Simple three species, two reaction network

Three species,  two reactions:

1.  S1 -> S2, Flux J0= k1*S1

2.  S2 -> S3,  Flux J1 = k2*S2

Load the model below and then hit the 'Start' button to run the simulation. Adjust the parameter sliders below the plot to see how they affect S2 and S3.