Sand Filter VS. Bead Filter For Ponds

ScatMan · Apr 19, 2011

does anyone use a regular pool sand filter for a fish pond?

will it work, if not, why not?

i've seen bead filters like the ultima ii, but what are the advantage over a traditional sand filter, if any?

it seems to me that a sand filter would trap smaller debris than a bead filter, is that true?

do sand filters plug up too quickly on a pond?

:help2:

please

mp3coupe · Apr 19, 2011

Sand filters in that style would probably clog pretty quick not to mention you probably need a bigger pump -pressure

ScatMan · Apr 19, 2011

that was one of my concerns, did you ever use one or know someone that did?

mp3coupe · Apr 19, 2011

ScatMan;5063272; said:
that was one of my concerns, did you ever use one or know someone that did?

I never used one but spent a great deal of time on several koi forums learning from other peoples mistakes. I read somewhere that people empty the sand and load it with k1 or other bio material and that works fairly well for bio, but not so much for trapping.

ScatMan · Apr 19, 2011

thanks. i just found a good article explaining why not to use a sand filter. i guess that solves the question.

Sand Filters Are A Bad Garden Pond Filter Choice

Why Is A Sand Filter Not A Suitable Biological Pond Filter?

The use of a sand filter in a garden pond as a biological pond filter is not a good idea, although there are those fish keepers who still use one as a means to remove solid matter.
Sand filters are used extensively in fish hatcheries, sewage treatment applications and in swimming pools (particularly in warmer climates like South Africa, Australia and the warmer southern states of the USA).
Sand filters from a cost point of view are expensive to run and havent been designed to remove the nitrogenous waste matter (ammonia) that needs to be removed from any garden pond or fish pond.
They have instead been designed to remove large particles of waste, although they do perform nitrification of ammonia, to a lesser extent.

The major purpose of a biological pond filter in any fish pond or water garden is to remove ammonia, which can be highly toxic to pond inhabitants in high concentrations.
The biological process responsible for removing ammonia is known as the Nitrogen Cycle and is critically important to any aquatic pond system.
The secondary function of a pond filter, which many novice pond keepers actually believe is the real purpose of a pond filter is to mechanically remove pond debris such as leaves and other organic matter such as flocculated algae (dead algae that has been destroyed by a UV sterilizer and has clumped together).
This article will hopefully help to convince you that using a sand filter in your garden pond actually has more disadvantages than advantages. I will also recommend suitable alternatives to using a sand filter for biological pond filtration purposes.
Why Are Sand Filters Bad For A Garden Pond?

Before I discuss my reasons why I believe that a sand filter has no place in a garden pond, I would quickly like to add that I am referring to a mechanical sand filter and not a fluidized sand filter, which has been designed for use as a biological filtration system for use in a pond environment.
As stated earlier in this article, sand filters are expensive to run on a continuous 24/7 basis. They also offer very little if any nitrification properties. The reasoning behind using a pond filter in the first place is to remove ammonia from your garden pond before it creates a toxic environment that is unsuitable for aquatic life, including pond fish, snails, frogs and toads etc to live in. Without the ability to perform the nitrification process (nitrogen cycle) which removes ammonia, it just does not make sense to me to use a sand filter as it doesnt perform this critically important function.

In a pond environment containing ammonia, it is the nitrifying bacteria, Nitrosomonas and Nitrobacter that are responsible for converting ammonia (toxic), firstly into nitrite (toxic) and then into nitrate (much less harmful). These microscopic beneficial bacteria live on the pond filter media, housed in the biological pond filter chamber. In order to ensure optimum ammonia conversion, certain criteria must be met: Firstly, oxygen needs to flow through the filter media as the conversion requires lots of oxygen; secondly a pond filter media with a high SSA (specific surface area) should be used to allow much larger colonies to form. The larger the biomass (size of colony) the quicker the ammonia will be broken down. Thirdly, turbulence which throws together water, oxygen and ammonia will significantly help to increase the rate at which ammonia can be broken down.

With this statement in mind please note that:

A sand filter has a low surface area on which nitrifying bacteria can colonize.

A sand filter encourages the build up of unwanted heterotrophic bacteria. Heterotrophic bacteria (needs carbon in its diet) unlike nitrifying bacteria (autotrophic bacteria that doesn't require carbon in its diet) is particularly bad in a pond environment as they produce hydrogen sulphide (rotten egg smell), ammonia and carbon dioxide. Let's think about that! We are using a sand filter to remove ammonia but in reality it produces ammonia! There is another disadvantage of encouraging heterotrophic bacteria growth and that is the fact that this unwanted bacteria colonizes much more rapidly than beneficial bacteria. As the heterotrophic bacteria colonies grow they pollute your pond water with pathogenic organisms that cause Koi and fish health problems.

A sand filter is costly to operate due to the number of backwashes required (5 to 6 per day for approximately 5 minutes each time). The flow rate needed to perform normal filtering is the same as that needed for backwashing. Many biological pond filter systems have 2 speeds; one speed for backwashing and a second one for filtering purposes. This saves on water usage and running costs.

