I think it's a great size for a Koi pond. The depth will help them develop right. Have you visited the koi forum & asked there?

4' depth is good enough, 6' deep is even better especially where you live. 4' depth is only going to give you 1400 gallons or so, which is really very small for a koi pond. the fish will survive....but they will never achieve the growth or build that you see on large koi because the pond is too small for them to exercise properly. Koi need depth to swim up and down, but they also need to be able to swim distances. Plus the volume is really small. Even at a very heavy stocking rate of one koi per 250 gallons, you will only be able to have 5 or so koi. I prefer a stocking rate of about 1 koi per 500 gallons.

If you go with a 10' diameter pond instead of 8, you can get 2335 gallons and if you go to 12' you can get 3300 gallons. Increase the depth to 6' and you will get 2200 gallons from 8' and 3500 gallons from 10' diameter. You should also plan to put in a bottom drain that connects to the filter. That will make the environment so much healthier for the koi.

You have a good start with your plan.....just see if you can get a little more volume out of it. Trust me....more water is much easier to keep stable and healthy than less water.

Ours is about 3 1/2 feet deep and it's fine on Long Island. Eight feet round is not big enough for Koi, they love to swin and need more room. Our koi are 24-26" long. Consider doubling the length at a minimum, longer is even better... Also consider a bottom drain, it's the single most important thing you can do for your pond.
check out our DIY Pond plans and diagrams in our website.
Good Luck, Joann

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Here is a link that might be useful: Pond website.

I'm in agreement with ccombs and cliff/joann: 4' deep is pretty good but not great; 8' diameter is pretty small; total volume will not support many fish. Imagine a moderate size 24" fish swimming in an 8' pond, he'll be turning basically all the time. Many people I think would be happy with a pond that size and the koi will do reasonably well. If that is the size you have to work with then I wouldn't want to disuade you. I think you would enjoy it a lot and the fish will reward you even if they don't reach their full potential. OTOH, it doesn't cost much more to double the size and triple the volume as suggested above with twice as long and 6' deep. Of considerable benefit to the koi, maintenance and ongoing cost would be very similar. I agree that a BD would be an extremely valuable addition, I don't think that is the single most important thing you can do for your pond. I'd vote for an oversize biofilter as the single most important thing, no rocks on the bottom as a close second, and BD then brings in third place.

I agree with ccoombs but I would think the volume would end up less than 1000 gallons.
Mike

Volume of a cylinder = pi * radius squared (radius * radius) * depth.

3.14159 * 16 * 4 = 201 cubic feet.

convert cubic feet into gallons by multiplying cu feet * 7.48 and you get 1503 gallons, if the pond is filled to the top.

So you actually get more than 1400 gallons.....but it's still not large enough for koi.

my limitation is my property. Those of you on Long Island are aware of the small lots that these houses are on. I have 65x100. I understand what Koi need now, and I would never think about putting them in something that would hurt them in the long run. I know because I'm a saltwater enthusiast. I need to be cognizant about which species, fish and coral can cohabitate. So, basically what most of you are saying is that Koi prefer, a longer pond more so than a roundish one. Well, I have one of two options, either Keep the pond plans I have now and place goldfish or shubunkin in the pond, OR move it to another location where it would take up more of my property, there would be more sun, and I can have Koi. I think I have some more thinking and planning to do. Thanks for the advice all.

The bottom drain continually recycles the water from the pond through mechanical filtration and back into the pond again.
How is the same thing accomplished in a big pond without a bottom drain? Without a bottom drain how is the stuff and fish waste that accumulates on the pond bottom get out of the pond?
Vacuuming the pond a lot and emptying the pond each year is one way. With a bottom drain the pond floor is all slightly tilted towards the bottom drain and the dome designed drains continually create a swirling motion to suck all the stuff through the bottom drain and through the filter that is located outside the pond, thus trapping the waste before it re-enters the pond. Having had a pond for ten years with a DIY however very efficient filter system complete with bottom drain, I can tell you without hesitation, it is the single most important thing you can have in your pond-- everything else, such as making the pond bigger, biofilteration, skimmer, etc...can be added later.
Fortunately for us when we wee buying our pond supplies to build a pond the salseman was a seasoned pond keeper and explained in detail the premise behind the bottom drain, we don't have to empty our pond for cleaning the bottom or vacuum it. But we do have to go in occasionally and pick up all the rocks that the koi scatter on the bottom of the pond from digging in the pots and from the shelves, most of the time we use a net to scoop up the rocks, most of the time we use a net to scoop up the rocks.... For this reason, I would not recommend a 6 ft deep, it is just to difficult to get to the bottom, I rather have the volume of water in the size of the pond, 4 foot is deep enough and still manageable for maintenance.
See the small pebbles in need of picking up? There is two milk crates and a potted lily, they were digging in the lilly and scattering the rocks on the bottom.

