get some plants and some more fish, if my tank is big enough? if i can what kind of other fish would be best suited? i wouldnt mind some more guppies as i think the ones i have look awesome
Knowing me, ive forgot to ask something so i might have more to ask lol, but thanks in advance for any suggestions

I have a eheim external canister filter on my 180 litres and recently added an eheim liberty HOB as well. The Eheim liberty HOB filter would be good if you can stand it hanging on the back - although it can be a little noisy as the water "splashes" into the top of the tank. Perhaps a fluval internal? I've read quite a few good things about them, but again it depends on your preference. Filters inside the tank in my personal opinion look ugly.

AllPondSolutions or APS... Have a quite decent small external filter that would suit your needs. If you type All Pond Solutions it will come up with their webpage on google. The product I was looking at is called Aquarium External Filter 150 L/H. It's a great price at £20. A lot of people on these forums have recommended their products. Also it is rated for 70 litres which would be about right for your 35 litre tank. (I always try to go about double/triple what the manufacturer states as OK).

Also, you could run that external in conjunction with what you already have not only to allow the new filter to cycle, but also to give you better filtration overall.

Just a few options for you there.