What Filters Do I Need?

[Lisak1]

Well I won't argue with the computer model. But I will say all those plant shelves are going to be useless - the stepped down area I mean. Pond plants fall into three categories - floaters, marginals, and submerged. The floaters, well, float. The marginals grow in the shallow areas around the edges of your pond - most want their crown near or even above the surface of the water. Submerged plants can be either oxygenaters or water lilies. Oxygenaters generally float freely. Lilies are potted and can be placed anywhere from 12" to 4 feet under water. So your multiple shelves are really only useful for lilies and you won't want that many pots that close together - lilies spread in a circle 3-5 feet or more on the surface. Crowding more of them in a small area would serve no real purpose.

Plants in pots take up space. While they do provide shelter and shade, they also reduce the room your fish will have to swim. And yes, the deepest part of your pond is small. Koi need to swim both side to side and up and down. Your design will allow a very small area for your fish - I would suggest rethinking that.

As for overloading a pond - as I said before you can definitely do it. You will just need to be devoted to your filtration and water quality. And the poster with 2000 koi fry specifically said he had removed the fry from his pond. As you said, koi definitely do NOT limit their growth to the size of their pond - that's an old wives tale. Keeping that many fish would require a lake, not a pond.

And yes, water quality is critical in an intentionally overstocked pond. But overcrowding can also lead to stress which is also harmful to fish. And in too small of a space a koi can even become malformed. We saw a 30 inch koi in a 30 gallon aquarium once in a car repair shop - it's tail had formed a permanent hook to accommodate the tight quarters. But they had it proudly displayed with a sign saying he fish had lived in that tank for 19 years. So sad to see. Also an extreme example to illustrate that water quality is only one consideration.

 

[Mucky_Waters]

I brought up the yard ornament example earlier only as an example to illustrate that volume restriction, no matter how extreme, must be far less important than water quality. I have read that pond volume is a limiting factor in how big a koi can get. Clearly that is not the whole story.

Humane examples of relatively small volumes in proportion to their fish populations can be found on this forum, like the guy with 2000 'baby' koi and this guy who pumps 4,300 gph through his 435 gallon pond. They both have massive filtration systems to maintain good water quality.

One thing that does concern me is that at the deepest part my pond is not very big. I don't know if koi need a lot of room to swim around at that depth, or if they just need it as a place to hide or rest. I hope that by having lots of plants, the fish will feel less constrained by the size of my pond. In regards to total volume, does this in any way limit how big a koi can get?

It's true that you can stock a lot more small fish than big fish. However, those little fish can grow quite rapidly, especially koi. And don't count on that pond volume thing limiting their size. The amount and quality of food you give them is a bigger factor to how big they grow then the pond volume.
That being said, by most standards my pond is overstocked, or will be if all my fish, frogs and turtles grow to full size. I have a 2,000-gallon pond, about 18 goldfish (3" to 7") , 3 koi (6" to 10"), about 20 minnows (1/2" to 3"), 2 frogs and one turtle (not full grown, but getting bigger every year). I've given away a lot of the minnows and smaller goldfish, but they keep producing new ones every year, especially the minnows, despite the best efforts of my turtle to keep them in check and fill his dietary needs.
The best advice I could give you, and I'm sure everyone will agree, is to try and make your pond bigger and deeper, that will give you the extra capacity to squeeze those extra critters in there or accommodate fewer better . And regarding all those shelves in your CAD pond design, it will be very hard to get a liner to conform to the shape. A simpler open design with fewer corners and shelves will allow your liner to lay flatter and produce fewer wrinkles and probably give you more water volume.
Oh and you mentioned possibly a turtle? Turtles will wander off if you don't fence them in somehow, especially if they sense that the pond is too small, and no turtle in nature would stick around in a natural pond anything less than 10,000 gallons.

To see where I'm coming from this is my pond build.

And a not so recent video showing more what it looks like now.

 

[MitchM]

sburtchin, how thick does your ice typically get during the winter?

 

[sburtchin]

But I will say all those plant shelves are going to be useless - the stepped down area I mean.

