Bottom drains are often intimidating to the beginner due to a fear of leaks. T his is often enough to overshadow the realization of how integral and important they are to both water quality and reducing maintenance. It's a huge "should have" to face down the road when just a afternoon of work could have made your pond so much better
Bottom drains just make sense. You wouldn't let feces break down naturally in a rabbit or budgie cage so why is it any different in a fish pond? As beautiful as they are, Koi do defecate quite a lot. You need to keep your pond's bottom clean with of both excrement and other organic buildup. A bottom drain is simply the best way to achieve this
Bottom drain pundits are generally those who don't' know how to install a drain, don't understand what they provide or just don't want to go through the effort. The advantages distantly eclipse the disadvantages and are impossible to refute
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The term "bottom drain" is really a misnomer. They should be more aptly referred to as a "bottom filter feed or return ". While a pump in the pond is aesthetically unattractive and can't remove large debris, a 4 inch bottom drain will remove everything, including large leaves, as it continually vacuums your pond
Parts of a Drain
Bottom drains are comprised of 3 parts. The sump or body, the flange and the Dome. The flange is used to affix the liner to the sump to create a water tight seal
The dome forces the drain to draw water from the pond's bottom thereby pulling debris with it. Always install the dome. The draw radius of a drain is about 2 feet so it is important to bowl the bottom towards your drain(s)
Attached to the drains body is a 4 inch neck which will connect to pipe and/or flex hose. This is the conduit to carry debris to your settlement tank |
The greatest fear people have in regards to bottom drains is that their pond will leak. When properly installed, the chances are very slim that there will be any problems. Ultimately, I hear more news of people pumping their ponds dry with submersibles then I ever do about bottom drains leaking
As for the actually 1-2-3 of getting the drain installed, it's straight forward for even the average Do It Yourselfer
A hole to house the drain is dug in the deepest section of the pond. The ponds bottom should be bowled to this location with a decent slope - this causes debris to move towards the drain via gravity. A trench is also dug which leads to the settlement tank. The drain and associated plumbing is laid into place
The liner is installed over over the drain. It is very important to make sure you have enough liner around all the sides of your pond before you cut the drain in. An "X" cut is made over the sump of the drain. Reach in make sure both the liner and sump are both clean and dry. Place some glue on the sump lip, then press the liner down and flatten it out, smoothing out any wrinkles
Put the flange down into place and proceed to screw it in to the sump. This is your seal so take your time and get it right. Trim the liner inside the sump and then add another bead of glue. The liner actually acts as a rubber gasket
Your drain is now installed - enjoy the reduced maintenance, better aesthetics and best of all, superior water quality
see the pictures below
TIP - remember, your drain will likely have "airlock" when you first fill up your pond. Flow rate will be very poor. Close the gate valve, drain the vortex completely and then open the gate valve. Water with air will rush in. Repeat until you don't see any air pockets within the intake water (3-5 times)
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In most cases, people building their first pond do not install a bottom drain and they soon grow to regret it
Without a proper bottom drain you will probably fight with a clogging pump and struggle to hide the power cord and tubing from sight. Additionally, submersible pumps consume more power and do not last as long as external pumps
Aesthetics aside, you will shocked at the amount of debris that has built up when you perform your first pond clean out. As the fish get larger, the pond clean out becomes quite an ordeal and stressful for both yourself and the fish
A bottom drain will promote maximum re-circulation and water quality as it vacuums the pond floor. Without it, accumulated debris often makes its way back up into the water column creating turbidity issues
In short, a bottom drain needs to be considered as an essential component of any pond
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The drains have been roughed in and the collar is not yet installed. If you look closely, you can see the hump in the middle of the pond which will steer debris to the drains |
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The flex hose has now been installed and attached to the drains with rubber couplers |
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Both drain lines feed 1 vortex. Inside the vortex we installed gate valves so the flow can be controlled from each drain |
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Try to get he drain as level as possible being cageful to make it fit with the surrounding soil. A couple bags of concrete to hold the drain in place is a good idea. Install the membranes and then perform an "X" cut - not too large. Clean the rim of the bottom drain and the underside of the liner. Make sure it is spotless, dry and that no geosynthetic will interfere with the seal
Apply the glue to the drain, underneath the liner, then press the liner into place on the drain body and even it out so there are no wrinkles. Align the flange and screw in your first screw. Finding the first hole can be a bit of a challenge, depending on the type of drain you can mark the drains body to make this easier . After the first screw is in, do the hole next to it. After that, alternate the holes much like you would with a car tire
Trim the excess liner away. Apply another bead of glue around the drain body, liner and flange connection
Remember, take your time, this is not a 5 minute job ! If you are too nervous to install your drain, we do provide that service and if your well prepared it won't take more than 2 hours
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When you fill up your pond for the first time, it is likely that the bottom drain line will be "air locked". As a result of this, very little water will enter the vortex. To rectify this problem, close your gate valve to isolate the vortex. Completely pump or drain out the vortex. Open the gate valve. Water, accompanied by air, will rush in. This may need to be repeated a few times until you don't see any air/water mixture coming in
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Always install the dome after the pond is filled with a couple of feet of water . If you install it before filling, air will be trapped under the dome. With some water in the pond, the dome can be turned upside down under water to remove the air before being installed. Alternatively, you can drill a tiny hole at the top of the dome so air can escape
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Never glue the dome on the stem . Although unlikely, you may have to clear a clog one day and this might require removal of the dome |
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