About 7 years ago I started developing various water features, both garden ponds and water falls. As part of my research I found consistent comments like the following: you can’t make a natural pond using a pond liner without pumps and filters. The use of the word ‘natural’ here refers to the pond filtration system, not the esthetic look of the pond. I’ll deal with esthetics in a future post on how to build ponds.
In a natural pond the water, soil, plants, and animals all live in harmony. No one comes along to clean the pond or to aerate it. There is no big man-made filtration system that keeps the water clean. The common advice is that a pond liner is artificial and a pond built with it will never reach a natural state where the water, plants, and animals live in harmony the way they do in a natural pond. If you don’t filter such an unnatural pond it will become full of algae and the water will be dirty and smelly. The only way to have a pond with a liner is to add aeration and filtration.
Is this really true? Do you need pumps and filters to provide artificial pond filtration?
Building Natural Ponds
This blog post is the second most popular post ever on this site. Lots of people comment and are interested in more information about building natural ponds, so I have started a public Facebook Group to make it easier for people to discuss this hot topic. Please join the group at https://www.facebook.com/groups/1760349757565562/
What Happens in a Natural Pond?
In a natural pond animals (insects, fish, etc) eat, poop, sleep and die. Both the poop and dead animals add nutrients to the water. Some is added immediately, and some is added over time as the material is degraded by various micro-organisms.
Plants also add nutrients when they die. In fall all kinds of leaves and other dead plant material is blown into the pond, and as this material is decomposed by micro-organisms it also increases the nutrient level.
Algae is a plant that grows best with high light and high nutrient levels. When the nutrients get high enough, the algae takes over the pond and chokes everything else out.
Why does the algae not take over natural ponds? The answer is higher order pond plants (not including algae). Plants also use nutrients and as long as the plants in the pond use up the nutrients as fast as they are produced, algae has trouble getting a foot hold.
The secret to an algae fee pond is to control nutrient levels!
The other important part of a natural pond is the presence of micro-organisms. They are everywhere; in the soil, on rocks, and attached to plants. Think of these micro-organisms as the ‘cleaning machine’ of the pond. They take rotting, smelly animal and plant material and turn it into nutrients that plants and algae can use. The micro-organisms keep the water clean, and keep it from smelling.
A man-made pond made with a pond liner has no soil – so one source of micro-organisms is missing, especially if you keep cleaning the pond liner. Most ponds have few stones and few plants reducing the number of micro-organisms even further. Without microbes or filtration, the dead animals and plants just sit in the bottom, making the water cloudy and smelly. But it does not have to be this way – read on.
Controlling Nutrient Levels
There are a number of ways to control nutrient levels:
1) Don’t add too many fish. Too many fish results in too much fish poop. Koi poop more than gold fish.
2) Don’t feed fish. There are lots of natural things for the fish to eat. Adding extra food just adds more nutrients to the pond.
3) Have lots of living plants in the pond. With enough pond plants growing, they will remove the nutrients before the algae can grow.
Most man-made ponds are not designed to hold a lot of pond plants. Without the plants you need to add some type of mechanical filtration system.
The picture shows a pond at Aspen Grove Gardens during installation. The black pond liner is in the deep part and the planting shelves are covered in carpet (white/gray areas). The liner will be pulled up to cover the carpet.
Note the extensive size of the planting shelves compared to the total size of the pond.
Why Aerate a Water Feature?
A natural pond has no obvious aeration. There is no hidden pump creating air bubbles. So why is it needed in a man-made pond?
A poorly designed man-made pond does not have enough plants, and it does not have enough places for micro-organisms to live. As a result, dead stuff accumulates on the bottom. As this dead stuff starts to rot it uses up oxygen, and the water at the bottom becomes depleted in oxygen, which in turn causes anaerobic bacterial to grow. This type of bacterial loves the smelly mess and they thrive with low levels of oxygen. This seems like a good thing, and environmentally it is a good thing. The problem for us is that as they digest the rotting stuff, they make the water smell. We don’t like smelly ponds even if they are natural.