I think you are talking about the ones that look like stairs. I have limited experience with pond plants, so I only have some books that I read with a grain of salt and my not necessarily accurate recollection of what I read on tags at the nursery. I was thinking that by creating shelves at many different depths, I would be prepared for anything. The downside was that I didn't end up with much space at the bottom.

A note of clarification on the shelf that goes around the perimeter of the pond. The interior of the pond will be all stone mortered in place. The shelves will have pockets for some standard sized pots to fit into so that the plant crown will be flush with the top of the plant shelf. That shelf varies in depth from 6" to 13". Is that a good range for all marginal plants?

If I eliminate the three intermediate steps at the narrow end and the one intermediate step in each lobe at the wider end, the area at the bottom would be about 7' 4" long x 2' 2" wide at narrow end and about 3' 6" wide at other end, with a little extra room in the two lobes. Those plant shelves are about 13" wide, not counting the slope of the vertical walls. Pockets in the bottom too, so no swimming space taken up by plant pots, only the plants themselves. Is that still too small at the bottom?

We saw a 30 inch koi in a 30 gallon aquarium once in a car repair shop - it's tail had formed a permanent hook to accommodate the tight quarters. But they had it proudly displayed with a sign saying he fish had lived in that tank for 19 years. So sad to see.

OK, you win. I can't top that for cruelty to a koi. At least the fish in the yard ornament had each other for comfort. What is it with these small businesses using exotic animals kept in horrific conditions to attract customers. Reminds me of the souvenir shops with the bear chained out front with all its teeth and claws removed.

 

[Meyer Jordan]

That shelf varies in depth from 6" to 13". Is that a good range for all marginal plants?

Different emergent aquatic plant species have different depth requirements. Some will tolerate 12" (or more) in water depth over the crown of the plant while others will tolerate only maybe 1". Most online aquatic plant nurseries will list the depth requirements for each plant.

 

[sburtchin]

And regarding all those shelves in your CAD pond design, it will be very hard to get a liner to conform to the shape. A simpler open design with fewer corners and shelves will allow your liner to lay flatter and produce fewer wrinkles and probably give you more water volume.

Stripping away everything but the dirt and the concrete support rim, the shape for the liner to conform to is far less convoluted, especially if I eliminate all of the intermediate depth shelves.

This next image shows how the liner drapes over the support rim. It can be fastened to the outside of the rim to keep it in place.

The best advice I could give you, and I'm sure everyone will agree, is to try and make your pond bigger and deeper, that will give you the extra capacity to squeeze those extra critters in there

That's where it gets difficult because my yard is pretty full, but still looking into that.

Oh and you mentioned possibly a turtle? Turtles will wander off if you don't fence them in somehow,

I will need a taller fence anyway to keep out the neighbor dogs. Possibly electric so my fish can swim upstream without fear from the raccoons and opossums. Then a short solid fence to keep in the turtles.

To see where I'm coming from this is my pond build.

Are those small square pavers you used for the pond sides? If I'm seeing this right, you have the layer of pavers inside the liner, then a layer of mortar to hide the pavers? Does your turtle leave all the larger fish alone? What about the frogs?

sburtchin, how thick does your ice typically get during the winter?

I don't think it has ever gotten more than 6" in my 50 gal pond with the water flowing. In a calm water environment I suspect it could get much thicker. The frost line here for construction purposes is 30", though the ground rarely ever freezes to that depth. Smart builders here set their footers at 36". I move all my plants to deeper water for the winter except the irises. The water freezes solid around them, and only the leaves are damaged.

 

[MitchM]

I don't think it has ever gotten more than 6" in my 50 gal pond with the water flowing. In a calm water environment I suspect it could get much thicker. The frost line here for construction purposes is 30", though the ground rarely ever freezes to that depth. Smart builders here set their footers at 36". I move all my plants to deeper water for the winter except the irises. The water freezes solid around them, and only the leaves are damaged.

I asked about your ice because there is someone else that has a small single deep area for his koi to retreat to during the winter and he seems to have fish deaths every year.
Your pond design looks like it could have the same issue, if you winter your koi outdoors.

.

 

[Mucky_Waters]

That's where it gets difficult because my yard is pretty full, but still looking into that.

Are those small square pavers you used for the pond sides? If I'm seeing this right, you have the layer of pavers inside the liner, then a layer of mortar to hide the pavers? Does your turtle leave all the larger fish alone? What about the frogs?

