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GRAVEL FILTERS

Gravel filters are built on site using rubber liners, protection fabrics, slotted pipe assemblies, plants, and lots of gravel. They have no pre-defined shape and become part of the pond landscape. There are two basic designs designated by the direction of water movement: downflow and upflow.

TYPES OF GRAVEL FILTERS: Downflow gravel filters are used on the suction side of a pump and are usually built at the bottom of the primary pond (see A LILY POND for an example). A protection fabric is laid over the pond liner, a slotted pipe manifold is installed over the fabric, and the manifold is covered with a layer of pea gravel at least twice as thick as the pipe diameter. Wash all of the pea gravel repeatedly before installation to remove all traces of sand, and screen particles larger than 3/8" from a portion of the gravel to be placed immediately adjacent to the slotted pipe.

Upflow gravel filters are used on the pressure side of a pump and are usually built at the bottom of the uppermost pond in a multi-pond system, or in a separate marsh or bog pond (see LILY POND and MARSH POND for examples). Like downflow gravel filters, a protection fabric is laid over the pond liner and a slotted pipe manifold is installed over the fabric. If the primary purpose of the upflow filter is to invisibly distribute water to form a header pool, the manifold is covered with a layer of pea gravel at least twice as thick as the pipe diameter. If the primary purpose of the upflow filter is to provide mechanical and biological filtration, the manifold is covered with a layer of 3/4" to 1-1/2" gravel at least twice as thick as the pipe diameter, and the large gravel is covered with 6" to 12" of pea gravel which is planted with water iris, cattails, and rushes, and other vegetation that thrives in saturated soil. In either case, wash all of the gravel repeatedly before installation to remove all traces of sand.

SLOTTED PIPE MANIFOLDS: Our slotted pipe manifolds assure uniform water distribution at the base of gravel filters. They consist of black PVC slotted pipe joined with flexible couplings, elbows, and tees that allow the manifold to conform to uneven pond bottoms. We can custom design a manifold for each project based on the pond size and shape, pump flow rate, and biological load, but as a "rule of thumb" our 2" slotted pipe can handle 200 gallons per hour per foot of pipe, our 3" slotted pipe can handle 300 gallons per hour per foot of pipe, and our 4" slotted pipe can handle 400 gallons per hour per foot of pipe. We will also supply flow control valves, drain valves, check valves, liner penetration fittings, and other accessory components required to make a complete system.

 

slotted pipe single

slotted pipe with end fittings

 

slotted pipe straight manifold
straignt manifold

 

 

slotted pipe F manifold
single-sided manifold

 

 

slotted pipe T manifold

double-sided manifold

 

PRICING: For pricing, see components listed in Hose and Pipe and Disconnect Devices.

 

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