I think I can build a garden/koi combo pond

[velokoi]

Ok, I think this is attempt 9, maybe 10 who knows, but this is my largest build yet so I thought I would post my design here instead of just reading the comments on other's designs and winging it till I get it right. I just posted my bog filter design in the DIY channel, and I am looking to see if anyone is willing to poke holes in my designs before I start to build. Plan is to start digging in 7 days. Once I start I can post pictures along the way to help the next person.

1) This will be around 30' x 30' with a depth of between 3 and 4 feet and total gallons of around 20k.
2) Bogs will provide 100% of the filtration ... I hope.
3) Streams should provide more than adequate aeration.
4) Total number of fish is unknown, will grow as I gain confidence in filtration and maturity of pond.
5) I am replacing an existing pond that is broken down, shallow and no longer holds water
6) Current pond is 10'x8' and 3' deep (keeping this one)
7) No bottom drain, just lots of rocks at bottom, hopefully some tall lilies at bottom


I am using 6 upflow 100 gallon stock tanks for the primary bog filter 60 sq feet.
I am feeding the bogs from 2 skimmers (16" savio) and one in pond pump, 3 lines
I feed the bogs in pairs from each pump (6,100 gph) using 3" pipe with a 2" Y to each bog at end
Bog set 1 feeds a trickle falls/stream about 5' wide and 15' long
Bog set 2 feeds an instream bog and leads to 5 water falls and a second instream bog
Bog set 3 feeds a 3rd bog before returning to the pond.
Total stream based bogs (6"-8" gravel) = 200 sq feet
Bog/Pond SF ratio of 260/840 or about 30%, plus another 250 SF of streams
Overflow stream leading to a frog pond that dries out in summer.

After I dig out the pond to about 3' of depth I plan to place figure 8 blocks around and fill each hole with a rebar and then concrete.
I want a 3' drop from the edge all around the pond to reduce racoon attacks (worked in last few ponds)
Place carpet all around bottom and tops of blocks to protect liner
Place 45 mil liner (one piece or maybe glue to smaller pieces)
Place and mortar edge stones, skimmer and plumbing, water fall liners to edge of pond.
Place and liner streams and bogs going into pond (top of bogs raised 4 to 10 feet above pond)
Planning for pumps to drop to around 4 to 5k gph for a total of at least 12k gph (anjon 6100x3)
Dump in some test fish and some of my existing filter media/plants to seed pond.
Sketch below with some green and blank areas for maple trees and a tan french drain beside the pond.

Next year plan to build a deck, bridge and pagoda around the pond and start looking for more koi. Going for a Japanese garden look.

Thanks for any help.

 

[Mmathis]

Oh wow, that is way over my head…..but impressive.

My only question is why let the frog pond dry out in summer?

 

[velokoi]

We will eventually address it once we restore the primary pond. Both ponds current run dry for August and September and then fill up each October/November. Before we replace the liner in the overflow pond we want to get a feel for how a restored pond will alter the water dynamics of the area. This is also why we are placing a french drain along one side that still feeds into the lower pond.

 

[Jhn]

How are your stream based bogs working? if it is being fed by the container bogs so water just moves across the top, these bogs aren’t going to be as effective as an upflow bog. As channeling will happen with flow across the top.

Nice build and if the bogs are built correctly, will have plenty of filtration.

My pond is a similar size to yours and has to upflow bogs at either end totaling 200 sq. ft. Or so in bogs as the only filter and works great with a crap ton of fish and turtles in there.

 

[velokoi]

Stream based bogs will be feed by the container bogs and just flow over and maybe through with no clean out option and no upflow. While the streams are not efficient, my hope is the 6 container bogs will be able to handle the bulk and the stream bogs will be mostly for looks and to add some filtering. For sure a potential issue, but not sure I want to alter the design to fix it until it actually fails. The stream bog design will limit the amount of fish, but I am hoping my upflow bog design is better than average and will take up some slack.

 

[Jhn]

Anywhere you put plants will help, but those streams aren’t going to be as effective as you would like. So really you only have 60 sq.ft. of bog for 900 sq.ft. of pond surface, when you should be shooting for 10% of your surface area in bog surface area.

