PRESSURE FILTERS

Pressure filters are sealed plastic tanks containing a filter media that provides mechanical filtration and supports bacterial colonies that provide biological filtration. They are built using the same tanks and control valves used for swimming pool filters, but have been completely re-engineered internally. Originally developed for the commercial aquaculture industry, this type of filter is ideal for koi ponds or any ponds with a significant fish population. We offer two versions with proven reliability. One uses a hollow plastic media that is very resistant to clogging but requires considerable water for backwashing; the other uses solid plastic media that clogs easier but includes an air blower that provides very effective backwashing with a minimum of water.

DESIGNING FOR PRESSURE FILTERS: Since pressure filters do not rely on gravity flow on either the inlet or outlet side, they have few design limitations. When used with submersible pumps, water can be pumped over the pond edge or through the side of the pond to the filter. The filter can be located either above or below the water surface and can be a considerable distance away. With external pumps, water can be drawn over the pond edge, through the side of the pond, or through the bottom of the pond. When water is drawn over the pond edge, the pump must be located above the water surface and the suction line cannot dip before reaching the pump inlet. When water is drawn through the side of the pond or through the bottom of the pond the filter can be located either above or below the water surface and dips in the line are only a problem when they occur above the water surface. The distance between the pond and the pump should be kept as small as possible, but long suction lines are possible with proper pipe sizing.

When filled with water, pressure filters are very heavy and require a strong, level base. When pressure filters are installed in pits, outbuildings, and other confined spaces, the clear ceiling height of the space must be at least twice the height of the tank so the control valve and internal plumbing can be removed. We provide unions for each of the pipe connections to facilitate disassembly of the tank for annual cleaning. During the backwash and rinse cycles, waste will flow through the backwash port which needs to be plumbed to an ornamental plant garden or other suitable site.

Effective prefiltration will significantly reduce maintenance requirements for pressure filters. The ideal technique for heavy solids loads is to use an external pump to draw from a vortex prefilter that is gravity fed from a bottom drain (see A KOI POND), but this is the most difficult to install. More typically, the external pump draws through a slotted pipe intake assembly.

HOLLOW MEDIA PRESSURE FILTERS: Hollow media pressure filters contain millions of small ribbed plastic tubes that float in the upper half of the tank. Water enters and exits the filter through a sophisticated yet easy-to-use multi-port valve with filter, backwash, and rinse settings. With the valve set to filter, the water flows out of slots at the bottom of the tank, passes through the floating plastic media where it is mechanically strained and biologically filtered, and flows out through slots at the top. During backwash, internal jets generate a cyclonic action that blasts the media apart, then lifts and spins it, separating the waste and flushing it away.

hollow media pressure filter

hollow-media
pressure filter

pressure filter with submersible pump

pressure filter with intake
manifold and submersible pump

We offer eight hollow-media pressure filters for ponds up to 60,000 gallons; for larger ponds, several filters can be ganged together. The following chart shows specifications for each:

Characteristics of Hollow-Media Pressure Filters
pond	fish	flow	ports	pump	waste	media	size
1000 gal	100 lbs	1000 gph	1.5"	EP12	50 gal	5 lbs	15"x27"
2000 gal	200 lbs	2000 gph	1.5"	EP12	100 gal	10 lbs	17"x36"
4000 gal	400 lbs	4000 gph	1.5", 2"	EP25	150 gal	24 lbs	21"x41"
6000 gal	650 lbs	6000 gph	2"	EP33	200 gal	36 lbs	22"x44"
10000 gal	1300 lbs	7500 gph	2"	EP50	300 gal	48 lbs	25"x46"
20000 gal	2000 lbs	7500 gph	2"	EP75	450 gal	84 lbs	31"x50"
30000 gal	3000 lbs	7500 gph	2"	EP100	600 gal	120 lbs	40"x49"
30000 gal	3000 lbs	15000 gph	3"	EP150	600 gal	60 lbs	40"x49"
60000 gal	6000 lbs	15000 gph	3"	EP150	750 gal	100 lbs	54"x46"

Routine maintenance takes about fifteen minutes each week. First, the pump is turned off and the control valve is rotated to the backwash position. Next, the pump is run for thirty to sixty seconds to carry the accumulated organic matter flows through the waste outlet for disposal. When the sight glass is clear, the pump is turned off, the control valve is rotated to the rinse position, and the pump is run again for a few seconds until the sight glass is again clear. This backwash/rinse sequence is repeated three times. Finally, the valve is returned to the filter position and normal operation resumes.

SOLID MEDIA PRESSURE FILTERS: Solid media pressure filters, often called bead filters, contain millions of 1/8" diameter solid plastic spheres that float in the upper half of the tank. Water enters and exits the filter through a sophisticated yet easy-to-use multi-port valve with filter, backwash, and rinse settings. In the Aquadyne bead filter we offer, the water then passes through the patented low-friction central diffuser column that virtually eliminates the frequent clogging associated with other bead systems on the market. With the valve set to filter, the water flows out of slots at the bottom of the diffuser column, passes through the floating plastic media where it is mechanically strained and biologically filtered, and flows out through slots at the top of the diffuser.

bead filter with external pump

solid-media pressure filter with pump and backwash blower

Routine maintenance takes about fifteen minutes, once each week. First, the pump is turned off, the control valve is rotated to the rinse position, and the air blower is operated for a few minutes to break up the beads and dislodge organic matter. Next, the control valve is rotated to the backwash position and the pump is turned on to carry accumulated organic matter through the waste line for disposal. When the sight glass is clear, the pump is turned off, the control valve is rotated to the rinse position, and the pump is turned on again. After the sight glass is again clear, the valve is returned to the filter position and the sludge valve is opened for a few seconds to purge sludge that accumlates at the bottom of the tank.

We offer four solid-media pressure filters for ponds up to 28,000 gallons; for larger ponds, several filters can be ganged together. The following chart shows specifications for each filter. All are supplied with air blowers to permit backwashing with low-pressure energy-efficient pumps: note the dramatically lower waste water volume when compared with hollow media filters without air blowers.

Characteristics of Solid-Media Pressure Filters
pond	fish	flow	ports	pump	waste	media	size
3500 gal	65 lbs	3000 gal	1.5"	EP12	30 gal	40 lbs	18"x38"
7500 gal	150 lbs	4000 gal	1.5", 2"	EP25	50 gal	80 lbs	24"x46"
14000 gal	300 lbs	6000 gal	2"	EP33	60 gal	160 lbs	30"x46"
28000 gal	480 lbs	6000 gal	2"	EP33	80 gal	320 lbs	36"x48"

PRICING: Call or email for current pricing.

return to top of page