A sand filter is only capable of trapping solids in water that measure at least 10 microns in diameter or more; algae cells can be as little as 4 microns, meaning that they would simply pass through the sand without being trapped. As algae cells increase in number they cause algae blooms (green pond water).

As water flows through the sand channelling starts to occur. This means that holes appear in the sand and water simply flows through, without being filtered.

As far as I am concerned the only viable solution for effective biological pond filtration in a garden pond containing fish is to use a biological pond filter or a veggie filter, although a veggie filter can be high maintenance.

What Type Of Biological Pond Filter Should I Use?

If you have a small to medium sized garden pond then the best choice would be a pressurized pond filter system. These units are far more compact than the traditional black box type pond filter and are much easier to hide from view. Due to the pressurized operation and the back flushing system they are also much easier to clean. Another advantage of pressurized bio filters is the fact that they can be situated away from the pond edge. Traditional box type filters need to be situated near to the pond, usually at the highest point, as they rely on gravity. Due to their size they are also more difficult to disguise and can be somewhat of an eyesore. Two of the best are Fishmate and Oase.

For large Koi ponds the best form of biological pond filtration is the fluidized bead biofilter (fluidized bed filter), more commonly known as a bead filter. Bead filters as the name suggests use tiny little beads as the filter media. In certain models there can be as many as 600,000 beads per cubic foot. This means that there is an extremely high SSA (specific surface area) on which beneficial nitrifying bacteria can colonize. These beads are suspended in a turbulent chamber of water that is constantly full of oxygen and ammonia.
The turbulent oxygen rich water, ammonia and large surface area provided by the beads ensure that ammonia is quickly converted in this type of pond filter.

Just to show the levels of oxygen needed for Nitrosomonas and Nitrobacter nitrifying bacteria to convert ammonia into nitrites and then into nitrates, take a look at the 2 equations below ...

For Nitrosomonas: 55NH4+ + 76O2 + 109HCO3- ---> C5H7O2N + 54NO2- + 57H2O + 104H2CO3

For Nitrobacter: 400NO2- + NH4+ + 4H2CO3 + HCO3- + 195O2 ---> C5H7O2N + 3H2O + 400NO3-

My advice to you would be to avoid installing a sand filter in your garden pond at all costs; partly due to running cost implications but mainly because of the unhealthy environment it will create. If you currently use a sand filter then remove it from your pond system ASAP. If you can't do this then replace the sand with a biological filter media such as Fishmate Supra Biomedia and find some method of introducing high quantities of oxygen into it.

Duncan6618 · Apr 19, 2011

I used a regular sand filter on my pool conversion which you can see here...http://www.monsterfishkeepers.com/forums/showthread.php?t=261937

The sand filter worked great as a mechanical filter but after some months the sand became gunked up, compacted, and requires daily backwashing. So that is the problem with sand filters. I'm replacing the sand with PermaBeads which are supposed to resolve those problems and still give excellent mechanical filtration.
http://cloggedsandfilter.com/pbmedia.html

They are quite expensive so that may negate the savings of a sand filter vs. bead filters.

On the pond bead filters the water flow up through the floating beads rather than down through the sand like on a sand filter. The bead filters are supposedly just modified sand filters and I have seen some threads on koi/pond forums where people just modify the plumbing on their sand filter to reverse the flow and turn it into a bead filter.

ScatMan · Apr 19, 2011

but now i found an article that's proclaiming sand filters to be the best option. :nilly:

now i don't know what's what.

http://www.koifishponds.com/state_of_the_art_filters.htm

By David A. Dec ©2002
Pond filtration requires two main components; both mechanical and biofiltration. First, the mechanical filtration needs to remove both the suspended particles and the debris that has settled to the bottom so the water is clear, and we can see our fish and plants. If not removed, this organic mulm can harbor dangerous organisms and chemicals that threaten the health of our pond.
Second, the biofiltration needs to change the toxic chemicals like ammonia and nitrites, to harmless or helpful chemicals like nitrates, oxygen, and nitrogen. This is done with biologically active bacteria species through the Nitrification process.
Effective Pond Volume

A recent buzzword in pond circles is Effective Pond Volume. People have found that selecting a filter based on how many gallons their pond holds is not at all accurate. Since biofiltration is dependent on the ammonia load from the ponds fish, biofilters needs to be sized according to the amount of fish wastes produced each day in the pond. This depends on the quantity of foods they consume each day.
Selecting a swimming pool filter is done by matching flow rates. However, the proper way to select a filter for a pond is to determine the maximum number of fish you are planning for the pond, and the weight of food you will feed them daily, plus the amount of algae and other natural pond food they eat. Typically the amount of food Koi eat is 1% to 3% of their weight.
How Much Food

