Well, other than your Omega 1 catfish pellets, I don't know those foods or filter. pH doesn't matter too much for most fish unless it's really high or low.
Soon, can you take a water sample to petco & write down those "other" numbers. We need to know even if it's just a "range" .
Do NOT leave food in the tank for more than 24 hours. It will break down into several bad water parameters. You need to step up your maintenance regular game plan. Check out the top of the Newbie forum for more cycling info...& change lots of water as often as you can, every day would be good, every other day ok. But you need to test to know what's happening. Plan to buy a Master Test kit soon so you can test at home often or go to Petco at least twice/week. Remember, we need real numbers, not just ok