How do you get rid of the anaerobic bacteria? Simple, increase the level of oxygen by pumping air into the water.
Aeration is recommended for ponds so that they don’t smell and that works quite well. The problem is that without anaerobic bacteria, the sludge on the bottom degrades very slowly and so you also need to clean the bottom of the pond on a regular basis.
Think about this. Because you bought a pump and you aerate the water, you now need to do more work and clean the bottom.
Do Natural Ponds have Smelly Sludge at the Bottom?
Sure they do. It is quite normal to find this in a pond where a lot of animal or plant material falls into the water. You don’t normally smell it because the water is not stirred up enough to move the smells to the surface. Dig around with a shovel or step into it from a canoe and you’ll find the smell. The smelly sludge on the bottom is natural.
My man-made water features have sludge and anaerobic bacteria in the bottom. If I don’t disturb them, they degrade dead plant material, and produce nutrients for growing plants. In my ponds I don’t stir up the water so I don’t smell them.
Pond Filters
Virtually every reference on building water features recommends some type of filtration system for a man-made pond. Why is this necessary?
As mentioned above, the lack of soil in the bottom of the pond and the lack of rocks and plants results in an environment that houses few micro-organisms when compared to a natural pond. The solution is to provide a man-made place for the microbes to live. Most filtration systems contain some type of surface for the micro-organisms to live on. This can be sand, wool, small pieces of plastic – it doesn’t really mater. What is important is that there is a lot of surface area. Microbes like to attach themselves to a surface and then ‘eat’ plant and animal bits as they float by in the water. So the filter replaces the natural places were microbes live–on soil, rocks and plants.
In nature the microbes live in the slime you find on rocks. It is healthy for a pond.
Water Feature Myth
The above information should give you some background to understand both natural and man-made ponds. If you think about it for a while you will realize that a properly designed pond, with enough pond plants and homes for microbes, should work just as well as a natural pond. When I was planning to build my ponds I spent a lot of time trying to find a reference for a man-made pond that worked without pumps and filters – I found none. Every reference I found said that such a pond will not work.
I set out to prove the experts wrong.
The following is not the result of good research or the opinions of experts. It is the result of my experience with two ponds over a 6 year period. In this blog I am not describing how to make a pond but I will do that in another blog entry–some day. I will provide the key points to consider.
Based on the information above, a pond design needs two things which are lacking in most designs. It needs lots of pond plants. Plants will use up the excess nutrients and keep the algae in control. It also needs lots of little homes for microorganism – they will help keep the water clean.
The following are some key design decisions:
1) Wide planting shelves. My pond is 20 x 30 feet and about half of that area is in the form of planting shelves that are about 8 inches deep.
2) Soil is not used for the plants. Pond plants don’t need a substrate, except to hold them down, and the pond certainly does not need more nutrients from soil. The plants should be using the nutrients produced by the micro-organisms and not the nutrients in soil . Instead of soil, I use small rocks – 1/2 inch or so. I just use all the small rocks I collect as I make new flower beds. Don’t fertilize your plants.
3) Pond plants are not in pots. I just place them on the small rocks in the planting shelf. A larger rock on top holds them in place until they root.
4) The sides of the pond are lined with rocks adding more surface area for microbes.
5) A deep planting shelf (about 2 ft deep) is also present for waterlilies. It is important to cover 2/3 of the surface water to reduce light getting to algae.
6) Goldfish were added to feed the plants, and eat mosquito larvae . They are never fed. They grow quickly and breed regularly.
The garden pond in the pictures was built 5 years ago and it is only now that the planting shelves are starting to be full of plants. Wild bull rushes seeded themselves the second year. Irises have been added and are spreading. The pond has never been drained, and the bottom is never cleaned. It has no pump and no filter. Wind is the only thing that might provide some aeration as it ripples across the surface of the water. There are several large trees around the pond that add fall leaf drop – which is left to settle in the pond.