The soil that I had to work with was very loose and rocky, I wanted a deep area with vertical drop sides, so I used what I had to build up the sides which happen to be a bunch of extra homemade pavers, so yes, you are seeing correctly.
And yes the turtle leaves the larger fish alone, for the most part, but the larger koi and some of the other fish often try to steal food out of the mouth of the turtle. When that happens I have seen the turtle retaliate and nip back at the koi, consequently one of the whiskers of the koi is shorter then the other. I don't blame the turtle at all, if someone was constantly trying to steal my food I'm sure I'd do the same thing.
In order to ensure that the turtle gets enough food we try to feed him by hand most of the time.

 

[lillysbaba]

My humble two cents worth here; First, installing a liner with that many shelves and elevation changes will be an enormous challenge. We struggled with two shelves in our rectangular pond. Wherever there is a fold to accommodate the shelves there will be a place for debris to accumulate. I vacuum these areas at least three times a year and cannot get over the amount of debris that collects.
Second, it has been my experience that Koi think that water lilies are a salad bar. I will never forget putting in a pot of floating heart into the pond. I went to find my husband to show him how pretty it was in the water and when I came back it was completely gone! I have also had them dig up the entire root of a lily, killing it of course. Over the years I have found plastic hardware cloth and wrapped it around the pot, making it just tight enough so that I can slide it up or down to accommodate the growth of the plants. Most of my koi are older than 10 years so they have finally figured out that they can't get to the plants and are satisfied to nibble on the leaves. All was well until we had a youngster from a spawn last year who was small enough to scale the "fence" and muddied the water so bad we couldn't even see the fish. Haven't seen comments regarding this, but it has been a major battle for me. This brings me to the third thing I would like to mention:
Third: I think that the more separate systems you have the better off you are. We had endless problems keeping our skimmer from floating up (Oase freestanding skimmer) because we were splitting the intake between the skimmer and the filter. It was a real problem for a long time. We took the skimmer out for a while and it was very quickly evident that it was a mistake. I ordered a pump that would be dedicated to the skimmer and re-installed it, routing it through a Tetra bio filter. The difference in the water quality is incredible. So now we have four different pumps going and if something should malfunction we won't be scrambling around at the last minute trying to fix something essential for the well-being of the fish.
Your design is really nice and it will be a real asset to your yard. Please write updates as you do the construction; it will be an inspiration to all.

 

[sburtchin]

I asked about your ice because there is someone else that has a small single deep area for his koi to retreat to during the winter and he seems to have fish deaths every year.
Your pond design looks like it could have the same issue, if you winter your koi outdoors.

Not knowing more about his situation, I wonder if there is more at work killing his fish. I have never had large koi, so I don't know about their special needs. But speaking of small spaces to overwinter large koi, the yard ornament example I mentioned is run 365 days a year. There is no heater and the water never freezes because it is flowing so fast. I don't think he has ever lost a fish. In my own experience, I have had a 50 gal hardshell pond for about 15 years. I have rarely lost fish in the winter. At first I had only goldfish, and I would turn off the pump for the winter. One unusual winter it remained ice covered for 8 straight weeks. When the ice finally melted, it smelled like a sewer and every fish had died except the largest. That fish went on to live another 7 years. Since then I keep the pump running. I had some small koi for a while. A couple years ago we had another harsh winter. With the pump running I lost all my koi and half of my goldfish. Then I read that koi can't take temperatures below 34 F for long periods. Except for these two incidents, most of my losses have been from cats, raccoons, neighbor dogs that panic when they fall in, and fish that decided to go exploring on land. As far as overwintering, I move all my plants to the small deep end (only 18" deep) and there is barely space between the pots to accommodate all the fish. For the most part I rarely see them move when the temperature is near freezing. Some larger fish would claim the prime spots and not budge all winter. If I remember right, the koi were sedentary for much longer than the goldfish.

