Garden Ponds

I have a soft spot in my gardening world for garden ponds, as many of my readers know.

Last week, I spent a day taking a contractors course in constructing modern water gardens.

What I learned can be summed up in a simple philosophy and a very few words.

Copy Mother Nature

I do not know how many times I have said just copy Mother Nature (or something similar) in my own soil-based gardening world so when the course instructors said that, I confess I was hooked. Copy old Mom and everything will turn out well.

As it turns out, when you examine what nature is doing in her garden ponds, we can duplicate those things with very little effort. And, as I drooled over the slides of wonderful ponds, I confess I’ was prepared to start spending the effort to work with nature on my garden ponds and designs.

Think Modern Systems

The first thing you have to do is shuck off some of the older notions of building garden ponds or pondless waterfalls. Like many things in this gardening world of ours, we’ve learned some things about garden ponds in the past few years that are not yet described well in our gardening books and magazines.

Look at what is happening in nature and then copy that.

An Old Myth Exposed

For example, books always say that covering up the pond liner is a no-no. For sure, we want to protect the exposed edges from sunlight so it doesn’'t degrade but the old advice was that the liner inside the pond should be bare. Now, the word is to lay rocks and small pea gravel onto this liner to protect it and provide a home for beneficial bacteria to work to help keep our water clear.

Makes sense to me, have you ever seen a pond or creek in the wild without rocks or sand or some substrate to protect working bacteria ? Me neither. There is of course a way to lay these rocks and gravel down so as not to damage the liner but once they are laid down, the pond becomes one step closer to being a full bio-filter.

Water Management

Because that’'s the next step in pond management. If you have fish and wildlife in your garden ponds, then you are going to have to install a two step filtration system. Most of my existing garden ponds were designed for plants; I do not have large fish in them but as soon as you put fish into a pond, and you really want to do this for sure, then you have to go to filtration.

Mother Nature Filters Her Water

I can hear you saying - Mother Nature doesn’t filter her water.” Well, check out all the swamps, bogs and wetlands around us; those are nature’s filter systems and they keep our water clean and pure. When you remove wetlands and bogs, you'’re removing nature’s filters.

If you do not have filtration when you have running water, the pumps very quickly clog up and cleaning out those tiny screens is a royal pain in the anatomy. So, what I learned was that a two step filtration system works best.

First Filter

The first step is a large particle filter or pond skimmers. This is like a furnace screen that removes all the floating junk in the pond. All the leaves, bits of grass and stuff that is attracted to a pond like iron filings are attracted to a magnet can be removed by a large-particle filter. Clean this box out once a week (or more when leaves are falling or you’ have pointed the lawn mower discharge into the pond by accident) and much of the problem disappears.

Second Filter

A second filter, called a biological filter, acts to balance the water chemistry. Things like nitrates are absorbed and used by bacterial cultures inside this filter. While the construction of such a filter is pretty simple and its operation is equally easy, it turns out that this is one of those things that bogs and swamps also do for our natural streams.

Copying nature, we build or purchase a large enough biological filter to handle the size of our garden ponds and then we can have lots of fish.


To make this entire system work, we use a pump installed in the skimmer filter to pump the water through hoses to the other end of the pond and through the biological filter. From this biological filter, the water runs into the pond to start the process over again. The algae and bacteria on the rocks in the pond help to filter the water and keep it crystal clear. What is interesting is that when this system is all set up properly, it works like a charm and provide a wonderful pond setting. The key is to size all the component pond pump parts properly.

Pump Rating

The pump should be capable of moving all the water in the pond every two hours or less. If you have a 4000 gallon pond, then the smallest pump you can use is one rated for moving 2000 gallons of water per hour.

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