Maybe you have Ammonia at the tap, probably worth testing to see since you have Ammonia readings in the tank and no source. It'll be handy to have that info when you add fish.
For now if you're doing a fishless cycle and adding fish afterwards, my personal recommendation is seachem stability and any Ammonia that is dye, perfume, and suffectant free. Basically look at bottles of Ammonia and if it says any ingredients other than Ammonia it won't work. Dr Fosters and Smith has one and most Ace hardware stores have it. I've always had luck at any hardware store finding it to be honest. I do believe Dr Fosters and Smith is much smaller though so you don't have it hanging around the house. There's Ammonia dosing charts online (Google & pick one lol), dose up the tank (don't add prime within 48 hours before or after) and add Stability. Stability should be dosed daily. I have run a fishless cycle complete with Ammonia and Stability in a week with 2 days of confirmation testing.
Depending on what stock you are planning to put in, you can also do a fish in product such as Tetra Safe Start + or API Quick Start. Those are ones where you add the fish and 12 or so hours later add the product and do nothing for a 7-14 days. No water changes, test results will be crazy if you try so there's no point. I don't like them because I can't test or water change.
When you are fully cycled:
Stability and Ammonia method - you'll dose Ammonia and it will be fully converted to nitrAtes in 24 hours or less. Ammonia 0 - nitrIte 0 - nitrAte of some reading over 0 generally over 5, planted tank you'll likely want over 10 unless dosing nitrogen.
Fish in cycle with product - you will test after your waiting period and hopefully have Ammonia 0, nitrIte 0 and some nitrAte reading over 0. If not do a huge water change and dose again and wait. Fish in can be very hard on any fish, sensitive types do very poorly and shrimp won't survive it.
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