I am more inclined to believe that swimming space is beneficial in the summer, and could play a role in achieving adequate fat reserves for the winter. In the following image, the outer white line is the profile of my pond design at 13" depth. That would be inside the shelf that goes around the perimeter of the pond. The red line represents the profile at the bottom at a depth of 44" as currently designed. If I remove the shelves at the intermediate depths, the bottom profile would be represented by the inner white line. 8-1/2" is how much the pond wall slopes inward from 13" depth to 44" depth. I hope that's enough to keep the walls from collapsing inward. My water table can be very high.

Does this provide enough deep water swimming space?

The bottom of the pond will have pockets to accept standard size plant baskets so that the crowns of the plants will be at a depth of 44" also. Is this too deep for water lilies?

 

[sburtchin]

The soil that I had to work with was very loose and rocky, I wanted a deep area with vertical drop sides, so I used what I had to build up the sides which happen to be a bunch of extra homemade pavers, so yes, you are seeing correctly.

Then your liner goes on top of the pavers? Is your liner bare or is there stone on top of it? Your turtle is little now. Does he or she try to dig holes?

Do you have a mold to make a lot of pavers in one batch? Did you make the mold yourself or buy it?

 

[sburtchin]

First, installing a liner with that many shelves and elevation changes will be an enormous challenge. We struggled with two shelves in our rectangular pond. Wherever there is a fold to accommodate the shelves there will be a place for debris to accumulate. I vacuum these areas at least three times a year and cannot get over the amount of debris that collects.

See my post #21. The multiple elevation changes in the shelf around the perimeter is accomplished with stone placed inside the liner. The liner will be completely covered on the inside with stone and mortar so all those folds are sealed. Now imagine the hole shown in post #21 with the revised bottom profile shown in post #25. Agreed, the folds in the liner with all those shelves at the intermediate depths would be pretty complicated. Without them, there is just the shelf around the perimeter - the same height (the dirt that is) all the way around.

Over the years I have found plastic hardware cloth and wrapped it around the pot, making it just tight enough so that I can slide it up or down to accommodate the growth of the plants.

Thanks for this tip! That has been a major battle for me too. I have been cutting pieces of landscape fabric to fit around the rhizomes and fitting in a mosaic of stones on top of that to hold it in place. It is tedious and time intensive. Without the fabric, the turbulence from their tail fins just erodes the soil out from under the stones. They still sometimes manage to knock the stones away and then wreak havoc. The bigger fish will knock over the plant baskets, then the stones fall out. The other big problem doing this is that the lilies grow over the fabric and push some roots through it, then it can't be separated.

Now, I want to be sure I understand how you do this. Do you make a cylinder out of the plastic cloth that slides down vertically over the pot? How high above the pot does it have to extend? Are you speaking of that plastic fence that cris-crosses in a diamond shape pattern with holes about 1/4" square? I have some of that. It is pretty stiff. I have to use tin snips to cut it. I'm not sure if the stems of the water lilies could take the abrasion from rubbing against it. Are you referring to something else?

 

[MitchM]

Not knowing more about his situation, I wonder if there is more at work killing his fish. I have never had large koi, so I don't know about their special needs. But speaking of small spaces to overwinter large koi, the yard ornament example I mentioned is run 365 days a year. There is no heater and the water never freezes because it is flowing so fast. I don't think he has ever lost a fish. In my own experience, I have had a 50 gal hardshell pond for about 15 years. I have rarely lost fish in the winter. At first I had only goldfish, and I would turn off the pump for the winter. One unusual winter it remained ice covered for 8 straight weeks. When the ice finally melted, it smelled like a sewer and every fish had died except the largest. That fish went on to live another 7 years. Since then I keep the pump running. I had some small koi for a while. A couple years ago we had another harsh winter. With the pump running I lost all my koi and half of my goldfish. Then I read that koi can't take temperatures below 34 F for long periods. Except for these two incidents, most of my losses have been from cats, raccoons, neighbor dogs that panic when they fall in, and fish that decided to go exploring on land. As far as overwintering, I move all my plants to the small deep end (only 18" deep) and there is barely space between the pots to accommodate all the fish. For the most part I rarely see them move when the temperature is near freezing. Some larger fish would claim the prime spots and not budge all winter. If I remember right, the koi were sedentary for much longer than the goldfish.