Don’t know if your upflow bog design is better than average, but it is definitely better than any store bought filter. I have container bogs around a turtle pond dumping into it and they work well.

I will say not sure why you went with the containers for bogs as opposed to excavating a larger area at the head of the streams and using water matrix blocks and graduated rock sizes for the bog. In my mind your pond isnt going to be cheap either way to build, so if you have the space, the bog area would look much more natural in the ground as opposed to stock tanks.

Something like this for example

 

[GBBUDD]

a ten foot drop for a waterfall is evaporation in a big way add a little wind and youll have more than evaporation you'
you' ll also have water loss/

but i agree with @Jhn the up flow bogs are key i also have stagnant bogs and while i love them to death they do next to nothing for the benefit of the pond/ 30% is more where i would aim for the bog to surface area

i would not use any preforms tubs. they are actualy harder to work with than is liner and you can dooooo sooo much more to a liner over hard plastic

 

[GBBUDD]

your title sounds like myself when i first thought of building my pond and 6 years latter it caught aquascapes attention to the point Greg Whittstock came out to see my first build, so yes it can be done. I have seens @Jhn's set up it was very cool and unique. his little 300 gallon preform tubs for the turtles was very impressive

 

[velokoi]

First, GBBUDD, I love your pond setup - just watched the video in your blog, life goals we shall call it. jhn I like how natural yours looks. Both are things I am going for in the final look so that my wife can have plenty of planting areas.

Bog containers over liner because of two reasons, one they can't be punctured by a racoon, which will be around the pond (I have found steep edges keep the fish safe from our racoons). Second because I have found them easier to clean out. I have used them on every pond I have built, so my go to I guess, but this is the first large pond and I have more mistakes under my belt than perfect ponds. Most of my failures have been because my bog to fish ratios have been off, which maters more than bog to pond ratio .. yes? so I will be able to have 60 sf of bog worth of fish plus a few more because of the stream bogs which can't hurt. This should support 6x my last pond build based on that increase alone. My biggest concern is how to racoon proof the stream bogs as they have destroyed them before. Still issues I am thinking through as I get closer to pulling the trigger, so thanks for the input.

Evaporation will be constant, but not an issue in Oregon with fresh well water available anytime. The pond stays full with a shattered liner now for 8 months out of the year. 10 feet may seem like a lot, but when it is 25 feet away, near ground level and will flow over 40 feet 10 feet is almost needed to keep the water moving, and it is the landscape I was given so not a choice. I love moving water and the streams and waterfalls are 50% of the pond to me. I have had a stream in every pond I have done except one, but yes this is a larger scale than previous builds for me.

I guess another question as long as the stream bog is supporting good growth in plants, then by that alone it is working as a good filter, correct? Then I will check back with you both in 2 years when I rip them out and replace with a 20' liner bog instead, but what else am I going to do in 2026? I will post more pictures as I move through my final design and start my dig out.

 

[Jhn]

@velokoi, Yes, plants in your streams, around the edging of the pond in between the rocks, anywhere really all helps in the nutrient uptake from all the critters in your pond that will produce waste. I would make some areas where you can put pots for water lilies in your pond, little pits That the pots can drop in and make a shallow area maybe 2’ deep out in the middle to keep raccoons. Or if you want to be abit out side of the box, I put a planting pit in the middle of the pond about 10” deep around 8’x4’ wide in about a foot of water and filled it with pickerel rush which is now a giant stand of it. Also have a 2’ deep part of the pond that is nothing but a Lilly planter where the lilies have free roam to grow. Just giving various ideas to think about.

I assume you are using a piece of equipment to dig the pond? Are you going to be using large rocks around the edges and in your stream? If you aren’t consider doing so it makes a world of difference in the look of the pond. Also, in spots where you set rocks that look like the edge of your pond, let the liner come back in behind and cover it with gravel or even as @GBBUDD did fill an area with sphagnum/ peat moss and plant pitcher plants etc. in there, makes for interesting areas around the pond. Using dead wood in and around the pond, as well makes a huge Difference and you can find fascinating pieces if you keep your eye out for them.

Looking forward to see pics of your build sounds like it will be very cool looking. You sound abit like @GBBUDD and myself he and I over the years have constantly been adding onto our ponds as we come up with other ideas. Also, being a tinkerer that can’t just leave things as they are helps.

