A new phosphorous (P) reaction and transport model suitable for conditions present natural or treatment wetlands is presentd. One of the main strengths of the model is that the complexity of the biogeochemical reactions is user-selectable. The level of user-defined complexity can range from the simplest settling-coefficients to complex ecological cycling. In general, the P model contains transfers between stores. Samples of strores that can be included are soil, water column (solutes), pore water, macrophytes, suspended solids (plankton), biofilm. Example of transfers are growth, senescence, settling, diffusion, etc, first order, second order and Monod types of transformations. Model applications are demonstrated with mesocosm and field-scale data from wetlands in South Florida.