A Pond Bog Filtration System – Manifold Retrofit.

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Aquaponics 4 You

Provides Clean Look And No Place For Mosquitoes.

Pond Bog Filtration15 years ago when we moved into our new house we took all the Koi from our old pond with us. In the new pond that we constructed, which was an integral part of the deck we were going to install, we decided to go with a bog filter on either side of the pond. Over the years we tried different ways of changing the filtration to reduce mess and cleanup.

Whatever we did though it always resulted in a messy clean out every year or so, which took somewhere in the neighborhood of three quarters of the day to complete. This year we decide to go a different route when we saw a YouTube video by the Pond Digger where he installed a manifold under a layer of gravel. Below is a video of how we accomplished this and how it worked out along with the video from the Pond Digger where he actually shows you how to build the manifold system.

The only differences between the two systems is shape and size of the manifold and the amount of water flowing through the system. His system was low-flow whereas ours has to handle a larger volume of water in order to operate the waterfalls properly. From what you’ll see in the video this change in volume is really no big deal since the system handled it quite well. Another difference in the two systems is that we created a manifold with no dead ends by looping everything together to give it a more circular flow.

We presently have an 1100 gallon per hour pump running the system but will shortly be switching to a Laguna 1350 gallon per hour model (See update below). We think that this new model will give us the ability to more easily keep it clean and remove it from the pond when necessary.

Here are a few tips that we learned along the way.

  • If you’re building a retrofit system as we did, use a larger smooth stone (Vigaro pond stones) in the bottom to help level the manifold and then pack more of the same type a rock around the sides and in the center before pouring on the pea gravel.
  • Whether you’re getting your pea gravel in bags from Home Depot or in bulk from the landscape supply place please wash it thoroughly. You really don’t want the rest of your pond looking like a mud hole after you turn the system on.
  • Since the manifold is a closed system it will hold air during its initial startup. You can alleviate this by drilling small 3/16 inch holes in several areas so the air can leak out. Air being trapped may not be a problem in a low-flow system but this is in the higher flow system.
  • When you start gluing up the manifold with PVC cement start at one end and work towards the other to ensure that everything will line up. If you start gluing pieces up in sections I can almost guarantee that you wind up with an alignment problem meaning that you won’t be a little fit pipe inside the fittings when you get to the end.
  • Again since this is a closed system once the pump shuts off the water in the bog will be siphoned back into the pond (unless a check valve is installed) and this will continue until it siphons everything out down to the manifold. You probably don’t want this to happen, so at whatever level you want the water to stop (1/2 inch to 1 inch below the gravel) drill a small hole (3/16”) in the tubing or fitting so that once the water gets below that level it will suck air and break the siphon.
  • When placing any plants directly into the gravel bed wash the roots off thoroughly prior to inserting them. The dirt is not needed and it will only cause grief in your pond and bog.
  • If you have a waterfall in the system such as ours place a fine mesh net over the spout to collect any refuse that that may flow out when you first turn the system on. You’ll find that pieces of PVC and small pieces of vegetable matter magically show up when you turn the system on. It’s best to catch these before they go into the pond.

There you have it the way we implemented a really great idea that we saw on YouTube from the Pond Digger. Don’t be afraid to experiment with the design of the manifold to suit your system and needs after all you are the one that has to live with its outcome.

Enjoy the videos and thanks once again to The Pond Digger for the great idea.


Manifold Retrofit.

(Our Implementation)



Basic Manifold Construction.

(Original Pond Digger Video)



Update On New Pond Pump.




1 Month Bog Update



3 Month Bog Update




1 Year Bog Update



2 Year Bog Update





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