Contact Form
Name *
Email *
Telephone
Subject *
Message *
Attachment
Enter Security Code *
1Xi7LfV
Contact Us

Filter Selection

Introduction

Maintaining a healthy pond environment with crystal clear water usually requires a filtration system. Filtration systems perform one or several of the following functions:

1) Mechanical Filtration - these trap particles in a material of some type for later removal during cleaning

2) Biological Filtration - these use beneficial bacteria to feed on impurities in the water; the bacteria break down fish wastes and other organic matter

3) Ultra-Violet Clarification - by exposing water to ultra-violet light, single-cell algae (waterborne algae) clump together for easier removal by a mechanical filter

Most filters for mid-size and large ponds employ a combination of mechanical filtration and biological filtration, and many can accommodate an ultra-violet clarifier as an option.

Depending on brand and model, the mechanical filtration can consist of layers of foam pads, trays of gravel, foam cartridges, or brushes. Some models combine several of these into one filter. In addition, many filters contain a chamber for plastic bio-media. These are specially designed plastic pieces 1 to 2 inches in diameter. One cubic foot of these pieces can contain as much as 84 square feet of surface area. This large surface area encourages the growth of beneficial bacteria colonies - the secret of effective biofiltration. Once the colony is established, it converts ammonia from fish waste, dead organic matter and other impurities into nitrites and later into harmless nitrates and nitrogen which help promote the growth of plants.

Without help, it can take up to seven weeks for a bacteria colony to take up residence and grow large enough to be effective in a typical biofilter. This process can be accelerated through the introduction of additional bacteria, available either in dry, granular or liquid form.

The rate of water flow through the biofilter will have a major effect on its effectiveness. All filters have a maximum flow rate. This flow rate must be observed. Slower flow rates may result in the volume of the pond not passing through the filter as often as it should for efficient filtration to occur. Faster water flow will not allow the bacteria enough time to clean the water completely and may even dislodge the bacteria from the media. Likewise, care should be taken when cleaning a biofilter. Mechanical elements (filter foam) should be rinsed in a separate container of pond water. If the filter contains more than one layer of filter foam, clean them in rotation. The biomedia should not be disturbed to enable the beneficial bacteria to remain.


Types of Filters

There are a number of different filter designs.

a) In-Pond Filters
These small filters usually fit on the intake of the pump or around the pump itself and allow you to run a fountain head or waterfall off the pump's discharge. They are usually only used in smaller ponds and tend to me more difficult to maintain because they have to be removed from the pond for cleaning. An in-pond filter is not to be confused with a pump pre-filter. Pump pre-filters are usually small foam filters designed to protect the pump from large particles that may cause it to clog up. Pump pre-filters are not designed to filter the pond water.

b) Above-Ground Filters
There are two main types of above-ground filters. Pressurized and gravity-discharge.  
Above ground filters are easier to perform routine maintenance on because they are already out of the pond. Pressurized filters (such as ProEco Products CPF Series) allow you to filter the water and discharge it under pressure to the top of a waterfall. The amount of lift that can be achieved after the filter discharge is limited and should be restricted to a couple of feet. This type of filter is fairly easy to camouflage. It can be hidden behind a shrub or, in the case of the ProEco Products CPF models, they can be buried in the surrounding area up to the level of the lid. Gravity-discharge filters (such as most other styles of above-ground filters) must be placed so that the water discharges freely by gravity only. To operate a waterfall or stream with a gravity-discharge filter, it must be situated at the highest elevation, with the discharge pipe feeding the waterfall/stream by gravity. These filters are for above ground use only and are usually set at the edge of the pond.

All models are available in a wide range of sizes to accommodate most sizes of ponds.


Filter Selection

Please calculate the actual pond volume and use this figure to calculate the effective volume of your pond. Add in an allowance for fish stocking levels if necessary.

All filters have a maximum pond volume that they are rated for. You have to choose a filter that is rated for the effective volume of your pond (with an allowance for fish stocking levels if applicable).


Small & Shallow Ponds (up to 250 gallons approx.)

