Basics of Planning a Pond
There are at least three basic types of pond, the natural in ground pond, the formal / semi-formal in ground pond and the raised pond, which by it’s very nature tends to be formal or semi-formal.
Most of our planning recommendations will apply to all three styles. Our very first recommendation is: Make it bigger. We have yet to hear from a customer telling us that they wish they had made their pond smaller. Almost everyone comes in sometime in the first year or two and tells us they wish they had made it bigger. Remember, doubling the size does not double the price. Also the larger the pond, provided it is done correctly, the LESS work it is to maintain. The bigger a pond is, the more it acts like a self-sustaining ecosystem.
Next, after you decide on the type of pond and rough size that you want, you need to decide on location and orientation. Ask yourself, when sitting outside enjoying the pond, just where you will be sitting. Put the waterfall opposite from there so that you look at the falls. If you are going to be sitting on a deck, don’t back the falls up to the deck.
Now, where is your electric service for the pond? It should be at the other end from the falls. If running new or upgrading, you should have your electrician give you at least eight outlets for any pond over 1000 gallons, and this is absolutely necessary for any pond over 3000 gallons. Ideally, this would be two 15 or 20 amp circuits with four outlets on each circuit. You won’t have a lot of power consumption on the circuits, as most of what you will be plugging in is very low draw. Why eight? With a 3000-gallon pond you have at least one, possibly two main pumps. You have two ultraviolet lights. You should have an air pump. You will probably add underwater lights at some point and maybe a spitter or fountain. Wow. We just used up seven of our eight outlets.
You will automatically have this with the raised or formal pond, but with the natural pond it is of critical importance to have the edge slightly raised above ground level. You can feather this berm so it is not noticeable, but you do not want runoff from the yard to go into the pond bringing with it pesticides or fertilizers that have been put down by you or any of your neighbors.
On the natural pond we also recommend you dig a shelf about 12” deep and about 15” to 18” wide all the way around the pond. This gives you a base to stack rocks on to hide the liner on the edge of the pond. Plants can also then be planted bare root in these rocks.
Now to the materials. We will only sell and only recommend 45 mil U.S. made EDPM rubber liner. Hard plastic shells don’t last and are too hard to install correctly. PVC liners only last 7 to 10 years. 20 mil liners cut or puncture too easily. The Chinese made EDPM doesn’t hold up over time. (Yes, I tried it once. Had to replace it three years later. Learn from my mistakes!) To size your liner, start with your widest width. Add the deepest depth. Add the depth again. Add 1½’ for the overlap on the side. Add 1½’ for overlap on the other side. This is the width of the liner you need. Now do the same for the length and this is the size liner for your pond. We recommend a maximum depth for this area of 3’ to 3½’. You may read books or articles saying a pond should be deeper, but that applies to much further north than we are. For winter weather here, 12” is deep enough, but we recommend the 3’ depth for predator protection and coolness in the summer. We do recommend use of an underlayment. We sell it by the foot off of a roll but many people just use old carpet instead. We have seen sellers say not to use carpet, that it will rot, but we have worked on and pulled up 20 year old ponds where the underlying carpet was still there. Many books will tell you to use sand under your liner to level and pad. We vehemently disagree with that. Sand is abrasive. Use peat moss. It’s soft and fluffy and compresses well and won’t wear a hole in anything.
Pumps. Once you know how big your pond will be you can size your pump. Absolute, absolute minimum is to filter your water at least once an hour. Keep in mind that pump ratings are before figuring head pressure, so a 1500-gallon pond should have at least a 2000 gallon per hour pump. More is better. We filter our display pond and most of our holding tanks six times an hour. We will try to talk you into a pump or pumps that will filter your pond two or three times an hour. The two big differences between good pumps and cheap pumps is, one, how long they last (We have many pumps here that have been running for ten years and more) and, two, how much power they draw. If you save a hundred bucks buying a pump that costs you an extra 10 bucks a month in electric to run, you haven’t saved anything. Years ago, external pumps were more reliable and efficient, but over the last fifteen years or more, submersible pumps are now both more reliable and more efficient. For larger ponds we recommend two medium pumps rather than one big one. Two 5200 gph pumps use less electricity combined than one 8000 gph pump by itself, give you more total flow AND give you some redundancy so you still have filtration even if one pump goes out.
Again, depending on which type of pond you have decided to go with, you should plan for either a waterfall filter, a bog filter or a pressurized filter. What is most important is that it is big enough for your pond. Realize that all manufacturers over-rate their products. (Ford says my truck gets 23 mpg. Yeah, right.) We generally say start at about two-thirds of the rating as being more realistic, and again, you can never have too much filter. We have a nice separate write-up on filtration for you to refer to.
We strongly urge you to use a skimmer. It will make pond maintenance easier and thus pond ownership more enjoyable and will help your pump last years longer by better protecting it. Skimmers come in all prices and qualities. We recommend the Savio as far and away the best designed and best made available. It is easily many times better than any others on the market. If you want a cheap piece of crap, go on-line and buy it, we won’t sell it to you. The Savio skimmer also has the advantage of allowing you to install uv lights directly in the skimmer, saving plumbing hassles, making for a more elegant and better looking installation and making changing the bulbs easier.
We cannot emphasize too much how much we strongly, strongly urge you to install an ultraviolet light on your pond. We have no tank or pond at our shop containing fish that we don’t run a uv light on. If sized and installed correctly, they not only help control green water algae but help to cut down on any disease organisms in your pond.
With a typical medium to large pond you will have a skimmer at one end pulling water off of the surface and your waterfall / bog / pressurized filter putting water back in at the surface at the other end, filtering the top foot or less of water over and over as the bottom becomes gradually dead, de-oxygenated and collects debris. By adding an air pump and airstones you create a series of currents pulling water and debris off of the bottom and up to the surface where it gets aerated and filtered. This can also be accomplished with bottom drains, but we do not recommend them as they are more expensive, the plumbing to install them far more complex and because you are penetrating your liner in the bottom of the pond you have a serious danger of an eventual leak.
When designing your plumbing remember not to use sharp 90° turns. Best is flexible hose that can do a wide sweeping curve, next best would be to use what is called a sweep 90° fitting or use two 45° fittings in a row. Every hard 90° fitting in your plumbing will cut your flow rate by 5%. Measure your estimated piping for both total length and height of rise. This will give you your head pressure to use in sizing your pump. Every foot of height difference between the surface of the water and the height of the spillway (not where the water enters but where it leaves) is one foot, then every ten feet of pipe length equals another foot of head pressure. Get this total, then check it against your pump manual to see how much water to expect at this head pressure. Then subtract 5% of that figure for each 90° fitting and 2% for each sweep 90° or double 45° to get your actual pump volume. For pumps up to about 2000 gph you need at least 1¼” hose / pipe, for up to 3500 gph you need at least 1½” hose / pipe and for over that you need at least 2” hose / pipe. Too small a hose / pipe will put excessive back pressure on your pump and seriously reduce your achievable flow.
We will be happy to go over your design and materials list with you before or during construction and give you our advice on it. Our goal is for your pond to work well and be as easy as possible to take care of so you spend your time enjoying it instead of fighting with it.