Sweet! Got a gallon of that. I had never heard of that brand before.Do a big water change 75% . And replace the carbon.. add more than 1 sock.
Get yourself some frtizyme 9. It sounds like you need to get some beneficial bacteria in that tank. Fritzyme 9 is the only good bacteris ina bottle. Use 3x recomended dose. They sell 1 gallon bottles on amazon for like 30$ last i checked.
Also dont overdose prime in it takes oxygen out of the water and ive had it kill fish in saltwatse.. they need to put warning lables like that on the bottle.. for fresh water its ok but salt dont overdose.
very much agree with the warning label on prime.