For the first 4 years the pond plants increased in number each year. During this time, I did have string algae, but it mostly had a spring bloom and by mid summer it was under control. The water was very green showing the presence of lots of one celled algae, but the water was clean, and it did not smell. The fish that were added the first year did not over winter but since year two they have overwintered and keep breeding. Herons and racoons help to keep numbers in check.
From a naturists point of view the pond is very healthy with lots of frogs and dragon flies breeding each year. Larger mammals, including deer use it as a water source.
It is now nearing the end of summer 2013 and the pond has been extremely clean–much clearer than the picture below from 2012. In fact it is too clean. You can now see the pond liner in the deeper sections of the pond. There was no string algae this year and almost no one celled algae. It has been a strange year weather wise which may account for some of this, but I think it is mostly due to the fact that the planting shelves are now very full of hungry plants which are out-competing the algae.
After 5 years I conclude that aeration and filtration are ‘probably’ not required. I’ll need to wait another 5 years or so to be absolutely certain of this. It is possible that in a few more years the stuff at the bottom will overwhelm the pond and may need to be removed. I doubt it!
String algae is gone, but one celled algae is still making the water green in late summer. Note the number of plants in the water.
As plants grow and get larger, algae is almost non-existant.
Is Green Water Bad?
From an environmental point of view there is nothing wrong with water that contains algae. In a natural pond it might indicate that too much fertilizer has leached into the pond which is not good. But this is not usually a problem in a man-made garden pond. If your pond water is green with algae it is probably healthy.
You might not like the look – that is a different matter.
In Japan, garden ponds are treasured and it is common to buy a dye to color the pond water. Why do they do that? When the water is colored it reflects light much better. The shadows and reflections are considered to be very desirable. So next time someone comments about your green water, just tell them that you do it on purpose to better enjoy the reflections.
If You Have Questions
If you have further questions about building natural ponds or about your existing pond please post them in our new face book group called Building Natural Ponds.
Beneficial Pond Bacteria
natural ponds do not need to have bacteria added. For more on this topic have a look at Beneficial Pond Bacteria – A Waste of Money.
Related Posts
Winterizing Ponds and Water Features
Great article. I was just arguing with the old man about pond filtration – turns out he could be right.
We had a kidney shaped pond about 10 x 5ft (thin point of kidney) x 2ft (average depth). with a waterfall and little fountain feature. The only “traditional” filter media was the sponges on the small pump intakes. we had one reed sort of plant that overgrew the plastic bowl and eventually the reed and plants from outside the pond grew through the liner and basically that was the end of the pond. It was full of algae up to its new water level and the reed had grown roots through the bottom 6 inches of the pond.
A couple days ago while my father is in town, I convinced him to help me rip out the reed and now I’m contouring the bottom of the pond again. We’ve decided to redo the base with cement to help safeguard against incoming roots. We’re keeping both the fountain and waterfall and we are discussing at the moment whether or not we need some sort of proper filtration.
I’m hoping to heavily plant this pond and I’ve been planning to create three boxed out sections. I’ve decided to try and grow some aquarium plants in my outdoor pond. – hygrophila, Cabomba and some assorted crypts and swords. the planter boxes will take up about 80% of the pond but it will take a while for it all to grow in. I’m half expecting the crypts and hygo to just die off. the cabomba is hardy as and will probably take over if I dont prune it – assuming it survives winter. – They are “tropical” plants.
I think it’s safe to assume algae will be a problem for at least the first few months. the pond gets lots of light and being summer it’s more intense. I have two goldfish that I rescued from the old pond/swamp that will have to go back in and I’ll probably have to feed them at least a little for the first few days.
after the ponds established a little better I will add a dozen guppies and hope they breed like mad and in turn feed the goldfish too
I guess Im wondering if;
A) im doing something wrong
B) If having a pump intake at the bottom of the pond is a bad thing, and
C) will a heavily planted pond cope with a hundred guppies without proper filtration? (they breed like crazy)
Thanks!