I stand by the statement, a bottom drain is paramount in a large pond, anyone else with or without one care to chime in?

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It also aids trememdousally in keeping the pond clean, because it removes all the fish waste continually, so that you can enjoy seeing your fish through crystal clear water.

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Do you have instructions for putting in a bottom drain? Would I have to put a hole in the liner and run PVC piping underneath the underlayer and liner and run it up to the filter?

Putting in a drain is easy in a new pond. The drain is set in a bed of concrete first, so it doesn't ever shift of settle. The 4" PVC line is run in a ditch in the bottom of the pond and up to the filters. the ditch is filled in and the soil packed. then you install the underlayment and liner. Once the liner is in place, you cut a hole in the liner in the center of the drain. At this point, I make the hole only large enough to get my hand in with a tube of sealant. Apply a large bead of sealant to the drain's flange face. Stick the liner down to the flange face and then start screwing the band down, running the screws down thru the cover flange, liner, and into the drains backer flange. the screws are stainless steel and won't rust. Once the screws are all tight, you can trim the liner inside the drain hole. Insert the stem and dome cover. the stem might need to be trimmed shorter because you only want maybe a 3/8" gap between the liner and the edge of the dome cover. I have installed a total of 5 of these drains in my own ponds and never had a leak.

How many fish are in your pond Joann, including any goldfish, etc.? I see about 20 koi in the photo and they are all medium to very large looking? Your pond WOULD look very different without a BD.

I am not going to argue as to have a bottom drain or not. Had I the skills and money and know how I would have one because I believe that it is not just one thing that influences the overall health of a pond system or it's clarity for viewing. Having one is an enhancement to reduce waste and maintenance, but not having one is an option as well provided other compensations are made on the controllable factors within the perview of the pond owner and their specific situation.

Some factors one needs to think about:

Ability to maintain and afford everything, number and type of fish to be kept, water volume, plant coverage, surface area, total depth, feeding habits, types of filtration and proper filtration (which IMO should exceed recommendations of most pond book recommendations), sunlight exposure, water chemistry, biological filtration, bottom drain filtration, and so forth.

Here's another thought. If you are limited in the size of your pond then find fish that will fit.

There are beautiful goldfish that are being bred now for ponds-- some have the vivid dots and markings on top for good viewing in a pond. Some shebunkins have gorgeous sparkly blue, red, black, yellow and/or white markings. Even an ordinary red comet can look very koi- like with long flowing fins and tail. A lot of these are virtually indistinguishable from young koi - only their not having whiskers gives them away. That and they only get 12 inches and not TWO- THREE FEET LONG.

A two foot fish in an eight foot pond just sounds terribly cramped and unhealthy for the fish. You will have fewer fish so you won't get the lovely visual effect of a school of fish moving thru water--its like they travel in waves and its just very enjoyable to watch.

An alternative is to find new homes for your fish once they start to get large. Still, I wonder why the fixation on koi (not you specifically, people in general). Yeah, I know they are smart and beautiful, but if you've ever seen a pond of large full grown goldfish you'd know how much fun they can be too!

