Being in the construction industry since the early ’90s, I have learned that equipment and “stuff” doesn’t necessarily work the way it’s supposed to. Being in the water garden or pond business since the turn of the century, this century of course, that ideology was re-enforced.
My observational theory is that “environmental” conditions across the United States have stressed much of the filtration on the market or in use today. The standard “active” mechanical filtration, that uses media, whether poly fiber, matala, smart silk (netting) or bead, may be subject to heavier sediment loads than normal. Even “passive” bog systems like “natural wetlands filter” systems have been subject to stresses.
When doing local trade shows or local pond seminars, the question of filtration seems to come up quite frequently. The majority of the marketplace is rock and gravel, pond “in a box” type stuff.
Filtration is really the part that installers and homeowners alike do not understand. If we are to believe the marketing hype that the “filtration” doesn’t need to be cleaned except once a year or seasonally, then our ponds are going to have difficulty.
What field experience has taught me is to keep an eye on the filtration system and keep on eye on the environmental impact on the ponds in the neighborhood. In urban settings, the “guidelines” for filtering your pond may just have to be modified to fit conditions.
Outside influences, like construction sites, are events that put a lot of “dust” in the air. In those areas impacted by agriculture, it can be more seasonal with dust during planting or harvesting. Applications of nitrogen and fertilizers to the fields can affect the environment in your pond as well. When a filtration system gets stressed, channeling occurs. Water will take the path of least resistance. It finds its way around the filter matter and begins to recirculate without filtering out the debris or sediment or nutrients.
When the water comes up in one place, in a filter/fall box then it is time to clean your filter “mats.” The same situation can occur in a “natural wetlands filter” where water comes up in one spot, like a spring. If filtration does its job, it will remove sediment from the water. The mat shown in figure 1 is a poly filter that had been cleaned 10 days before.
The homeowners comment was “It can’t be channeling; I just cleaned it a week ago.” The problem was not the filter, but the amount of dust/silt that was being deposited in the pond filtration system from construction going on in the other half of the development, three blocks away. The smart silk (figure 2) was cleaned two weeks before, during planting season in an agriculture area. This filter unit comes with a 3 back drain so emptying the fall box is somewhat more convenient. The Matala filter resembles a pile of silly string (figure 3).
This mat had been cleaned two weeks prior; the dust or silt was due to a road project a block away. Matala filters come in different densities so you need to make sure to match the filtration size with the application.
No matter what type of filtration you choose, always match water flows, filtration application and filter matter, whether fall, bead, or bog. In many cases listening to the pond will save you time and your client’s money. Before you decide the system you’re working on isn’t up to snuff, listen to the pond; it will tell you whether you need to do more or less of what you’re already doing.