Various Filtration Methods (Material Courtesy of Bob Hoffman, President, CWGS)

On The Waterfront

by Richard “Dick” Shuck
The 10% Solution©

Is your pond green and dirty?  Do you find yourself telling friends and  neighbors that ‘everybody’s pond looks like that’?  Would you appreciate a simple and quick way to clear it and clean it at the same time?  If the answer  to any of the above questions  is YES!, read on:  I’ve got the answer for you.

Clearing and cleaning a pond is not as difficult as many people believe.  In fact, the long, com­plicated formulas and equations you often read in garden and aquarium  magazines aren’t re­ally necessary.  All  you really need to know is the 10% solution.  Here’s how it works:

Construct a plants basin near your pond with an equivalent to 10% of the surface area of your pond.  Fill this basin with water plants and recirculate your pond’s water through it every two to four  hours.  Within a few short weeks your water will be clear, and your pond will be clean.  This is because your plants basin has si­multaneously consumed the “pea soup” caus­ing nutrients in your pond and removed the solid waste particles from your water via settling and root filtering.  Thus, your plants basin has be­ come a natural filter.

Depending upon the size of  your pond, this natural filter can be as small as a half whiskey barrel or as large as another small pond.  A pond that is 20 sq.ft. in size would require a 2 sq. ft. filter:  a pond 400 sq. ft. in size would require a 40 sq. ft. plants filter.  Larger filters can be constructed using 2 x 8 or 2 x 10 pressure treated lumber and a rubber or other flexible liner.  The filter should be 12″ to 18″ deep and equipped with an overflow so it can act as a settling cham­ber for solid waste removed from your pond.  The pond water should enter the filter at a point furthest from the overflow to maximize the dis­tance of water flow thereby allowing the great­est settlement of solids.  (A narrow shaped natu­ral filter is more effective than a round or oval shape.)

Almost any water plants will do well, but some of my favorites are:  Hardy Plants–yellow wa­ter iris, water mint, water celery, cattails, and lotus; Tropical  Plants–water hyacinth, water lettuce, giant or Egyptian papyrus, and umbrella palm.  Through trial and error, I’ve found all of these to work quite effectively in a natural fil­ter.  ln late fall, remove plants that have died and  strip leaves from hardy and perennial plants.  Clean your filter in late fall or early spring for the coming year.

Besides filtering out solids and clearing green water, your natural filter is an excellent biological filter as the plant roots pro­vide abundant surface area for nitri­fying bacteria.  When the plants are dormant (early spring and late fall), your pond water may “green up”.  Once the dormant spell is broken, however, rapid clearing will occur.  During dormant periods, it is extremely important to con­tinue using a mechanical foam filter to assure continued biological filtration.

One last thing:  The plants in your natural or plants filter will generally be healthier and many times larger than the plants in your pond.  This is because the plants in your filter get a constant flush of nutrients from the recirculat­ing pond water.  As you’re probably aware, this is the basis of hydroponic gardening.  And your plants filter will prove to be a testament to this progressive gardening system.

About the Writer:
Richard “Dick” Schuck is the owner and founder of Maryland Aquatic Nurseries, Ind. located at 3427 N. Furnace Road, Jarrettsville, MD.

They are growers of a wide variety of aquatic plants as well as designers and manufacturers of many water gardening products.  Chief among these products are pond filters, patio pool gardens, indoor water gardens, bird bath fountains, and new–habitat gardens for reptiles and am­phibians.

Surface Area of Natural Filter = 10% of Surface Area of Pond
Water Flow/hr. = 1/2 to 1/4 of Pond volume, Depth of Natural Filter = 10″ to 18″

Source:  PONDKEEPER, January/February 1996, Page 10

by Stan Ranson

Host ponds have been built as part of the general landscaping when it was considered a nice idea to have the sound of water in the background.  Later on, some goldfish were added to give the pond some life and some plants installed to try and clear up the water so it wasn’t so green.   When those beautiful Koi were discovered they just had to go in the pond but now . . . suddenly . . .  when there were brightly colored fish to look at they cou1d not be seen.  The green water became a major problem.  How can it be cured?

