I have a 20L tank with 8 platy's and 1 danio (odd mix but we had a pregnant platy when we got them).
The stingray filter I originally purchased has packed up and I've seen several poor reviews since. I obviously want to give the best care to my fish and would appreciate some guidance from the community on what set up I should be looking for.
Additional tank information; 2 small plants, gravel base.
I would look to upgrade to a larger tank - 20L is much too small for what you have. Go for at least 60L and see if you can get something with a filter included - Juwel Rekord springs to mind. Check eBay, Loot, etc., as tanks can be had in excellent condition for peanuts second-hand.