Due to the special requirements and unique circumstances found in small and shallow ponds, including most pre-formed units, we recommend to use a pond filter that is rated for double the effective pond volume.

Example
If the effective volume of your pond is 150 gallons, look for a filter that is rated for ponds up to 300 gallons.


Plain Water Filtration - No Waterfall or Stream

This is filtration at its simplest. All you require is a pond filter/pump combination that is rated for the effective volume (plus an allowance for fish stocking level, if applicable) of your pond.

You would start by selecting a pond filter that has a maximum pond volume rating greater than the effective volume of your pond. Go to our main pond filters page and have a look at our selection. Pick any filter that is sized correctly and suits your particular setup, in-pond or above-ground.

If an in-pond filter is the most suitable, all you have to do is place it in the pond and plug it in. Most of these filters have a pump included with them and many come with small fountain heads. If you add a short piece of tubing, many can be used to operate a small waterfall or spitter.

If an above-ground filter is the most suitable, the type you choose will depend upon the effective volume of the pond as well as the type of installation that you have planned. Above-ground filters do not include a pump which must be purchased separately.

Hint

When you are sizing the pump, remember to place the pump as far away from the filter discharge as possible. This will maximize water circulation within the pond.

Each filter has a maximum flow rate listed for it. This is the maximum amount of water that the pump can supply to the filter. If you exceed this amount, the filter will not work as efficiently, it might overflow and you may damage the filter unit. You will have to calculate the total head to the filter intake. Once you have calculated the total head to the intake of the filter, go to our main pumps page and select an appropriate pump based on the required flow rate at the total head at the filter intake. Pick a pump that will deliver close to but does not exceed the flow rate that the filter requires. The final selection is up to you. Criteria would be initial cost, power consumption, and  manufacturer's warranty. The yearly operating cost comparison figures on the website make it easy to determine which pump will be most ecomomical to operate over the long term. Sometimes, a less expensive pump with a high power consumption will end up costing you more in the end.

Hint
For filtration purposes, rather than using a pump with an integrated foam pre-filter, we recommend to use a pump that comes with a screen housing. The foam pre-filters clog up quite easily and require a lot of maintenance. On some pumps, like the Pondmaster Mag Drive, 250 GPH and larger models, the foam pre-filter can be replaced with a mesh filter screen.

The tubing size running from the pump to the pond filter is determined by the maximum flow rate of the pump you select, as well as the intake fitting size of the pond filter. Most pond filters feature step-down hose tails which allow attaching several different tubing diameters, for example from 3/4" to 1-1/2". Filter intake fitting sizes are shown for each filter. Recommended tubing sizes are listed for each pump that we sell. Pick the tubing diameter that is most appropriate for the filter and the pump. If you can not find a listing for your pump, you can also use the tubing flow rate chart to determine the correct tubing (please remember to ensure that it will fit on the filter intake). A hose adapter or a combination of adapters may be required to attach the tubing between the pump and the filter.


Waterfalls & Streams

Introduction

Choosing a filter to use in combination with a waterfall or stream can be a little more complicated but, again, all you require is a pond filter/pump combination that is rated for the effective volume (plus an allowance for fish stocking levels, if applicable) of your pond.

Select the pond filter that is rated for the effective pond volume that you have. Go to our main pond filters page and have a look at our selection. Pick any filter that suits your particular setup, in-pond or above-ground.

You will also need to determine the flow requirements for your waterfall. The volume required will be based upon the effect that you wish to see and the width of the waterfall that you have constructed. Please go to the How to Select a Pump/Waterfalls & Streams section to calculate your flow requirements. You will need this figure later on in the calculations.


Using an In-Pond Filter

Please take a moment to review the introduction above where sizing requirements and filter selection are covered. All of the information contained hereafter is based upon this.

