A pressurized sand filter is an integral part of biological filtration. They act both as a mechanical and biological filter. Not only do sand filters trap 'stuff' on top of the sand, we colonize bacteria on the surface of the sand that eat the nutrients in the water that would otherwise build up and become toxic to the fish. See nitrification. We favor a pressurized sand filters and a 6 position back wash valves over a gravity filters because they are space efficient and are much easier to maintain and clean.

Sand filters are basically a canister with laterals, (slotted pipes) near the bottom and a diffuser near the top. Attached to the canister is a 6 position back wash valve that directs the movement of the water. The function of the back wash valve and the movement of the water are described in the back wash valve section. Often connected to the canister is an air bleeder valve, pressure gauge and bottom drain.

We have selected Sta Rite and Purex Triton TR sand filters because these filters are reliable, economical, easily back washed and are space savers compared to gravity filters. They are the same kind of filters that are used for swimming pools. Both have similar design with the exception that some of the Sta Rite filter split apart in the middle whereas the Purex Tritons do not. NOTE: We use clean course aquarium sand or the first 1/4 the volume in clean pea gravel and the balance in clean course aquarium sand.

Some people think that a sand filter is unnecessary and that a pond will function well 'naturally'. This may work for a while but eventually, in our opinion, this is short sighted thinking. Firstly, these ponds are not 'natural' and never will be. Secondly, watch a natural pond over time and see if that is what you want to happen to your pond. They fill up and become a bog and eventually a meadow. A pond, like a house or other landscaping, needs regular maintenance to keep them up. Some people can live in a house without taking out the trash for weeks or longer. I can't. Not being able to get rid of excess nutrients in the pond water is the dangerous for the fish and leads to a very unsitely pond. See pond overview.

Our idea is to have the best equipment available to maintain a healthy, esthetically pleasing pond with a reasonable amount of maintenance. Also, we think it is easier, and better for the pond, to maintain a pond a little at a time and not try to dig out, literally, a pond that has been ignored for years. An important part or having a healthy pond is to have the right size sand filter.

The effectiveness of the filter is largely a factor of how fast the water passes through the sand. The slower the water moves, the more material can be filtered out. If you have a big pump and small filter, the water will move so fast, you could pass golf balls through it, almost. Having the correct size filter is probably your biggest ally to maintaining a healthy pond.

The size of the filter is determined by the number of gallons in the pond and the number of fish and plants anticipated.Once you have determined how many gallons there will be in the pond, select a filter that can handle that many gallons every two hours. For example, if you have a 8,000 gallon pond, you will need a filter that can handle 4,000 gallons/hour or about 67 gallons/minute. If you are on the border between sizes you are better off going with the bigger size to keep the flow rate rate down.

Each filter comes with directions from the manufacturer. We encourage you to lay out all the equipment; pump and leaf trap, sand filter and back wash valve, UV light and Jandy 3 way valve (if needed) before start cutting and gluing. See pump/filter schemata and PVC pipe gluing and Zen and the Art of Plumbing.

The sand filter need to be set on a firm base of crushed gravel, concrete cap blocks (1-1/2"x8"x12") or a concrete pad. If the native soil is susceptible to settling when wet, the dirt should be removed and replaced with compacted rock such as crushed shale. Some of the bigger filters will weigh over 1400 pounds when in operation.

Mount the Back wash valve (BWV) on the side of the filter. (Hand tighten only.) Lay out the pump, filter and ultraviolet light. Different back wash valve have different configurations. Keep in mind where the pipes will go. You want to keep the pipe from the pump to the filter as simple as possible. We can usually do it with only two 45° fittings. Remember, we want to keep the piping as simple as possible using only as many 45° elbows as necessary and as few 90° elbows as possible. many pumps come with unions. If your pump doesn't, be sure to put a union bZetween the pump and filter. See PVC cutting and gluing for more hints.

Yet again, depending upon the backwash valve, it may have a female threaded fitting or a slip fitting. With a threaded fitting, you can use a male fitting, a male threaded 90° elbow, a threaded male union or cut an end of a PVC nipple to thread in the opening. Remember, think in 45°s, not 90°s when possible. See Zen and the Art of Plumbing. Connect the BWV to the return pipe with a union. The return pipe then may go to a Jandy 3 way valve if there is one pipe directly to the pond and another pipe to the waterfall. The waterfall is usually higher that the filter and it is necessary to put a check valve in the pipe so we do not drain the pipe every time we open the leaf trap by the pump. If you are using a Jandy three way valve, install the check valve after the Jandy. See Pump/Filter schemata.

Again, we want to use as many 45°s as necessary and the fewest 90°s. If there is a lot of spaghetti in the piping a lot of action during back washing would be lost.

It is good insurance to put a ball valve in the waste pipe to insure that no water is lost. If you are using a 1-1/2" BWV and the run is greater than 15', think about upgrading to a two inch pipe.

These generalized instructions are written for the filters that have a hole in the top of the filter. The same instructions apply for filters with a split housing.

Check to see that laterals are hand tight. Do not over tighten. If the lateral are slotted on only one side, the slots should face downward for maximum filtration.

If the diffuser in the hole of the filter has a little air relief tube with a screen on it, remove it and don't step on it. Move the diffuser aside. We wash all the gravel and sand with a kitchen sieve in a bucket of water to remove the small sand that can, and will get stuck into the laterals requiring removal of sand. An ounce of prevention is worth avoiding a dirty job. Be sure not to get sand in the diffuser.