What kind of pond liner are you using? I used 45 mil EPDM and that stuff is strong. I would be very surprised if plant roots penetrate it. When it comes to the liner–buy the best. It is just too much work to redo a pond.
I have breed a lot of fish and grew many aquarium plants in the past. Most are tropical and I don’t see why you would add them to the pond unless you have extra. As you say most are tropical and they will die in winter. Why not get something that will survive?
I’ll tell you a bit about one of my aquariums. It was about 5 ft long. I put chicken grit in the bottom–much cheaper than aquarium gravel and just as good. I planted it heavily and added some fish. No air, no filtration. In 5 or 6 years all I did was replace some water on a weekly basis since my water was very hard and the evaporation made it even harder. Plants thrived and fish thrived and bred. It had very little light so algae was not a problem.
Algae will be a problem if you have too many fish or not enough actively growing plants. You can expect it to be a problem in the first year or two. One thing you can do is cover the surface of the water with either floating plants or even Styrofoam until things get established–or just live with the algae. algae is a sign of a healthy pond–we just don’t want to look at it.
You plan looks good.
I seriously looked at putting a pump intake at the bottom of one pond. This is very popular with people with koi because they are such messy fish. I think it works fine, but I just could not bring myself to poking a hole in the bottom of the liner. It just seems like a leak problem in the making.
Do guppies breed like crazy? I know they do in an aquarium–used to have lots. But in a pond outside, you tend to get things like frogs, and they will keep the population down. but to answer your last question, there is a balance between fish poop and plants need for nutrients. It is real hard to know when you have too much poop. It is something you just have to try. If the plants are well established and growing well, and you still have too much algae–you need to reduce the number of fish or get more plants. Find a fish friend with some large fish and they will gladly come over a couple of times a year and get the extra guppies for food.
Hi I have a square pond with straight edges about 6 ft deep and 4 ft wide can I have a natual
pond there is a tree near it and it doesn’t get full sun for very long i would love to have some wildlife use it thank you Sara
I think there are differences between ‘natural’, ‘natural looking’ and ‘containing wildlife’. A square pond with straight edges will never look natural but it can have wildlife in it. The square edges prevent you from having plants at the side of the pond except for potted ones. You can however, plant in pots on raised supports. Try adding a variety of plants to see which ones will grow in the shade you have. More plants = more wildlife.
So Awesome to find your site! There is essesntialy no information for keeping a truly natural pond. I have been keeping small non filtered, nonairiated ponds for 10+ years.by small I mean any where from 11 to 100 gallons. Every one who sees them is stunned at how clear the water is. Its really just getting the balance between bog plants, water weeds and critters.
It all started with a container pond in a large plastic planter. Fast forward 3 years. The container pond completely negelected other than infreqent additions of water just cause I was infreqently watering in that direction. It over grew with horsetail reed. The plastic was faded, full of leaves twigs etc when I finally decided to get rid of it figuring it was only a haven for mosquitoes.
When I dumped it over to reclaim some of the horsetail reed I noticed movement inthewater on the driveway. It was some generation of those little clear shrimp I had put in there 3 years earlier! I was stunned that those things had lived in a small sustainable environment with no help from me and quickly tried to save as many as I could find! I felt guilty, like I was some asteroid that destroyed their little planet ! I’m sure the rootbound horsetail reed played a big part in creating and maintaining that little world .
That little event convinced me how impotant bog plants are and how easy they make it to keep a pond. The progeny from those original shrimp are in my main pond and I have 4 other ponds full of bog plants. None with a filter and so much fun to see what has taken up residence.
Thanks for posting your story. Ain’t nature grand?
