Building a "wildlife pond"
Discussion
I've decided I'd like to build a pond in my back garden. I've never owned or built a pond before, although I do have previous experience with freshwater aquaria so I do have a decent understanding of the way aquatic systems work (nitrogen cycle etc). I thought I'd describe roughly what I've got in mind, and perhaps people can tell me where I've got things wrong!
Firstly, a picture of the location:
The location is in a sunny spot, and not overhung by any trees - although there are large mature deciduous trees in neighbouring gardens, so leaves will always be a slight issue. There used to be a large dead willow tree there about 5 years ago, so there are the rotting remains of the stump - this should make it easy to hack through any roots that I find when digging.
The tall clump of grass will stay, but the cat will have to move! (Although she's useful in the picture for scale...) As you can see, I've laid out a hosepipe in the rough shape I'm considering, although I've stretched it out slightly further on the left-hand side since I took the picture. I think it's about 3m long and not quite 2m wide.
My plan is for a "wildlife" pond, with plenty of plants to encourage insects, amphibians etc. Am I right in thinking that fish should not be part of the picture? I'd like a couple of goldfish in there, but would they eat all the other creatures that I'm interested in, and/or their eggs, larvae etc?
I'll be going for a flexible liner. I think I've read that butyl is best and lasts longest, albeit expensive. Is that correct?
I want to reach a depth of about 2 feet in the middle, with "shelves" at about 12" and 6" with various plants. I have a vague idea to make the right-hand end shallower - perhaps only 3" or 4" and grow bog plants in that area.
I'd like to bring the lawn right up to the edge, rather than have rocks or any paving around the edge. My plan is to embed some kind of flexible barrier around the edge, to about the level of the lawn soil or perhaps a fraction higher. The pond liner would loop up over this, with the intention that no water would be able to run off from the lawn and pollute the pond with excessive nutrients. A further 6" or so of liner would then be buried at an angle underneath the turf - I'd lift the turf to bury it and then replace. Does this sound like a plan that will work?
There will, of course, have to be an area where the edge allows creatures to crawl in and out of the pond. I plan that the rear edge (near the tall grasses) will provide this, perhaps with some pebbles or shingle in that area.
I want water movement, so I plan to have a low voltage pump driven by power from my greenhouse about 8 metres away, and bury the cable under the lawn. I think I'll put the pump at the bottom of the deepest part, and have the water return via a hose into the shallowest part. My thinking is that this will help with oxygen distribution, and keep temperatures down in the shallow end. It'll be quite gentle, but hopefully enough to make a slight "babbling" sound. Will the water movement result in excessive evaporation?
What plants should I have? I'd like to have a small water lily if possible - should that go in the deepest bit? Should I plant all my plants into baskets rather than direct into a substrate? For that matter, what substrate (if any) should I have in the pond? Is ordinary garden soil suitable for planting (my soil is fairly heavy)? What marginal plants do you recommend?
Filling the pond: Ideally I'd prefer to use rainwater, but I think the quantity will be far more than I can provide. I'm guessing it'll be between 1 and 2 cubic metres, so far more than my water butt can provide. Is it okay to fill with tap water, or will that charge the pond with too much nitrate/phosphate? Should I use a tapwater conditioner (e.g. Aquasafe)? Do I need to measure how much water goes in? I could do that by timing how long it takes to fill and compare with how long it takes to fill a bucket.
And finally, do I need to do anything to help wildlife to find the pond? The location isn't perfect, because it's a bit isolated in the middle of my lawn. So will I need to put frog spawn in there or will they find it? I did find a newt in my greenhouse a few nights ago, so they're in the vicinity!
Any help, suggestions, warnings, etc very gratefully received!
Firstly, a picture of the location:
The location is in a sunny spot, and not overhung by any trees - although there are large mature deciduous trees in neighbouring gardens, so leaves will always be a slight issue. There used to be a large dead willow tree there about 5 years ago, so there are the rotting remains of the stump - this should make it easy to hack through any roots that I find when digging.