What you need is a filter.  But, you say, you already have one, it did well on a swimming pool, why  won’t it do the same thing on a  fish pond.  First of all, in a swimming pool you put lots of chlorine to help kill the green stuff  (algae, pronounced algee) and the water you put through the filter has very little in the way of solids in it.  Even so, you have to back-flush  that pool filter quite often otherwise the water will not go through it.  Just imagine unchlorinated water that has been used as a restaurant by a number of fish and a subsequent garbage can for un-eaten food and finally bathroom for those same fish.  Lots of crud, right.  That filter would soon get well and truly plugged and you would also need a high pow­ered  pump to push the water through.  That high power would show up on your electric bill as many dollars per month to run.  To operate a fish  pond and especially Koi, you need  to run the pump 24 hours a day and 365 days a year so you want the most economic pump you can get.

The type of filter needed for a fish pond is called a biological filter.  This will take the
wastes from the fish and process them naturally to produce a clean water return that will not endang­er the fish.  This is done through micro organisms that develop in the filter and they consume the ammonia produced by the fish and change it to nitrite and then nitrate.  Nitrate is needed by the fish and also by a very small growth of algae on the sides of the pond.  The fish eat this algae along with their other food and produce more ammonia which is processed again by the filter.

The biological filter can be built as either an ‘upflow’ or a ‘downflouw”.  The upflow is built outside the pond and the downflow inside the pond.  The trend is towards the upflow filter as it is a little easier to maintain and can be added easily to an existing pond.  The size is governed by the size of the pond.  Usually the filter is about 10% to 15% of the pond’s gallonage, although this depends on exposure to sun and depth of  pond.  For ponds up to 2,000 gallons, easily built barrel filters can be used.  Above 2,000  gallons you might want to consider a more permanent structure made out of concrete blocks.  Whether it is small or large the biological filter is always built the same way, you just need more materials if it is larger.

The philosophy of an upflow biological filter is:

a.  The water is pumped from the pond into the center pipe and air is induced by letting it fall on a dozen or so plastic hair curlers.

b.  The water reaches the bottom of the container and then percolates up through a support grid and three different grades of crushed rocks and sand.  The bacteria build their cells in the rocks and consume the ammonia laden debris as it passes by.

c.  The processed water at the top of the container is returned to the pond by a plastic pipe through the side.  This water can drop over a waterfall and thus induce oxygen into the pond which is a major requirement of the fish.

Maintenance of the filter is minimal but must be done periodically.

Daily . . . The heavier wastes from the pond are collected in an area at the bottom of the container under the grid.  If left in the container they would generate the breeding of an anaerobic bact­eria which would turn that debris into a foul smelling black goop.  A drain must be provided that can be opened daily and a few gallons of water let out.  This gets rid of the daily accumulation of material and also removes water from the pond.

Weekly . . . Clean out this area by attaching a hose to the water clean line in the container and open the bottom drain.  The water clean line should rotate so that water is jetted into the nooks and crannies in the bottom area.  The water removed from the pond during the week can be made up by spraying tap water into the pond.  Use a spray and this will reduce the chlorine in the water.  lf you have chloramines in your tap water then test for them prior to filling the pond.  If they are present you should use an ammonia reducer to eliminate most of them.

Major maintenance . . . About every 4 to 6 months the filter will start to clog up with dead cells from the friendly bacteria who have been doing all this work for us.  The water will not pass as readily through the media as before and so the flow will be reduced.  The air network is a network of 1/2 inch plastic pipe with a vertical pipe that is long enough to protrude above the water level in the container.  The net­work is glued together and consists of elbows, tees, and pipes that cover the grid area in the container.  Holes of 1/16 inch diameter about 2 inches apart are drilled in this network.  If air is induced into the vertical pipe it will come out of these small holes under all the media and send bubbles up to the top of the container.  These bubbles will bring with them a lot of the dead cells and other debris from within the gravel.  If the top of the container has a return line to the pond and also another outlet that is temporarily plugged, then the plug can be placed in the pond return and the dirty water from the cleaning chan­neled out of the second port.  Don’t over clean as you don’t want to lose all of the good bacteria that are making the filter work.  When the water in the top of the container is reasonably clean then open up the pond return and close up the other outlet and the filter is set for another 4 to 6 months.

For information on this or the downflow fil­ter please contact the author or the Ventura County Koi Society.

About dorothym

I am the Secretary of the Colorado Water Garden Society.
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1 Response to Various Filtration Methods (Material Courtesy of Bob Hoffman, President, CWGS)

  1. scallum says:

    Really good article. Thanks for taking the time to explain things in such great detail in a way that is easy to understand.

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