"Still, I wonder why the fixation on koi (not you specifically, people in general). Yeah, I know they are smart and beautiful, but if you've ever seen a pond of large full grown goldfish you'd know how much fun they can be too! "

I can comment on this one. If you've ever seen a pond full of really high quality, mature koi, you would understand the fixation. Or obsession. LOL! They are beautiful, powerful, elegant, and very colorful. They have amazing personalities too. I like goldies (I keep Wakins in one pond), but a even a large mature goldie can compare to seeing a herd of large koi swimming so powerfully across a pond that they actually leave a large wake behind them. Seeing large koi in a large pond is a beautiful sight. Seeing large koi swimming in small lazy circles because their home is too small for them is very, very sad.

I read in the new Ponds 2007 annual that it's better to put two bottom drains ( I guess it depends on the size of the pond) this way, if one clogs, the other one will release it's suction to allow the clog to be removed. Also, in case of a child accidentally falling in, there wont be a tremendous pull from only one drain. Did I understand this correctly?

No intention to attack you cliff/joann, far from it. Your original post implied that a BD would be a more valuable addition than any other component, seemingly including a biofilter. I just had some trouble envisioning a pond with BD and inadequate biofiltration being better than one with good biofiltration and no BD. Further, I had trouble envisioning a pond with rocks all over the bottom with a BD being better than clean bottom no BD. No argument from me, though, BD is vital. I have a bunch of BD, at least one in every pond, two aerated. No rocks in bottom. Huge biofiltration. And some other helpful tidbits.

petem....that's not true at all. two are needed if the pond size calls for it.....usually one drain will pull from a 12' radius. The drains do not pull enough to create enough currents to suck a child down! Each drain goes to it's own filter, so one drain has nothing to do with the other and will not affect the other in anyway. I can't imagine how that magazine came up with that!!

Petem, I took a shot at responding to your querry before. It didn't post, so here we go again: Many BD feed by gravity to a SC or vortex chamber, there is not enough pull that way to hold a child. Not as good for the filtration system, some BD feed directly to pump suction. In this case there could be heavy suction and the potential could exist to hold a child underwater. Two BD to the same pump would essentialy preclude any such possibility. HOWEVER, good BD draw water from a large circumference and their domes are firmly attached. A child could not plug these BD and therefore could not be caught by the suction even if only one were present (never say never, I suppose, but I think lightening would be a much greater risk). HOWEVER, cheap BD (the one I'm thinking of is the 3" Tetra) do not have firmly attached domes. If a child were to dislodge the dome there would exist a 3" hole with potentially formidable suction. In that case I would not be surprised if a child might potentially become trapped. I see little risk in any application except the direct suction cheap BD as described above.

The argument about a second drain aiding in the removal of plugs/clogs doesn't make much sense to me so I'm reluctant to comment. Seems like turning off the pump would relieve even more suction than a second drain and therefore similarly aid in clog removal.

If a person has space for a SC or vortex I would highly recommend it. Pays dividends in pond water quality and makes pond maintenance easier.

Ccoombs1 you are correct on the size of the pond if the sides are vertical and the bottom flat. But very few liner ponds are built this way so most ponds end up with less water than what the measurements say they should have. I have found that using 50 to 60% for ponds without rocks on the bottom and 40 to 50% for ponds with rock to be usually pretty close. So when I said less than a 1000 gallons it will probably turn out about 800 to 900 gallons. I do agree with what you said about the magazine on the bottom drains. But I would have said that if the magazine said this than they have no idea what a bottom drain for a pond is. A bottom drain for a pond has an anti vortex lid on them to keep fish out. They would be thinking of a pond bottom drain as the same as a swimming pool bottom drain which can suck a person down so tight as to kill them. This can't happen with a properly opperating pond drain.
Mike