The tall clump of grass will stay, but the cat will have to move! (Although she's useful in the picture for scale...) As you can see, I've laid out a hosepipe in the rough shape I'm considering, although I've stretched it out slightly further on the left-hand side since I took the picture. I think it's about 3m long and not quite 2m wide.
My plan is for a "wildlife" pond, with plenty of plants to encourage insects, amphibians etc. Am I right in thinking that fish should not be part of the picture? I'd like a couple of goldfish in there, but would they eat all the other creatures that I'm interested in, and/or their eggs, larvae etc?
I'll be going for a flexible liner. I think I've read that butyl is best and lasts longest, albeit expensive. Is that correct?
I want to reach a depth of about 2 feet in the middle, with "shelves" at about 12" and 6" with various plants. I have a vague idea to make the right-hand end shallower - perhaps only 3" or 4" and grow bog plants in that area.
I'd like to bring the lawn right up to the edge, rather than have rocks or any paving around the edge. My plan is to embed some kind of flexible barrier around the edge, to about the level of the lawn soil or perhaps a fraction higher. The pond liner would loop up over this, with the intention that no water would be able to run off from the lawn and pollute the pond with excessive nutrients. A further 6" or so of liner would then be buried at an angle underneath the turf - I'd lift the turf to bury it and then replace. Does this sound like a plan that will work?
There will, of course, have to be an area where the edge allows creatures to crawl in and out of the pond. I plan that the rear edge (near the tall grasses) will provide this, perhaps with some pebbles or shingle in that area.
I want water movement, so I plan to have a low voltage pump driven by power from my greenhouse about 8 metres away, and bury the cable under the lawn. I think I'll put the pump at the bottom of the deepest part, and have the water return via a hose into the shallowest part. My thinking is that this will help with oxygen distribution, and keep temperatures down in the shallow end. It'll be quite gentle, but hopefully enough to make a slight "babbling" sound. Will the water movement result in excessive evaporation?
What plants should I have? I'd like to have a small water lily if possible - should that go in the deepest bit? Should I plant all my plants into baskets rather than direct into a substrate? For that matter, what substrate (if any) should I have in the pond? Is ordinary garden soil suitable for planting (my soil is fairly heavy)? What marginal plants do you recommend?
Filling the pond: Ideally I'd prefer to use rainwater, but I think the quantity will be far more than I can provide. I'm guessing it'll be between 1 and 2 cubic metres, so far more than my water butt can provide. Is it okay to fill with tap water, or will that charge the pond with too much nitrate/phosphate? Should I use a tapwater conditioner (e.g. Aquasafe)? Do I need to measure how much water goes in? I could do that by timing how long it takes to fill and compare with how long it takes to fill a bucket.
And finally, do I need to do anything to help wildlife to find the pond? The location isn't perfect, because it's a bit isolated in the middle of my lawn. So will I need to put frog spawn in there or will they find it? I did find a newt in my greenhouse a few nights ago, so they're in the vicinity!
Any help, suggestions, warnings, etc very gratefully received!
Sounds good. If you are going for a natural pond and no fish then I wouldn't bother with the pump. It will just clog up and and need constant cleaning if its just a small one. Make the shelves nice and wide to ensure that any plants that are on the shelves don't slip down into the middle. I built something similar and created a sloped bank into the water which I cemented and placed cobbles into. This allows birds to use the pond as a bird bath and other creatures to get in and out. You should be able to keep a few goldfish in it once its established with out the need for filtration. If you decide to go down the route of a pump then you may as well get a filter as well. Concealing it will be the issue though.
Sounds like a plan although personally I wouldn't put it bang slap in the middle of the lawn. Fine if you want a formal goldfish pool but for a wildlife pond, which is what you want, I'd position it half on the edge of the lawn so creatures can go off into the shrubs and plants. Also a bit of shade will help reduce green water, which you will get in the first year or two. Damson flies and dragon flies should find it no problem, as will frogs, mosquitoes, grass snakes, herons and in my case even north American black mink! If you can go deeper than 2' so much the better 24" is the absolute minimum for wildlife and most lilies require that depth of water over them so once they are in a basket you'll only have 12" water over the top of the lily. Plants like elodea and hornwort are good and I'd also look at water hawthorn it has strap like leaves and white scented flowers and is almost evergreen, one of the few pond plants that actually puts up fresh leaves in winter. As for goldfish I can't see the problem (see my comment on depth) in my experience a few goldfish will not trouble the creatures but some people get sniffy about them. If you are a purist you could put in a few sticklebacks but what's the point?
