It might be helpful to take a clean uncontaminated small container, take out a little bit of tank water, and put some fish food in that. The next morning, the food will be well on it's way to decomposing each time you add it.
Personally, I did this for a week. I did get ammonia results (pretty low though.) It is very messy. Just really messy. As I stated before, I would do the shrimp in a brand new nylon that you can remove upon completion, before I did fish food.
But even better, would be the liquid ammonia. This is really really simple, so my question is do you think you have an ACE Hardware store anywhere in your vacinity? Because for $1.50 you can get all the ammonia you need, Janitorial Strength 10% Ammonium Hydroxide solution without any suds or additives. And this is easy-breezy easy. Pretty much 1/4-1/2 tsp worked for my tank for about 6 days, and after that, about once a day. The rest pretty much does it by itself, especially if you have an Ammonia Alert sensor in the tank. I test often, but that's because I like to chart daily progress.
If you can, get some already bacteria seeded media from someone else... it'll hopefully keep you from stalling out and speed up the process. I recommend a filter (less likely to carry things like unwanted snails from someone else's tank).
Good decision

. You'll be happy you did, when you can bring your entire school of fish back to their perfect home at once.