The test kit is not the best but is usually reliable. I have found that it is easy to make mistakes with it though. You may want to compare your test with another just to make sure. You can also take you water to most LFS to have tested.
The good news is even if you add filtration and it does not solve the problem, it won't be a waste because of your growing stock it will be eventually needed.
So if it does turn out that there is no ammonia problem as you claim, I would remove the rocks that you aquired from the creek and see if the water gets clearer.
The good news is even if you add filtration and it does not solve the problem, it won't be a waste because of your growing stock it will be eventually needed.
So if it does turn out that there is no ammonia problem as you claim, I would remove the rocks that you aquired from the creek and see if the water gets clearer.

if you know so much why dont u share it with me.