Do realise that onc eyou've embarked on this there's no turning back as you will have a bloody great hole in the garden and you will get; green water, blanket weed, duck weed, dead frogs, dead fish, herons attacks and you'll embark on a lifetime of wanting a bigger and better pond but if that's what you fancy good luck!
Do realise that onc eyou've embarked on this there's no turning back as you will have a bloody great hole in the garden and you will get; green water, blanket weed, duck weed, dead frogs, dead fish, herons attacks and you'll embark on a lifetime of wanting a bigger and better pond but if that's what you fancy good luck!
Sounds good to me. The edging design is what I was going to recommend. You might want to put a collar of concrete underneath where you want the actual edge to be. I didn't, but nobody attempts to stand too close to my edge!
The frog botherers insist on no fish. Personally, I would not put ornamental species in, but if you can get hold of a few sticklebacks they would make an interesting addition and prevent it becoming a handy breeding ground for mosquitos. Besides, my Ladybird Book Of Ponds had sticklebacks in it, so it just seems wrong to me to exclude them!
It's a wildlife pond. Natural ponds go green in summer, and it's likely that yours will too. I'd accept that, but some people expect their wildlife pond to be as clear as an artificially managed koi pond at all times. Some plants with floating leaves to shade the water column will help with water clarity.
Tapwater will be fine. Fill it and leave it a few days before you put anything in. If you buy plants for it, they will probably bring plenty of life in with them, and while the chlorine won't do the plants any harm you want whatever comes in with them.
I would be wary of Canadian pondweed or anything sold as an "oxygenating plant". Unless you fancy spending your life dragging the bloody stuff out again. If you can avoid getting duckweed or azolla in there, that would be a good thing. If the place you buy your plants from has either of those floating around the tubs the plants are in, you can be pretty sure you'll be taking some of it home.
The frog botherers insist on no fish. Personally, I would not put ornamental species in, but if you can get hold of a few sticklebacks they would make an interesting addition and prevent it becoming a handy breeding ground for mosquitos. Besides, my Ladybird Book Of Ponds had sticklebacks in it, so it just seems wrong to me to exclude them!
It's a wildlife pond. Natural ponds go green in summer, and it's likely that yours will too. I'd accept that, but some people expect their wildlife pond to be as clear as an artificially managed koi pond at all times. Some plants with floating leaves to shade the water column will help with water clarity.
Tapwater will be fine. Fill it and leave it a few days before you put anything in. If you buy plants for it, they will probably bring plenty of life in with them, and while the chlorine won't do the plants any harm you want whatever comes in with them.
I would be wary of Canadian pondweed or anything sold as an "oxygenating plant". Unless you fancy spending your life dragging the bloody stuff out again. If you can avoid getting duckweed or azolla in there, that would be a good thing. If the place you buy your plants from has either of those floating around the tubs the plants are in, you can be pretty sure you'll be taking some of it home.
Substrate for the bottom - a heavy clay bottom is more natural and will provide a better habitat. If you do that, your marginal plants will gradually fill the whole thing in, unless you make it deep enough. Depends how much work you want keeping some open water. Keep in mind that the other thing about natural ponds is that they are transient, and gradually fill themselves in and go to willow and woodland. You probably don't want that to happen, so you will need some artificial maintenance.
otolith said:
... If you can avoid getting duckweed or azolla in there, that would be a good thing...
In fact if you discover the secret of how not to get duckweed then you could publish it and make a fortune 
every pond I have ever built (5 or 6 now, I've lost count) has somehow got the stuff. I believe it comes in on the feet of birds who have been drinking and washing in other ponds. And of course living near the Thames I do occasionally get ducks on mine! 
Another vote for "deeper is better".
