The thing is with shrimp is once there is no ammonia source the bacteria die out and there's another ammonia spike from the dying bacteria or so I heard personally I had clowns and sw ghost shrimp and dr tims bacteria but I put that in a month after the clowns
Actually, that's a common myth spread around various aquarium forums, both fresh & saltwater. Scientific studies have shown that the nitrifying bacteria Nitrosomonus is extremely resistant to ammonia starvation and can last up to a year without any ammonia at all and instantly respond to the addition of ammonia.