Bbrigs, I didn't take it as an attack, I just wanted to explain why I think it's the most important thing you can do when building a big pond. When we built our pond ten years ago we included a bottom drain, only because the salesman explained the premise behind it.
We have a gravity fed system and had one filter tub the first year, the second year we added a second and third filter tub.
Then I wanted a small pond adjoining our rose garden, so Cliff took this idea and made the small pond a biological pond for the big pond. It it eighteen feet away from the main pond and after the water leaves the three filter tubs that are daisy chained together it travels 18 feet underground and spills into the biological pond. The water then travels through the bio pond getting scrubbed by all the vegetation in there then exits the bio pond, travels back underground and spills into the main pond from under the small wood dock in back of the main pond. Then we added a skimmer under the wood dock to catch all the surface leaves etc. We only use the skimmer in spring and fall.
We have been talking about daisy chaining another tub or two to the existing system, but so far we've been managing with what we have.
You are absolutely right bbrigs when you say a good filtration system is essentially, my point is to start with the bottom drain, then you can add more filtration, bio and mechanical, you can make the pond bigger (we did that as well --two times) you can add a skimmer, more waterfalls,
etc...all this can be done after. That's is what I mean when I say the BD the single most important thing you can do for your pond, start there and everything else can be made bigger and better and more efficient later on.

Rose, We have a lot of fish, about 10 large koi, 3 large orfes, 2 goldfish and several medium koi that are off springs of our koi.

Here is a link that might be useful: Pond plans and diagrams.

Pete, If you have a small yard, think about a different shape.
Do you have a patio or deck? An eight foot round would take up a lot of room, maybe something like 6' x 20' foot long, that is off to the side, (so that it doesn't take up much yard space) with a couple of subtle twists would be nice. You didn't say if you want it to be formal or natural.

Joann

I removed a huge deck this past autumn from the back of my house. It's width spanned the entire back of the house. this did not leave much room for anything else. I did have one area of the yard that received a large amount of sunlight all afternoon. Here I had blueberry bushes, grapevines, fig trees. Because of the small area, I kept everything in pots. Pruning them as time went on. They actually did very well. Now, with the deck removed, we put in a much smaller patio. only 18x13. I feel like an artist with a blank canvas in front of me. I can finally plant my potted trees and bushes, and put in that pond I've always wanted. I want to do it right the first time..that is, buy the best equipment I can afford. I made a beginner's mistake when setting up my saltwater reef tank by trying to "just get by" with lousy equipment. I've spent more money trying to upgrade. If I just did it right the first time. I was thinking of putting the pond in the area where there is much sun, but I know that's a no-no as far as algae blooms...I've had container ponds in the past with water lillies. I know these lillies need at least 6 hours of sun. I wont get that if I leave my pond in it's current location. The other option is to put it adjacent to the house. There's only soil there (after the removal of the surprise concrete slab under the deck was found) But I got flack from the wife. Uggh, this is supposed to be a good thing right. Sorry to vent people. Hmm.. my anniversary is coming up in two weeks. Maybe if I do good, (diamond wise) she'll do good...pond location. LOL!!!

Pete, Get your wife involved with the pond, and maybe you can forget the diamonds...:) You have a wonderful opportunity to build and pond and incorporate a patio in your design. You said about an 13 x 18'patio...Why not wrap the pond around the end of the patio -- down the end of the patio (the 13' wide part) run the pond down about 6 feet, and along the length (the 18' long part) of the patio run a section down about 8 feet, and from there -- run the pond out about 20 feet into the end of the yard (which would be down the end of your property, leaving the middle and the other end as is...Think about a beach section to your pond that goes right up to the end of the patio. This way your fish will be right up to you on your patio. I can picture it in my head, but don't know if you can, if this interests you, let me know and I'll elaborate further. BTW, what kind of patio?

Joann

I think she doesnt want the pond right next to the house. This is the area was freed up by the deck removal. I think she just wants grass there. But maybe I can convince her, if I draw it up for her on paper, I can show her how nice I can make it. The patio is composed of red/blackish rectangular brick. with rounded off edges. You know what, maybe I can post some pics of the area tonight after work, so you can all maybe get a better picture of the area?

Yes, good idea...my imagination is running overtime, I can picture a beautiul pond ending into part of the patio. Is the patio built yet?

Joann

Yes, the patio is built, but the rest is all soil. over on the left side of the patio if you're facing the back fence. Hey, I may have some pics right now so you'll get the basic idea. How do you post on here?

You have to open an account on photobucket, then you can post to here. after they are posted on photobucket, you highlight the url and copy it then come here and type in

>img src=" in here paste the url that you copied --then on the end add this "you need to reverse the > to this (If I did it the right way on the example it would show up as a red box)