Saturday, November 28, 2009

Positioning A Grow Bed

So it's time to mount the grow bed. However, there are a couple of things to consider before you do it.

Location - You are going to need sunshine, so pick a spot that will get a good amount. Also, keep it close to the pond and close to the pump. Too far and your pump might not get the flow you expect. You will also have more pipe that you will have to bury, and nobody likes digging except maybe Satan.

Height - The output will be using gravity as the main force to return the water to the pond. The drain will be at the bottom of the grow bed and needs to be well above the water line of your pond. Make it as high as possible, but keep the top of the bed at least a couple feet below the fence-line or your neighbors might complain. And remember that creating too much head from your pump will lessen its output, so don't go too high.

Why the height of your grow bed is important:
It is important to provide good water circulation inside your pond for aeration. Aeration is much more effective with good circulation. In fact, at least one study that I have read says that circulation is the best form of aeration. But at minimum, by moving deep water to the surface continuously, you will increase aeration dramatically. So, in order to create a good flow for circulation inside the pond, get the bed off the ground as high as you can without causing negative effects, such as no access to the plants, or creating too much head for your pump.

Image shows a 4 foot drop in my configuration.
Combined with the first line(which has about a 6 foot drop),
this creates a great circular water current in the smaller pond.

So how high should it be?
There are too many factors to consider for me to give an exact height. Every system will vary. How many beds you have, number of ponds, aeration method, type of drain, and pond size are all things that will determin how high you mount the grow bed. If you just have a single pond, and you have an aeration system that can create good circulation, such as the aeration method I use in my larger pond, you can keep the grow beds fairly low just a foot or two above the water line. But if you are using a bubbler, any other method of aeartion, or you have more than one pond, you will need extra height. The higher, the better. If in doubt, go higher.

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