We had a small 4x4x3 ft pond in our old house and we figured out how to use a pond master basic filter along w a barrel w some cylindrical things in there. We now live in a new house and 1 mo ago we had a landscaper build us a beautiful natural pond w river rocks lining the bottom and 2 waterfalls. It’s about 7 ft x 6ft x 3 ft deep. He gave us algicide to put in every 2 weeks. There seems to only be a skimmer and under it a white porous material, doesn’t seem to be much of a filter. 1 mo into it the water is GREEN GREEN GREEN and murky and we can’t even see the fish OR the beautiful stones that lined the entire pond. The landscaper keeps saying its bc I’m feeding the fish or bc I don’t have enough plants. But I think we need at least some kind of filter don’t we? There are some type of filter behind the waterfall but nothing he told us to clean. I have asked for a filter and asked for a uv light and he says I need to trust him, the pond will equilibrate. (Your article is giving me some confidence in his advice!!)
But how will it get clearer if it’s full of algae and it’s hot and sunny and nastier day by day w/o any filtration. The white sponge thing he said to clean once a year. He said he offers a pond cleaning service for $500. I had to use his pump to drain the pond for a party and clear the water prior to the party and a day later it was nasty and murky again, he said the algae came back bc I didn’t drain it enough.
So how long will it take for the water to get clear again. Right now we can’t see even the shallowest stones 6 in deep anymore or the fish. I plan to get more plants next year but seems like a lot of $$ to get them only for a few more months. Advice? Should I trust it will all equilibrate? How long will it take. The neighbors loved the pond when it was new and I’m embarrassed to show it now bc it’s so murky!
There is no need to feed the fish–they will find food including algae. Fish food leads to fish poop which leads to more nutrients in the system which leads to more algae.
The plants you want are permanent plants–perennials. It sounds like you don’t have any now and even once you get them it will take them time to establish themselves. The bigger they get, the more nutrients they will use. With my pond, the amount of algae gets less each year.
It is also natural to see an algae bloom each spring. As soon as things get a bit warm, algae will start to grow. The plants are a bit slower to get going but once they do they take the excess nutrients away from the algae and they die off–or at least get reduced in number.
For natural control the plants should be taking up half of the area of the pond, and water lilies need to cover 2/3 of the surface to keep sun out.
Algae grows very quickly, but if it is completely murking in a day, the water has too many nutrients. don’t feed the fish.
Thanks. This is very helpful. In our other pond there was shade on all sides so this open pond is new. I didn’t realize I needed that many plants. It seems expensive to invest in plants so late in the year but I plan to do so next year, though I guess I will buy some perennials now.
The water did clear up after adding algicide two weeks in a row and the cooler, cloudier weather. Our pond is about 1000 gallons and has 6 comet fish and 4 small goldfish. That doesn’t seem like too much does it? It’s so fun to feed them and they are already trained to come as soon as they see me but I will try to minimize feedings. We used to feed our other fish 2x a day in our old pond so this is a new thing for us.
I will look at your website for the right plants to get. Right now we have hyacinths and water lettuce but they only cover 10% of the pond, if that. Thanks so much for the great advice.
A real pond, even one dug by a human should require nothing. Only a fresh water source like rain, a spring or ground water. The problem is people only make money by selling you things you don’t need. Nature will always be better then man-made BS. Plus, humans like to do things that are unnatural – and that’s were things get screwed up. As an example aquiculture. Not natural, and requires on-going inputs. Here’s what I would recommend. Live small, make enough money to pay bills, live locally, eat locally, and think globally. Be happy.
Will adding a red ear turtle to a pond make it harder to maintain? Found a kidney shape pond liner at a landfill in great condition, previous owner said he had purchased it but never used it. So I brought it home immediately. I live in Anaheim Ca. And I’ve been doing some research on red ear turtles. This pond will not be buried but will be above ground. I plan on buying those nice designed bricks to camouflage the outer part of the liner. I’m glad I found this article because I do not want to run any electrical lines to the spot I’m going to keep it (plus I’m a renter). I would like to just have it as simple as possible so my 4 yr old boy can enjoy it as he enjoys the two other tortoises walking around the back yard. What plants are recommended for a small size liner as mine and how many? Thanks so much.
