why does my fish tank water smell so bad?

[Sydney O]

About four hours ago I put four platies one large pleco my medium sized pleco and one gourami in my five(5) gallon tank. The smell just started about thirty mins ago and I have no clue what the prblem is I checked the pH and it was alkaline(that was a dip stick) then I checked it again with a liquid test and it was 7.6 which is supposed to be the best pH for my platy fish(because they are live bearers, I don't know if a gourami is and if someone could tell me that would be cool). For my filtration system I use an Aqua Clear 20 it cycles 100 gallons an hour and I have an air block in the back and I hve a crystal clear tank. I also need to know if it will be ok to add my other chemicals( Nutrafin Cycle, Waste Control, Aqua Plus, Jungle brand Aquarium salt, clear water(which also removes odors and cloudiness,but I want to be gentle with my new fish) and my API brand Ammo lock) I also checked my ammonia(NH3 and NH4) with a liquid test and it was .25 so I have no clue what else I could do I just want to know what I can put in there to fix my problem and be gentle on my new tank fish. The Clear water stuff makes my whole tank turn purple-ish pink so idk what to doI also have other chemicals(Seachem neutral regulator(pH stuff) Tetra Aqua Easy balance with Nitraban, Tetra Aqua Aqua safe (tap water conditioner, is just the same as the Aqua plus), and Tetra Aqua Algae control, API Liquid fungus cure, API super ICK cure, Tetra Aqua parasite guard, and Jungle correct pH) so if I need any order to put these chemicals in, the amount of time to let them settle and to add more would be nice, just give me some kind of order and no I do not have too amny fish in too little a space. I think it could be my plecos that smell, because I had lost my previous goldfish and when my pleco was alone he gave off some vile smell that was NASTY so if I could get some HELP that would be nice. PLEASE HELP ME