I am more inclined to believe that swimming space is beneficial in the summer, and could play a role in achieving adequate fat reserves for the winter. In the following image, the outer white line is the profile of my pond design at 13" depth. That would be inside the shelf that goes around the perimeter of the pond. The red line represents the profile at the bottom at a depth of 44" as currently designed. If I remove the shelves at the intermediate depths, the bottom profile would be represented by the inner white line. 8-1/2" is how much the pond wall slopes inward from 13" depth to 44" depth. I hope that's enough to keep the walls from collapsing inward. My water table can be very high.
View attachment 90140

Does this provide enough deep water swimming space?

The bottom of the pond will have pockets to accept standard size plant baskets so that the crowns of the plants will be at a depth of 44" also. Is this too deep for water lilies?

The claim that koi cannot live very long at 34F is not based on any fact.
I think the majority of koi and goldfish fish losses during the winter are due to insufficient oxygenation levels, not the temperature of the water.
There are many myths about the water conditions in a pond during the winter. You may find the results interesting if you have an accurate thermometer probe placed at the bottom of your pond.

 

[lillysbaba]

See my post #21. The multiple elevation changes in the shelf around the perimeter is accomplished with stone placed inside the liner. The liner will be completely covered on the inside with stone and mortar so all those folds are sealed. Now imagine the hole shown in post #21 with the revised bottom profile shown in post #25. Agreed, the folds in the liner with all those shelves at the intermediate depths would be pretty complicated. Without them, there is just the shelf around the perimeter - the same height (the dirt that is) all the way around.

Thanks for this tip! That has been a major battle for me too. I have been cutting pieces of landscape fabric to fit around the rhizomes and fitting in a mosaic of stones on top of that to hold it in place. It is tedious and time intensive. Without the fabric, the turbulence from their tail fins just erodes the soil out from under the stones. They still sometimes manage to knock the stones away and then wreak havoc. The bigger fish will knock over the plant baskets, then the stones fall out. The other big problem doing this is that the lilies grow over the fabric and push some roots through it, then it can't be separated.

Now, I want to be sure I understand how you do this. Do you make a cylinder out of the plastic cloth that slides down vertically over the pot? How high above the pot does it have to extend? Are you speaking of that plastic fence that cris-crosses in a diamond shape pattern with holes about 1/4" square? I have some of that. It is pretty stiff. I have to use tin snips to cut it. I'm not sure if the stems of the water lilies could take the abrasion from rubbing against it. Are you referring to something else?

The material I am referring to has 1/2" square holes and is stiff but pliable plastic. It is easily cut with scissors. The package I purchased was called plastic hardware cloth. It is usually in the gardening section with the shade cloth but not always easy to find. If I am near the end of a roll I buy it when I see it because it may not be there the next time. The outer edges are smooth so it is safe to use around the fish. I cut the width I need and wrap it around the pot overlapping it by a couple of inches. I then use a zip tie to attach the first two overlapping holes and then thread the remaining length of the tie through the double row of holes. Usually it takes two or three ties to accomplish this. Once the pot is placed in the water you can trim it just below the water level making sure to trim it so that the edge is smooth, or you can slide it off of the pot and flip it around so that the smooth selvage edge is on top. Make sure that the net is close to the bottom of the pot so that you have some room to move it up if you need to. It will also keep the fish from bumping the nets off ( mine did it deliberately!) The size of the fish will determine how close to the water level the top of the net needs to be. I had mine 2" below the surface because my koi have gotten very large, but now that we have three small guys from the spawn last year I have had to raise the level. It's not an issue now, but when the lilies get bigger and there are more leaves I will have to lower the nets a little. The only problem I have had with doing the pots this way is that sometimes the leaves grow through the mesh and get stuck and I have to remove them, but losing an occasional leaf is better than the plant being completely ravaged by the big guys. hope this helps.

 

[sissy]

I agree with Mitch fish do not die unless neglected over the winter .I have had my koi over 11 years and almost lost them one winter when the crate I had my pump tied to tipped over and put most of the water out of the pond .I had about a foot of water left and with a snow storm coming I had to refill the pond with hoses from the inside taps and if they can live through that they can live through any thing .Then 2 years ago over the winter moles chewed my liner and had to keep refilling until March got here to rebuild with a new liner and of course the addiction set in and i went bigger .Fought snow 3 times to get it done