For a 'hole-in-the-top-filter, put the 'O' ring on the male threads of the dome and lubricate with silicon lube. Make sure threads on filter are clean and lubed. Screw down dome using wrench provided.

For a split-body filter, put the gasket around the lower filter housing. Place upper housing in place. Install compression band or fittings. No lube is required.

After a few years, most sand filters require cleaning. If you are experiencing volume loss that is not improved very long by back washing, the problem may be there is a lot of gunk and caked algae collected on top or in the top layer of the sand. Double check to see is the volume is restored with the BWV on 'recirculate'. If it does, its time to clean the filter. Wear long sleeves so you don't get fiberglass from the filter opening on your upper arm. See Trouble Shooting for more help to determine volume loss.

If you have the proper size sand, there is no point in getting new sand. We just need to get the sand out of the filter, clean it and replace it. Once it is out, it is easy to clean and expensive to replace. How difficult or easy the job is depends upon the type of filter you have. For all filters, make sure power is off and open air bleeder valve or otherwise depressurize filter. Move Back wash valve to closed. Bring out a radio and put on some good tunes.

For those of you with a split-housing filter it is relatively easy to loosen the compression band and remove the upper housing. Then scoop out the sand using a plastic container. Skip to Lateral Removal.

For a hole-in-the-top-filter, there are two or maybe three ways to remove the sand. The sand can be removed through the hole by scooping of siphoning if your have a sand siphon. With the newer Triton filters by Pac Fab you can remove the housing for the drain plug but this is very messy especially if you want to reuse the sand.

Scooping Wear long sleeves. Remove the dome and the little screen and move the diffuser aside. Don't get sand in it. If there is a bottom drain, you may be able to drain out the water. Often they are clogged. You can either scoop out the water or siphon it out with a tube or garden hose. Use a plastic glass, yogurt container etc. scoop out the sand.

Siphoning Wear long sleeves. Now we use a sand vacuum which hooks up to a garden hose and siphons out most of the sand. The lower you put your buckets, the more sand you can get out. If you have someone to help move the siphon for bucket to bucket so that you don't have to turn off the water to move it, you can siphon out almost all of the sand. Put the sand in buckets or a wheelbarrow.

Draining The newer Pac Fab Triton filters have a 2" sand drain located at the base of the canister. The drain plug is located in the sand drain. You can remove the drain plug and then the sand drain. I recall that the threads are reverse so you turn it to the right. If the sand is really caked it may be necessary to get into the filter with your hand or garden hose to loosen the sand.

As you remove the sand, you will encounter 8 or 16 laterals about 6 inches above the bottom of the filter. Remove them carefully by turning them counterclockwise. If you have a TR140 or short arms, it may be helpful to rotate the lower pipe assembly to which the laterals are attached. Clean the lateral with a brush such as an old toothbrush.

(Ground Fault Interrupter) is a safety feature that is found in most kitchens and bathrooms or anywhere near water. A circuit breaker trips when the temperature gets too high and takes a few seconds to trip. A GFI, on the other hand, trips when there is a slight loss of current and trip much faster than a circuit breaker. Some circuit breakers are GFI as well but have a reputation as sometimes being unreliable. All pumps and lights should be GFI protected.

All pumps and 120v lights need to be properly grounded. For pump, we usually drive an eight foot copper-coated steel rod into the ground and attach it to the grounding terminal on the outside of the pump. This connection is made with a grounding clamp and #6 bare copper wire. Follow all local codes.

All lights need to be grounded. Light canisters for gunite (concrete) all have grounding lugs on the outside. The lugs are connected to the rebar with bare # 6 copper wire. In addition, the lights themselves have grounding wires that need to be connected to a GFI.

is a unit for measuring the power of motors, engines and pumps. It is equivalent to 746 watts. That is to say, running an one horse power pump takes about the same electricity as turning on seven 100 watt and one 50 watt light bulbs. Therefore, using the Sta-Rite JW two speed 1/8-3/4 horse power pump take about the same juice on low as a 95 watt light.

Not all horsepowers are equal. All pump now come with something called 'service factor'. Officially, the service factor indicates the degree to which as electric motor can be operated over a specified horsepower without danger of overload. Unofficially, its a fudge factor to make a 1 hp pump can look like a 1.5 hp pump. A 1 hp pump with a service factor of 1.65 is exactly the same pump with the same output as a 1.5 hp pump with aservice factor of 1.1. The only thing differant is the number on the name plate. Because of the confusion, many companies are forced to carry both of the pumps in different packaging.

Beware of the fast sales person that says they can sell you a 1.5 hp pump for the same cost as a 1 hp one. Check the service factor and if he/she/it is trying to get a fast one past you, return to the reputable dealer.

is the study of the movement of water and its applications. We will write more about this as time allows. Hydrology is the theoretical basis by which we select pumps, filter, design and about everything else concerning a pond or filter. Examples: As discussed in Pipe Size, we are limited by the laws of hydrology as to how much water we can pass through a pipe. Also, if we are going to use two bottom drains in a pond, we have ways of plumbing them to get a balanced flow between the two naturally.

as described in Trouble shooting, if the water volume does not improve with the back wash vale on recirculate, it may be that the impeller is clogged. Cleaning the impeller is more often necessary if the pond is under pine trees because the needles can get through the leaf baskets.

open up the electrical cover and place a wrench (often 3/8")on the shaft and loosen the impeller by hand. They usually are counterclockwise (normal) thread and you have to crank on it.