You could potentially mix multiple herbicides together as long as you have the correct dilution rates for the products and your timing is still accurate. Just remember that you will need to use sufficient volume with pre-emergent herbicides such as Pendulum 3.3 EC to carry the active ingredient into the soil through the thatch of grass. We would also suggest performing a small jar test before mixing a large batch to be sure new mixtures are compatible.
Pennant Magnum and Specticle FLO are pre-emergent herbicides that can help prevent nutsedge.
We would not recommend using Pendulum 3.3 EC within 6 feet of a well.
It is recommended that you wait at least three months after applying Pendulum 3.3 EC to reseed or overseed your turfgrass. It is also recommended that you allow the turf to recover prior to making an application of the product.