If there will ever be children in the garden, give some thought now to making a border/edging (can be buried/concealed) that will eventually support a security mesh of some sort. Or there are grids you can fit that sit under the water's surface - much easier to install before planting up!
If there will ever be children in the garden, give some thought now to making a border/edging (can be buried/concealed) that will eventually support a security mesh of some sort. Or there are grids you can fit that sit under the water's surface - much easier to install before planting up!
A couple of rudd will control duckweed in a small pond, I've got it, but it only survives sparsely in a few corners where they can't get at it, the bulk is clear. But don't add more than a few else they will breed like mad (still a risk with just 2 obviously, but odds and a preference for shoal spawning seems to stop them). Goldfish will eat a bit of duckweed, but they won't keep going until there is none left like rudd. Other larger carp varieties are more herbivorous, some almost exclusively, but not practical in a small wildlife pond. A few rudd/goldfish fish will also keep the mosquitoes down and will not significantly harm the wildlife function of the pond.
Mr GrimNasty said:
A couple of rudd will control duckweed in a small pond.
Interesting because I've always had golden orfe because I like them, part of the rudd/roach family I believe but half a dozen of them have never made a dent in the duck weed and the y don't breed either but maybe it's not cold enough. RichB said:
Mr GrimNasty said:
A couple of rudd will control duckweed in a small pond.
Interesting because I've always had golden orfe because I like them, part of the rudd/roach family I believe but half a dozen of them have never made a dent in the duck weed and the y don't breed either but maybe it's not cold enough. Rudd are 'meat' eaters, but hey have a strong vegetarian preference.
Orfe are predominately voracious carnivores, to the extent they will leap out the water to catch insects/small animals, mine used to occasionally die biting off more than they can chew in the form of large adult newts which got jammed in their gullets by the shoulder bones. I stopped keeping them because the local foxes became expert at leaping into the pond to catch them.
I've started!
So far I've excavated most of it down to about 12", except for the right-hand end which is only 8". There will be a deep bit in the middle, down to about 30" if possible.
Annoyingly, this picture fails to show the depth I've dug down to...
For the shallow section, I plan to have 2" or 3" of soil substrate, and the water will be a couple of inches over that. There will be a retaining ridge (still below water) to keep the soil from spreading to the rest of the pond. I might try to bank it up towards an edge. My aim is to grow bog plants in this area.
Should I use special aquatic soil, or will my garden soil do?
I'm quite tempted to keep a few sticklebacks in there, but I'll definitely wait until the pond is at least a couple of months old.
Edited to add: I feel very lucky that my topsoil goes down nice and deep. There's no sign of any change to poorer subsoil yet. I've redistributed the topsoil to beds around the garden.
Edited again: As expected, I've encountered a lot of rotting willow roots, but they've been soft enough not to offer much resistance. Any large chunks of rotting wood I've stacked up in a corner of the garden, and carefully moved lots of stag beetle larvae as I've found them. Hopefully I'll have a new stag beetle nursery!
So far I've excavated most of it down to about 12", except for the right-hand end which is only 8". There will be a deep bit in the middle, down to about 30" if possible.
Annoyingly, this picture fails to show the depth I've dug down to...
For the shallow section, I plan to have 2" or 3" of soil substrate, and the water will be a couple of inches over that. There will be a retaining ridge (still below water) to keep the soil from spreading to the rest of the pond. I might try to bank it up towards an edge. My aim is to grow bog plants in this area.
Should I use special aquatic soil, or will my garden soil do?
I'm quite tempted to keep a few sticklebacks in there, but I'll definitely wait until the pond is at least a couple of months old.
Edited to add: I feel very lucky that my topsoil goes down nice and deep. There's no sign of any change to poorer subsoil yet. I've redistributed the topsoil to beds around the garden.
Edited again: As expected, I've encountered a lot of rotting willow roots, but they've been soft enough not to offer much resistance. Any large chunks of rotting wood I've stacked up in a corner of the garden, and carefully moved lots of stag beetle larvae as I've found them. Hopefully I'll have a new stag beetle nursery!
Edited by Dr Mike Oxgreen on Saturday 5th July 17:33
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