 

[GBBUDD]

My biggest concern is how to racoon proof the stream bogs as they have destroyed them before. Still issues I am thinking through as I get closer to pulling the trigger, so thanks for the input.

one option is to get your hands on 8oz if not 12 oz non woven geotextile the 8 oz when you gho to cut it with a utility blade you'll get about 20 feet of cut before your looking to replace the utility blade so it will withstand a racoons finger nails.
now 12 oz is insanely tough stuff can a racoon or bear get through it yes but that will take a considerable amount of time and i don't see any reason that they would unless you had like a fish cave behind the fabric.

third is a guarantee, concrete cloth the little buggers won't get through that in a million years but it is pricey

10 feet may seem like a lot, but when it is 25 feet away, near ground level and will flow over 40 feet 10 feet is almost needed to keep the water moving

when people say 10 foot water fal here it generally means a single drop . but it looks like your talking your set up will cover ten feet in elevation between start of the pond to the top of the stream and a waterfall. which in that case is ideal.

you can build your pond any way you like it is your oasis. to me seeing plastic tubes and or trying to cover them up is less than ideal. but again it' it's my 2 cents which means next to nothing. as you saw i'm more having the pond look as natural as possible

I have had a stream in every pond I have done except one, but yes this is a larger scale than previous builds for me.

just look at it as a project in stages

the stream bog is supporting good growth in plants, then by that alone it is working as a good filter, correct?

the stream absolutely helps it oxygenates the water and it traps the sediment in the water column as well as sucking out phosphates ammonia and nitrates all things that plants thrive on. if you are pumping water into preforms and plants in that yes it would be easier to clean and when you clean them out the build up is contained and easy to keep from mixing back into the water column. i just shut down my pumps and pull the plants that just sit in the stream there is no container. but it does mean you need to be careful what plants you let just run wild in the stream

 

[GBBUDD]

take lots of photos of your build many here like you said have made these mistakes god knows i'm high on that list and maybe able to help save you some time and money

 

[velokoi]

Thanks for the additional feedback, I have made many mistakes and will likely make a few more this time to share with the group. My target rules for building the pond include no liner edge or plumbing visible, rocks should look natural vs castle walls or paths, nothing round or square and lots of plant areas in and out of the pond. Photos will start next week with the before. I am using an excavator to help with digging and rock placement. I am planning to limit my rock size to 500# (2 to 3 feet ish long) but also mix in smaller rocks and as mentioned even no rock at times. I like the idea of felt over and under the liner for the streams and bogs, still debating if I should mortar the streams under the gravel as well (likely will try the felt this year and only mortar if needed. I don't mind redoing them next year as I consider them a long term design work with lots of failures and redesigns for the streams.

My largest falls will be 24" as I have found more makes too much splash and noise for my taste. Most falls will be in the 12" range, I am planning for 10 to 20 falls in various places along about 75 feet of total streams including 6 coming out of the bog containers. Bog containers will be half buried in ground and rocks/plants around the rest to hide 99%. Target of 0% plastic visible, but a little is ok in the winter. I also can't make them just mortar and stone statues, so will take time next year too. Moss will be everywhere we can get it, plenty around our property.

Target is fish ready and holding water with pond done and streams and bogs functional before the fall rains in October. Then a couple of years of tweaks. My last main pond at our previous home had 3 major redos where we took the liner out and redid the pond 100% over 20 years. I want to avoid that this time.

 

[GBBUDD]

sounds like you have been around the block a few times with ponds, more so then i im in year 7 but you can always pickup tricks from even a rookie i have found watching you tube pond builds .
i also put together a large length showcase don't know if you're interested in this much or not but I'm sure theres a few tips tricks in there .

Honored and Proud to have been chosen Aquascapes DIY pond of the year for 2023. 12,000 Gallon Koi Pond, Full Build

Large KOI pond with a Wetland filter, Negative edge and an intake bay. Start to finish, Building, Maintaining and expanding / seaming . https://www.facebook.com/watch/live/?ref=watch_permalink&v=687652723148180

www.gardenpondforum.com

 

[velokoi]

I have read it twice, very impressed by your work.