You don’t say how big the pond is or how big the turtle is. Those are important numbers. Turtles poop and that pollutes the water. Put a big one in a small pond and it is difficult to keep clean. Put it in a larger pond and it is much less of a problem.
Animal waste or even plant waste degrades over time adding nutrients to the water. As nutrients build up, algae will start to grow–especially when there is a lot of light present. This creates a slimy pond and some people don’t like that. The slime is actually healthy for the pond, but esthetically not pleasing. The best way to keep algae down is to add lots of plants. Waterlilies cover the surface keeping light out, and any plant with roots will use nutrients to grow. If plants remove all the nutrients, algae stops growing. You can’t have too many plants. For plant selection I would talk to some one local. I live in Ontario, and our climate is much different.
Jimmie Pitt says:
I am about to complete my third pond. I have improve my design and filtritation systems over the years. On my present pond. I am combining mechanical and natural filtration because of my narrow sloped yard. The upper pond will be the bog/marsh pond and will cascade into the lower deeper pond. Each pond is 8×8 ft. The lower pond is 3ft. deep and has planting shelves on two sides. The upper pond which will be the marsh will contain 2 ft of gravel and lots of plants.
Water lilies went in lower pond yesterday, I will plant the marsh pond as my work schedule permits. I will give updates as work progresses.
Sounds like a good design. I was going to put a filtering pond at the head of my waterfall. Originally I like the design where the water enters the upper pond at the bottom and perculates up through the sand. After a lot of reading I decided that such a system clogs to easily, and once that happens it is difficult to unclog. In the end I decided not to use one.
Thank you so much for the information. My husband and I want to build a pond in a natural low part in our yard. My little confusion is this…I don’t know how deep we will go. What about a shallow pond…say 5 ft..will water plants and fish do alright in this depth?
5 feet is not shallow. Most man made ponds are 2-3 feet deep. My large one is 4 feet deep.
Plants like depths of 6 inches to 3 feet. Things like Iris and bull rushes like it shallow. Small waterlilies are happy at 2 feet, and larger ones at 3 feet.
Ponds don’t freeze very deep. Once the surface is covered with ice, the heat from the earth keeps the rest of the water from freezing. Fish usually die from lack of oxygen. Dead plant material in the bottom decomposes and gives of CO2. When the surface is open this co2 can escape, but once the pond is covered with ice, it can’t. As it builds up, the fish die. Gold fish in my 4 foot deep pond had no problem surviving for several years. Last year it got cold early and stayed cold for several months. This meant the pond was covered with ice for a long time. The fish died. A simple solution which I will try next winter is to have a simple air pump going all winter. Even a small hole will allow the CO2 out.
For gold fish in zone 5, I would aim for a depth of at least 3 feet. Warmer climates need less.
Robert
Our pond is approximately 9X11 and 3 ft. deep In center. It has been established for 10 years. We have a waterfall and stream with a pump and skimmer setup. I really want to make it natural and not run the pump. I read your articles several times and took your advice. I have downsized on number of fish, put in more plants and I am trying to get more top coverage. I have also stopped feeding the fish. Our pond gets a great deal of sun. We did drain the pond this spring and clean it, and I put some chemicals in it to keep algae down because I am afraid to shut the pump off till I know the fish will be safe with enough top coverage to keep the water cool enough for them. I really would like your input to see if I am on the right track. I also put a couple small grass carp in to help keep things clean.
Cleaning the pond removes the important bacteria – don’t clean the pond.
Don’t add chemicals. If algae grows let it grow. How else will you know you have an algae problem?
