If your doing a fish in cycle look at products like Seachem Stability or Tetra Safestart. They’re a bacteria colony in a bottle, they can put you months ahead on a fish in cycle. Dose some, keep up light feeding of fish and dosing the stability etc, add 3 more ember tetra at end of couple weeks, keep dosing and go into a holding pattern on fish for about 3 more weeks keeping up on light feeding and monitoring ammonia, dose extra stability if you see a ammonia flare up over .25ppm. Monitoring your tank constantly in these 1st few weeks is very important.
Also check PH of your water your using for water changes and in tank. Ammonia exists as ammonium below 6.8PH, it’s way safer to your fish than ammonia. If your change water is above 6.8-7PH, when you change water you will get surge of ammonium converting to ammonia, ammonia is bad juju, ammonium in low amounts is fertilizer. Always let your change set in a bucket for 24hrs to absorb gases and normalize to atmospheric gases (which it can’t do trapped in a water pipe or even a gallon jug), let water breath before you use it, that way PH of your tank and change water will be about the same so you won’t get any ammonia surges.
Basic rule is the higher your PH the more lethal ammonia compounds become and more you have to worry about it. A level of .25ppm at <6.8PH in fresh not a show stopper but it would decimate a brackish or saltwater tank up at 7.6-8PH.
I would also suggest you get a some almond leaves or sera super peat or spaghnum peat and lightly treat your tank and change water with them to add extra humic and fulvic acids at this point. Natural PH regulators and also great softwater conditioner for fish like embers and gourami. This is my water prep bucket for my 7gal betta/neon/ember tank, light yellow tint.
I would also warn you about going bare bottom in tank. Usually the substrate layer is main bio-filter in freshwater tanks. You’d be much better off with .5” layer of pool filter or play sand than going bare bottom. The amount of bio filtration a good substrate layer can do will far exceed what any filter will do unless you’ve got g’normous canister full of bio media. A average sized hob filter like yours won’t even come close to doing what a good .5” sand bed will do in your tank as far as surface area to house a substantial bacteria colony.
I run AC20 on my 7gal also but I would never attempt a betta and 11 tetra without a substrate bio bed in tank. You also need a sand bed if your going to keep Cory, that’s what their barbs are for, rooting around in sand, picking up waste and turning sand over.