55 gallon freshwater tank. Aqua top uv canister filter Submersible heater 2 air stone Used media In filter from person who I got tank from. Tank set up Monday April 3rd with tap water. Ammonia was zero and ph was 7.1 out of tap using API master test kit out of tap. Added API quick start and api water conditioner to tank on the 3rd along with 15 live plants and driftwood from local aquarium store. (I didnt test again till the 8th) On the 8th ph was 7.2 and ammonia 0 nitrite 0 and nitrate .10ppm. I added some fish on the morning of 9th. Ooooooops I think I gooofed up. Now I was advised to add micro bacteria to tank so I did......... Last night I did water test and p.h at 8.2 way up......wow.... ammonia last night. 25ppm.....nitrite 0 and nitrate 10 to 20ppm. I stopped feeding the fish and stopped with the daily shot of flourish excel I was told would be beneficial to green plants in tank. I figured continually adding all thus stuff can't be good. So today I'm at about an 8.0 for PH slightly down from last night Ammonia .25 to .50 ppm that's the one that scares me. Nitrite still zero and nitrate 10 to 20 ppm. What should I do???? I've read slot about 25% and 50% water changes but not certain if I would benefit from that approach????won't that just delay the cycle by removing the ammonia for the bacteria to eat preventing the aquarium from completing cycle??? Any help is appreciated. I've lost a ghost shrimp but other fish are looking good.