We have lost 3 fish in about a week. They died for no apparent reason. Never had this happen before. Our water looks good. I did have it checked though. The PH was hi. The gal at the pet store stated that when the temps are extremely hot it takes oxygen out of the pond. She suggested taking the pond down a 1/4 and refilling. What do you think about this.
Warm water holds less oxygen – that is true. Replacing 1/4 of the water won’t change this.
If the pH is high, the next question is why? What is the pH of the water being added? If the water being added has a lower pH, replacing some of the water will reduce the pH. If the replacement water is also high – which I suspect – replacing water will not change anything.
Adding rain water will help. The pH of rain water is acidic – usually around pH 5.2.
If your tap water is hard, the pond pH will go up slightly over time as water evaporates. In this case a change of 1/4 might help.
We just lost another fish yesterday. We have had so much rain here I dot know how we could have a high PH. I only did this 1/4 water change. Last week. What is odd we have now spotted baby fish approx. 1 inch in size. We figured they would have all died like the big ones. Just received 4 inches of rain the other day. I am really frustrated. Have talked to a number of other people and they have not lost any fish. I have about 2/3rds of the pond covered with a sheet of insulation suspended above the pond. Lots of plants also.
Have you tried taking a live fish out and looking at it. Can you see and disease?
I just remembered that a while back when we were fishing a lake we pulled some plants from the lake that are Arrow Arum I believe. We brought them home and I put them in a bucket of water to wash all the mud off. Then I set them on the pond shelf and weighted them down with a rock. Is it possible that something from them has killed our fish?
That is certainly possible.
Mr Pavlis
We ended up loosing all our Koi. I took a water sample to our DNR outlet. They concluded it was due to my adding 3 pieces of old dead tree limb pieces. It was for cover for the fish to get under and in. We were told that the wood continued to rot and decay in the water and give off bacteria and take oxygen out of the water. We didn’t suspect that since it had been in there for 2 years.
My husband wants to know if we could just put a small bass or two, catfish and probably a couple small grass carp? Will they sustain in our pond with out their natural food source supplied by a lake. Referring to them being predator fish(bass,catfish). Do you have any advice for us?
Thank you
I don’t believe the wood caused the problem.
check the amount of space required by the fish as well as their preferred temperature. Provided you provide what they need to live and grow they should be fine.
I love your post and cant wait to try your method. Keep the information coming. Your logical approach to sustainability and self sufficiency is refreshing.
Thank you very much.
We have had a succession of small backyard ponds for 43 years, none with filtration, so I found your new posting really interesting.
Our most successful approach has evolved to keep the vegetation, especially the water lily blooms, out of the reach of hordes of city raccoons. In the most recent design, the flowers still get nipped, but the fish are happier and the pool requires far less maintenance. We clean the debris from the bottom once each year in the spring but no longer remove the algae from any surfaces.
We have eliminated planting shelves because the raccoons simply tore out everything at the edge. The really shallow plants, acorus and irises, are wired in their pots to uprighted cement blocks. The cement blocks function as obstructions to prevent the raccoons from dragging the pots of water lilies by their leaves to the edge of the pond. The holes in the blocks have become havens for the fish when the raccoons take laps around the pool (really!!!). Now, reading your posting, I realize that the blocks are significantly increasing surface areas and we can try wiring the rhizomes directly to the blocks without pots.
We still have too many fish since baby goldfish are as hard to give away as kittens. (The fish store no longer will accept them as shark food to avoid introducing disease from outdoor ponds.) Fortunately we have a friend whose setup is not favourable to overwintering his fish, so he’ll take 2 or 3 12” adults off our hands each year. Successful reproduction is limited by the large number of adults which eat the eggs, so just enough babies survive to replace the ones we give away.
As for not feeding the fish, that may be difficult. My 99 year-old mother-in-law and all of the neighbourhood kids clamour to get their turns feeding them. The fish were introduced to keep down mosquitoes, but now they are pets and are a real attraction.