If you have a small pond and waterfall and the in-pond filters are the most suitable, all you really have to be concerned with is the expected flow rate down the waterfall. Since most of these filters have a pump included with them, have a look at the flow rates for the pump that the filter is supplied with. Does the pump/filter flow rate correspond to the volume requirements that you calculated ? If you have more flow than you require, many of these filters also come with small fountain heads. If the waterfall will be very small, it may be possible to have both a fountain display and a small waterfall. If the flow is just adequate, you will likely have to replace the fountain heads with a short piece of tubing and operate only the waterfall. If the amount of flow is not adequate, you may want to get a separate pump to supplement the flow of water down the waterfall.

An above ground filter is usually the most suitable due to maintenance concerns, design of the pond and/or the effective volume of the pond. Above ground filters do not come with a pump. Sizing the pump will depend upon whether you wish to operate the filter and waterfall with only one pump or if you will use separate pumps for the two items. If you are using separate pumps, you simply size a pump for each application. If you want to operate both items from one pump, this becomes much trickier.


Using an Above-Ground Filter

There are two basic types of above-ground filters, pressurized and gravity discharge. If you choose a pressurized filter, you will have different things to consider than with a gravity discharge filter.


Above-Ground Pressurized Filters

Please take a moment to review the introduction to this section where sizing requirements and filter selection are covered. All of the information contained hereafter is based upon this.

Even though the water coming out of the discharge of the pressurized filter is under pressure, the amount of vertical lift and the length of horizontal hose run after the filter discharge should be kept as small as possible. Even two feet of vertical lift and/or 10' of tubing run after the filter discharge can decrease the flow rate a great deal. The best indication of what you can expect is in the performance rating for the pump that you have chosen to operate the pressurized filter.

Example
TheNursery Pro NPU1000 pump has a maximum flow rate of 1,000 GPH at a 1' head.  If you have 3' vertical lift to the top of the waterfall and 20' of total tubing run in the entire system, you would have a total head of  5'. If you operated the pump alone you could not expect more than 800 GPH. The same NPU1000 pump in combination with a Bioforce 2000 filter (maximum flow rate 1,000 GPH) installed at ground level and adjacent to the pond with 10' of hose between the pump and the filter intake, another 10' of hose attached to the filter discharge and a 3' vertical lift to the top of the waterfall after the filter discharge, would result in an estimated flow rate of approx. 650 to 700 GPH. The lower flow rate is due to friction losses caused by the filtration process. As the filter becomes clogged the flow rate would continue to drop.

To avoid this, place the pressurized filter so that the majority of the hose run and the vertical lift is before the filter intake. This will enable you to use a slightly larger pump to provide as close to but not over the maximum flow rate for the filter. Using this system and the example above, and assuming that you were able to install the Bioforce 2000 filter at the top of the waterfall, you could use a pump that would supply the filter intake with up to 1,000 GPH at a head of 5' and achieve a flow rate of approx. 900 GPH out of the filter (this will of course depend upon the pump that
you choose).

Whichever setup you plan to use, calculate the total head at the intake of the filter and be sure to note the maximum flow rate for the filter you have chosen. Then go to our main pumps page and select an appropriate pump that will deliver close to but not over the flow rate that the filter you have chosen will require at whatever the total head is. The final selection is up to you. Criteria would be initial cost, power consumption, and manufacturer's warranty. The yearly operating cost comparison figures on the website make it easy to determine which pump will be most ecomomical to operate over the long term. Sometimes, a less expensive pump with a high power consumption will end up costing you more in the end.

Hint
For filtration purposes, rather than using a pump with an integrated foam pre-filter, we recommend to use a pump that comes with a screen housing. The foam pre-filters clog up quite easily and require a lot of maintenance. On some pumps, like the Pondmaster Mag Drive, 250 GPH and larger models, the foam pre-filter can be replaced with a mesh filter screen.

The last consideration would be the flow rate that you will be getting out of the end of the discharge hose coming from the filter/pump. Does this correspond to the flow rate requirements for your waterfall that you calculated previously ? If the volume coming out of the filter is not sufficient, you can either use a filter sized for a larger pond volume, get a separate pump to operate and/or supplement the flow of water coming down the waterfall, or use a larger pump and split the volume of water between the filter and the waterfall. Please click here for more details on how to do
this.

