What 40 Years of Fort Washington State Park Organic Input Does to Pool Surfaces
Fort Washington State Park has been producing organic output from its 493 acres of mature woodland since long before most of the pools in the surrounding residential neighborhoods were installed. The tannins from oak leaves, maple seed pods, and hardwood bark that deposit into nearby pool water are not a seasonal problem that clears itself when the leaves finish falling. They accumulate.Â
Each season adds a layer of tannin staining on top of what the previous season deposited. On a pool surface that has been receiving this input for 40 years, the cumulative effect is a discoloration that concentrates at the waterline, on the steps, and in the pool corners where organic material settles and sits.
In the early seasons after a pool is installed near the park, tannin staining responds to water chemistry adjustments and regular brushing. The pool can be kept looking clean with consistent maintenance. As seasons accumulate, the tannin deposits embed more deeply into the surface layer of the plaster or painted finish. The staining shifts from something that chemistry and brushing can manage to something that has become part of the surface itself.Â
By the time a Fort Washington pool from the 1980s has been sitting next to the state park woodland for 40 years without a thorough surface treatment, no amount of chemistry adjustment will restore the surface appearance because the chemistry is working on what floats in the water, not on what has embedded into the surface layer below.