Then you select the filter that will process that weight of food per day. However, this is not an easy task because many filter manufacturers feel compelled to match their competitors' exaggerated claims of their filters' capacities, which means the ability to process food to ammonia and nitrite levels of 0.0 to 0.1 parts per million (ppm). Unfortunately these manufacturers grossly overstate the amount of fish wastes that their filters will handle. We have done our own research into this and found most of their claims to be outlandish. Surprisingly if they were more accurate they would probably sell larger or multiple filter units to their customers, the result would be healthier fish, and everyone would be happier.
Don't forget the square area of the pond itself supplements the square area of the filter media, and can easily add 25% to 200% to the bacteria's total processing surface area.
Overfeeding the total square area for nitrification causes the ammonia and nitrite levels to increase to dangerously toxic levels, without frequent water changes. That is why many ponds are running ammonia and nitrite levels of 0.5 to 1 or more ppm, and their owners are wondering why their fish are sick and dieing.
Filters can also be combined in parallel or series depending on the application or the amount of food that needs to be processed.
Surface Area Efficiency

Our own research, as well as others, has shown that filters process about 0.1 gram of food per day per square foot of surface area in the filter media, at maximum nitrification efficiency. In other words, they convert the toxic ammonia to nitrites, and then the toxic nitrites to nitrates via the nitrification cycle. Since the bacteria live on the surface of the pond walls and filtration media, a larger surface area in the filter means there is more room for a larger bacteria colony to do the biofiltration.
The surface area in a filter is the filter medias surface area per cubic foot, times the number of cubic feet of media. A larger total surface area allows larger colonies of nitrifying bacteria to adhere to it.
The surface area in a filter is what makes it work. The larger the surface area the greater is its biological activity.
The most important consideration in purchasing a filter system is its surface area efficiency in dollars per square feet.
Sand

The surface area per cubic foot depends on the media. For instance, very fine sand with a diameter of 0.125 mm or .005 inches has 8,000 square feet of surface area per cubic foot. So a sand filter with 2 cubic feet of very fine sand has 16,000 square feet of surface area so it can process 1,600 grams or 3.5 pounds of food per day. Sand of this diameter in a filter results in a total cost about a nickel per square foot of surface area.
Sand with a diameter of 0.5 mm or .02 inches has 2,000 square feet of surface area per cubic foot; and results in a cost of about $0.20 per square foot of surface area.
Plastic Bead Filters

Plastic beads with a diameter of 5 mm or 0.2 inch have a surface area of 200 square feet per cubic feet or about 40 times less than sand. So a bead filter with the same 2 cubic feet of beads has only 400 square feet of surface area, so it can only process 40 grams or 1.5 ounces of food per day; much less than that for the sand filter.
For this reason when beads are used in filters the typical cost is $1.00 to $2.00 per square foot of surface area or 5x more than sand.
It is obvious that the media needs to have a very large surface area to host the nitrification bacteria. All the media up to this point have been solid, i.e. sand or plastic beads.
Hollow Media

A newer development is hollow media. If you took a miniature plastic hollow drinking straw, and formed internal walls inside it, you would not only have the external surface area, but also an internal surface area. They are 5 mm in diameter and vary in length from ¼ to ½.
This media has 750 square feet of surface area per cubic foot. So a filter with 2 cubic feet of media will have 1,500 square feet of surface area, and will be able to process 150 grams or 1/3 pound of food per day. This is over 4 times more efficient than bead filters, but 1/10th of the sand filters surface area.
Its cost when used in a filter is about $0.75 per square foot of surface area or more than 3x sand.
The first disadvantage of this new media is the difficulty of manufacturing it. The units are obviously very small and have a very complicated design, which makes them very expensive at about $200/ cu ft.
The second disadvantage is they are made of styrene. You can test this by putting some media in water. If it sinks it is most likely styrene. Another test is to burn it since styrene burns with a black sooty smoke. Styrene oxide as a contaminant of styrene is known to be very toxic to bacteria, which would be a disaster to bacterial colonies for nitrification.
Filter Operation

It is true that sand filters have been used in almost every swimming pool in the USA. They have been proven and constantly improved after millions of installations. They are obviously very effective, inexpensive, and are very easy to clean.
In fact, they are almost self-cleaning. You just turn a valve to backwash them. This saves lots of time, inconvenience, labor, mess, and wear and tear on the pond fish, and it automatically provides the small but frequent water changes needed to remove the dissolved chemicals.
During normal operation the water flows in through the top valve, travels down through the sand or filter media where the debris is trapped, and flows into 6 to 8 perforated plastic laterals connected to a hollow stem, and then out through the top valve back to the pool. During backwash the water is re-directed down the stem and through the plastic laterals, flowing up through the sand, carrying the debris out through the top valve to waste.
One way to select a swimming pool filter is by flow rates. For instance, if you are planning a flow rate of 110 GPM or 6,600 GPH you will want one 36" diameter filter, or possibly split the flow between two 24" filters, which would be cheaper.
Filtration flow rates in gallons per hour vary with the size of the filters as follows:

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Filter Diameter