Controlling GREEN WATER is the BOG’s Job:

Consider a location next to your pond for a Bog area. This will proved filtration for your pond. The area should be about 1/3 the size of your pond and located uphill from your pond.

The bog filtration area can be part of a water fall or stream. Construction of the bog area can be done at a later time. Do not throw away any pieces of pond liner. Bog filtration areas provide growing areas for some of the prettiest flowers found around a pond.

It is not necessary to have a hill or berm for a waterfall to get the benefit of a bog filtration area. You will need an space just higher than the surface of your pond.

A filtration bog is just a shallow pond 6 to 9 inches deep filled with pea gravel and some larger rocks. Water is pumped in to the bog at one side and trickles out of the other side. Bog plants(ones that like soggy soil) are planted in the pea gravel of the bog. Water flow through the bog is a gentle flow. The current hardly bends a leaf or moves a pebble. The slow moving water gives the plants ample time to pick up the nutrients (converted fish poop) and covert it into plant material.

CONSTRUCTION OF THE BOG: Dish out a spot in the berm or raised area , beside your pond. Lay some of that left over liner into this depression. The overflow of your bog should be the lowest side of your bog leading back to your pond. The other 3 sides should be at LEAST 4 inches higher than this overflow lip.

We will be seaming liner where the bog liner laps OVER the pond liner. This is done with 50 year silicone caulk or polystyrene spay foam "Greatstuff (tm)" between the two liners just over the edge of the pond( on the side of the "keeper ledge") Add rock back onto the liner this will help with the bonding. Fill the bog with pea gravel up to the point it is just below or level with the overflow. Stack in rocks around the edge of the bog to cover the liner. The pipe can be hidden in the rocks.

A small water fall is built on the overflow by spraying a small line of "Greatstuff (tm)" foam and placing a flat rock onto the foam. The foam can be sprayed on the liner and on the rocks to form a seal. Your entire water fall can be built using the foam instead of using concrete cement. (1 foot of water fall elevation per day) NOTE: once again the finished liner edge should point UP! The overflow spot going back into the pond, the liner points DOWN!

The pump should move 1/3 the volume of the pond through the bog each hour. a 3,000 gallon pond needs a 1,000 gph pump for filtration.

The volume of water should pass through the pea gravel not over it and check to see if the moving water is flushing pea gravel out of the bog into the pond {this should not happen , reduce flow to stop it}

 Plant you bog plants with out soil in the pea gravel.. enjoy your water garden!!!

----------------below is the updated version of bogs-------------

The Bog and Waterfall

Topics Covered: Algae, Bog, Bacteria, Filtration, Construction, Lapping Liner and Salt.

An Aerobic Bog is nature’s way of cleaning up water.  It consists of:

1) Slow moving Water

2) Lots of surface area for Bacteria to breakdown nutrients and plant fiber.

3)  Plants that survive well in an area that is saturated with water.

Controlling GREEN WATER is the Bog’s job. That green pigment forming in a pond is really a small plant called Algae.  Algae can be suspended in the water, attached to rocks and plants or can be long and stringy in moving water.  It only grows abundantly when there are all of the following conditions:

1) EXCESSIVE NUTRIENTS, (N,K,P,)

2) SUN LIGHT

3) WATER

4) WATER TEMPERATURES ABOVE 48*f

Since the above Items 2,3,4 are things we want in a pond only 1) “EXCESSIVE NUTRIENTS, (N,K,P,) really need to be addressed.  The obvious is Nitrogen (N) also found in concentrations as Ammonia or Urea.  Most of the time this is caused by excess numbers of fish in regard to how much Nitrogen gas can be vented from the water.  If there are no plants to use up the Nitrogen, then the only way to remove this gas is by aeration.  A high level of usable Nitrogen causes plants and algae to grow.  The other two nutrients of interest is Phosphate (K) and Potash (P), They are the result of protein breakdown, either by your fish ingesting food or food falling to the bottom of the pond and being digested by bacteria.  These two are also called salts because they do not evaporate or leave the pond as a gas.  These two salts are needed for plant growth.

For all three nutrients (N,K,P,) Bacteria is essential in the detoxification and converting of complex proteins and Urea into usable or easily removable elements. Different Bacteria work on different complex structures.  Some work in the presents of air (oxygen aerobically and other work in the absence of oxygen (Anaerobic).  Plants for the most part do not care if there is oxygen available or not, but Fish DO need Oxygen.  So the goal is to encourage (friendly to fish) Aerobic Bacteria, to do the work. 

The Friendly Aerobic Bacteria (FAB) need:

1)  a place that has moving moisture (water)

2)  a place to cling to (lots of non-toxic surface area),

3) Temperatures above 46*f,

4) it has to be DARK (no UV light),

5) a constant supply of complex Nutrients. 

One of the places were FAB’s do well is in bogs and streambeds.  The FAB’s cling to the under sides of rock, gravel and plant roots.  The slow moving water currents  bring the complex nutrients to the FAB’s and then remove the byproducts either over small falls or past plants. 

