Your going through a fish in cycle and your high ammonia is due to insufficient PWC
's since your don't have any bacteria established. What fish are in the tank and how many? That's important .. some fish have a larger bio-load than others. Start on 50% PWC
's until you get your ammonia to below 0.25% ... closer to 0% Trash any test strips ... unreliable at best .... if you don't have one already, go with the API test master kit.
DO NOT replace the filter cartridge again ... that is where the majority of the bacteria will ultimately reside. By throwing it out, you essentially are starting over again. Only replace those cartridges when they are literally falling apart. Just swish them with tank water during PWC
's to clean of solid waste debris. A white cloudiness is indicative of a bacterial bloom which is normal and are signs of bacteria colonizing into your tank, then they'll make their way into your filter.
The only chemicals you should have to add to your tank are water and a conditioner like seachem prime. Let us know the following info so we can better help you.
1. Tank stock
2. Type of filter / filtration
3. Water Temp
5. Ammonia, Nitrite & Nitrate.
The API test master kit will tell you numbers 4 & 5.
75g Planted Barbs Denison, BlackRuby, Tiger, Albino Tiger, Green Tiger, Cherry, Gold, Checkered, Odessa.
NonBarbs Cardinal, Neon, RummyNose, Bloodfin Tetras, Z. Danios. 1RTS. Amano, Bamboo, Ghost & RCS. 20g Long Shrimp Tank RCS, Tiger, Amano.