I think your filter is rated by the manufacturer for a 10g. So even if it worked as well as they say, it's undersized for your tank. I would suggest you get an Aqua Clear 20 or 30 & use the Aqueon for mechanical filtering without the prefilter. It will need cleaning more often that way but it's just a secondary filter. The pads should be fast & easy to clean every 2 weeks when you don't need to worry about the beneficial bacteria. Just don't clean both filters the same week. You can wait until the flow slows a little or do it regularly.
Run both filters, don't worry about "seeding" the new filter, it'll occur naturally. Wait a couple weeks for really cleaning the Aqueon. You might use the prefilter on the AC. I "think" ACs come with 2 sponges & a bag of "bio bits" (it's been a long time since I had a new 1). I would do sponge, bits, sponge. IF you need floss for fine particulates, I would do 2 sponges, floss then bag'o'bits to hold it. Use enough floss so it's 1/4 inch after its wet & running in the filter. More doesn't help, it's the bottom part that gets gunked up. It can be rinsed in running tap water & reused several times. Just buy a bagful & you'll be set for quite a while...I think I may be on my second bag floss in 40 years, lol, but I rarely find a need for it.
I'm a strong believer in vacuuming substrate anywhere there aren't plant roots. Pick up the decor to vac under it once in a while, or alternate vacs if you have lots. If you have piles of rocks, well, much less often than a hunk of wood.
Your fish may think they're always hungry, they don't have much else to do, lol. 2 very small feedings/day is ok for juvenile fish but adults need less. The old saying is feed the size of their eye, say 3 or 4 bites of food. Fasting 1 or 2 days/week is fine. Keep in mind the more you feed, the more they poo or the more you need to vac out uneaten food. & obese fish are no more heathy than obese people, they don't burn off too many calories in a small tank. Some fish will overeat, others will strike food but they don't really eat it or spit it out. It's just a survival in the wild behavior, eat while you can...