The bogs we recommend to clean up pond water have all the different filtration methods combined in one convenient area:

1)      Mechanical filtration (Rocks and Plant roots)  that screen out the large particles

2)      Biological filtration (FAB’s)

3)      Vegetative filtration (plants)

When planning a bog consider a location next to your pond. This could be a stream bed or at the top of a water fall or better yet a separate bog with a separate pump supplying pond water to it.  The bog area should be about 1/3 the surface area of your pond.  It should be located higher in elevation than the top of the water in your pond.  You want to pump up from your pond and allow the water to trickle back down into your pond. For clearification of order of construction the pond should be built first then the bog and waterfall.  It is not necessary to have a hill or berm for a waterfall to get the benefit of a bog filtration area. You will need a space just higher than the surface of your pond.

Sometimes when purchasing your pond liner if you get a few feet more you can sometimes get enough extra liner from the corner area of your pond to use to build your bog.  Every area that may have pond water on it must have pond liner under it. This goes for streams, bogs, and water falls. Save any extra liner for additional projects later.

Bogs are not deep but rather shallow places usually only 4 to 6 inches of washed pea gravel.  The sides of the bog are higher because in a few months you will have some damming of the waterway.  Over time the water level in your bog may raise 4 to 5 inches, you will need to take this into account when building the sides of your bog.

One of the misconceptions of a bog is that it is only water, rocks and gravel.  The bacteria will thrive and the pebbles and gravel will mechanically screen out much of the debris but this alone will not remove the Nutrients (N,K,P,) The system needs Plants to become more efficient than the text book biofilter.  Granted the first part of the bog system sounds like the rocks, water, FAB’s, do all the work, but they are only half the story in getting the water nice and clear.  It takes the plants to finish the process.  There are several different kinds of plants that work well in a bog and not just limited to the ones that are called “wetland plants”. Some of the plants that require lots of watering also do well in the bog.  Plants like day lilies, Astelbe, and Hosta’s also do well as bog plants.  You will want to wash all the dirt off of the roots of these plants and plant them in the wet pea gravel bare rooted. This is a hydroponics system.. you will not have to fertilize the plants because your fish are doing that for you.  You will not have to worry about watering the plant because 1/3 of the volume of water from your pond is being pumped into the bog every hour, 24 hours a day 7 days a week.  The only time you would even consider shutting off your pump to your bog is when the outside temperatures drop below freezing.  Also weeding is easy because you are using pea gravel!

Some of the plants that need a lot of water but are not considered bog plants need to be planted a little higher in the pea gravel but allowing their roots to dabble in the water just a little.

Where the bog flows back into the pond we will need to seal this area between the two pieces of liner.  It is very important that there is a rise above the water level line to over lap the bog liner over the edge of the pond and apply a few beads of a 50 year silicone caulk (that does not clean up using water) between the two liners above the water level line.  Think of it as shingles on a roof, as long as the gutters don’t back up water does not flow under the shingles no does the water from the pond flow back up and out between the two liners.  Do not just smear the silicone like a big pancake but rather apply thin ribbons or strings of caulk across the surface of the liner parallel to the water level line. (we do not want to make it look and work like a soda straw.)

Pea Gravel: Pea size pebbles that you will need to wash well before shoveling it into your bog. (Just because it says “washed Pea gravel” does not mean it is free of silt and sand)  Shovel the washed pea gravel into the bog up to the level of the outflow or about a depth of 4 to 6 inches.  Stack rocks around the edge of the bog to cover the liner.  The pipe or tubing can be hidden in the rocks and in the gravel. 

Water flows through the bog should be about 1/3 of the total volume of your pond per hour. Or the entire volume of your pond goes through your bog every 3 hours for small ponds, every 4 hours for ponds about 3000 gallons and every 6 hours for ponds up to 10000 hours.  Or a different way of thinking about it; the entire volume passes through your bog 5 to 8 times in a 24 hour time.  If you have pea gravel being washed out of your bog into your pond you have way to much volume or flow and will have to reduce the amount of water flow through your bog. Remember the water has to pass through the pea gravel neither over it nor so forceful it  pushes the gravel out of your bog.

A small waterfall may be built on the overflow by spraying a small line of “Great Stuff™” foam and placing a flat rock onto the foam.  The foam can be sprayed on the liner and under the rocks to form a seal.  Your entire water fall can be built using the foam instead of using Concrete, mortar mix or cement. The rule of thumb is you can stack rock and foam one foot of elevation  per day and then you will have to wait 24 hrs for it to set up.  Start with a new unopened can of foam each time you begin construction on your waterfall.   (allow at least 3 hours for the foam to dry prior to turning on the water) 

Look at your bog the edge of the liner should point up all the way around the bog except where it overflows back into the pond. To be one step better in construction the liner around the outside of the bog should be tipped up and folded back into the bog, this will stop any “wicking”.  The overflow area the liner should point down into the pond. (remember the shingles on the house example).

Turn on your pump that is protected inside two mesh baskets so it looks like a clam in its’ shell and has the sponge filters removed. Plant you bog and add non-iodized salt or sea salt; 4 lbs per 1000 gallons of pond water or 1 cup per 100 gallons. This needs to be done at least two times a year once in the fall and once in the spring.  This concentration will not harm your plants and will help your fish survive.

mark@snursery.com for more info if you need it!  Pond Place 2209 Simpson Ave. Hoquiam WA.

mark@ snursery.com Pond place  mailroom for answers or questions about this form

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