Concentrated solutions of chlorine degrade and the degradation rate is roughly proportional to the square of the hypochlorous acid concentration. If I assume you added the maximum amount of Trichlor that would saturate the solution, so around 8 ounces weight of Trichlor (about 11 ounces of product) in 5 gallons of water, then that would be around 11,000 ppm FC of low pH water (around 2.8) so would degrade rather quickly. You would probably smell chlorine gas from it. The chlorine would degrade into hydrochloric acid and chloric acid and when it does the remaining Cyanuric Acid (CYA) will precipitate (or coat the container) since it is less soluble than Trichlor.
If you did not dilute by as much, then you may not see the CYA precipitation, but the chlorine will still degrade, though not as quickly. Generally speaking, you want to add such concentrated chemicals directly into the pool water slowly over a return flow to get the most dilution as quickly as possible. Pre-dilution should not be necessary and can be detrimental especially for granular Trichlor.
