Have you been keeping an eye on your ammonia, nitrites and nitrates?
Do you have an idea of what GH and KH you want to run the tank at?
What substrate are you using?
Generally speaking, shrimp do best with stability. That tank, especially with 50% water changes, will not be that stable for shrimp.
If you don't have experience keeping shrimp, then I'd recommend starting with a 10 gallon tank, as the water parameters, and temperature, will be more stable. The smaller tank can be used to grow plants in.