The tubing size running from the pump to the pond filter is determined by the maximum flow rate of the pump you select, as well as the intake fitting size of the pond filter. Most pond filters feature step-down hose tails which allow attaching several different tubing diameters, for example from 3/4" to 1-1/2". Filter intake fitting sizes are shown for each filter. Recommended tubing sizes are listed for each pump that we sell. Pick the tubing diameter that is most appropriate for the filter and the pump. If you can not find a listing for your pump, you can also use the tubing flow rate chart to determine the correct tubing (please remember to ensure that it will fit on the filter intake). A hose adapter or a combination of adapters may be required to attach the tubing betwwen the pump and the filter.


Above-Ground Gravity Discharge Filters

Please take a moment to review the introduction to this section where sizing requirements and filter selection are covered. All of the information contained hereafter is based upon this.

Using a gravity discharge filter for this type of installation will have a few limitations. Since they are gravity discharge, they have to be situated at the top of the stream or within the waterfall so that the water can flow freely from the filter discharge. If you are able to overcome this, your waterfall will be limited to the amount of water that is flowing through the filter.

These filters do not include a pump. Now you have to find a pump that is suitable. As mentioned earlier, place the pump as far away from the waterfall as possible. This will maximize water circulation within the pond. Calculate the total head to the position where the filter intake will be located. Each type and size of filter has a maximum flow rate listed for it. This is the flow rate that you have to supply the filter with at the total head that you just calculated.

Now go to our main pumps page and select an appropriate pump that will deliver close to but not over the flow rate that the filter you have chosen will require at your total head. The final selection is up to you. Criteria would be initial cost, power consumption, and manufacturer's warranty. The yearly operating cost comparison figures on the website make it easy to determine which pump will be most ecomomical to operate over the long term. Sometimes, a less expensive pump with a high power consumption will end up costing you more in the end.

Hint
For filtration purposes, rather than using a pump with an integrated foam pre-filter, we recommend to use a pump that comes with a screen housing. The foam pre-filters clog up quite easily and require a lot of maintenance. On some pumps, like the Pondmaster Mag Drive, 250 GPH and larger models, the foam pre-filter can be replaced with a mesh filter screen.

The tubing size running from the pump to the pond filter is determined by the maximum flow rate of the pump you select, as well as the intake fitting size of the pond filter. Most pond filters feature step-down hose tails which allow attaching several different tubing diameters, for example from 3/4" to 1-1/2". Filter intake fitting sizes are shown for each filter. Recommended tubing sizes are listed for each pump that we sell. Pick the tubing diameter that is most appropriate for the filter and the pump. If you can not find a listing for your pump, you can also use the tubing flow rate chart to determine the correct tubing (please remember to ensure that it will fit on the filter intake). A hose adapter or a combination of adapters may be required to attach the tubing between the pump and the filter.

The amount of water that you put into the filter will be the flow rate that is available for your waterfall.  You will,  however, lose a little volume to the filtration process and the volume will decrease as the filter becomes clogged. Does the flow rate that you will be getting out of the filter correspond to the flow rate requirements for your waterfall that you calculated previously ?

At the beginning of this section we said that things can get a little more complicated when combining a pond filter with a waterfall. Why ? Because the amount of water coming out the discharge of the filter may not correspond with the amount of water you would like to see coming over your waterfall. It is possible that you will require more water coming down the waterfall than the filter is capable of supplying. If this is the case, all you can do is install a second pump to supplement the flow or use a pump that provides a larger flow rate than what is required for the filter. You will have to split the water coming from the pump discharge into two. One of the hoses would simply empty at the top of the waterfall. The water in the other hose would go through the filter and then make its way down the waterfall. You will likely have to install ball valves or some method of regulating the flow into one of the two lines to ensure that the maximum flow rate for the filter is not exceeded.

Please choose further options for your pond needs on the left side of this page.

proeco products
aquascape
atlantic water gardens
crystal clear
firestone
hikari
microbe-lift
oase
pondmaster