Starting up a koi pond

[Murica]

Hello,
As the title suggest, next year I'm putting in a koi pond. Wicked excited!

I'll have random questions here and there... First one is, my walls are going to be cinder block with spray on liner (fish safe). Would the bottom be better if it's a cement slab with spray liner or bentonite clay?

 

[norfolkgarden]

I would go with the concrete slab.

But I have never worked with the bentonite clay.

 

[Murica]

I would go with the concrete slab.

But I have never worked with the bentonite clay.

Did you put the bottom cinder blocks in the concrete or did you put them on top of the slab and attach with mortar?

 

[norfolkgarden]

The concrete pond was pretty basic.

About a 6' x 3' shaped hole, slap in some mortar. add metal reinforcement from Lowe's and cover it with more mortar.
Back in the 90's when little backyard ponds were the new garden fad.

A week muriatic acid wash, make sure you wear eye protection and clothing protection,
drain and fill a few times and ready for rosey reds for mosquito control.


I am partial to heavy liner ponds.
We still have a 10' x 10' in the backyard that is about 14 years old now. But it gets very little direct sun to degrade the exposed parts of the liner.
The liner is backed by vertical 3/8 inch styrofoam and folded up and back down over the styrofoam. Dirt up against it holds it in place and the five gallon and 3 gallon planting containers for the marginal plants rest on the inside step, plus the water pressure keep it from bowing in.
I went with creeping liriope as a green border for the pond to help hide the liner. The typical "rock necklace" would look really out of place in our yard.

Stepping stones 2 feet away from the edge of the pond and not walking right up next to it keep it in good condition for the past 14 years.

These are just glorified goldfish bowls without a bottom drain.

The 10' by 10' pond supports five or six 6" comet goldfish without any filtration or a fountain for oxygenation.
Random pond weeds and a whole bunch of marginals and that's about it.
I haven't done anything with it in maybe 5 years. It's self sustaining but not a show piece right now.

If you are digging a large koi pond that is at least 2 ft deep to prevent the herons from fishing out your prizes you will want something considerably more elaborate with real filtration.
A pond without a bottom drain has been described as a toilet without a drain in one of the books.
[emoji6]

I read a lot about bentonite clay but it never made me really comfortable.
There are hundreds or maybe even thousands of ponds that have used it just fine according to the reading.
The context seems to be large multi acre farm ponds.

My personal experience is with play toys in a suburban backyard.

 

[Murica]

The concrete pond was pretty basic.

About a 6' x 3' shaped hole, slap in some mortar. add metal reinforcement from Lowe's and cover it with more mortar.
Back in the 90's when little backyard ponds were the new garden fad.

A week muriatic acid wash, make sure you wear eye protection and clothing protection,
drain and fill a few times and ready for rosey reds for mosquito control.


I am partial to heavy liner ponds.
We still have a 10' x 10' in the backyard that is about 14 years old now. But it gets very little direct sun to degrade the exposed parts of the liner.
The liner is backed by vertical 3/8 inch styrofoam and folded up and back down over the styrofoam. Dirt up against it holds it in place and the five gallon and 3 gallon planting containers for the marginal plants rest on the inside step, plus the water pressure keep it from bowing in.
I went with creeping liriope as a green border for the pond to help hide the liner. The typical "rock necklace" would look really out of place in our yard.

Stepping stones 2 feet away from the edge of the pond and not walking right up next to it keep it in good condition for the past 14 years.

These are just glorified goldfish bowls without a bottom drain.

The 10' by 10' pond supports five or six 6" comet goldfish without any filtration or a fountain for oxygenation.
Random pond weeds and a whole bunch of marginals and that's about it.
I haven't done anything with it in maybe 5 years. It's self sustaining but not a show piece right now.

If you are digging a large koi pond that is at least 2 ft deep to prevent the herons from fishing out your prizes you will want something considerably more elaborate with real filtration.
A pond without a bottom drain has been described as a toilet without a drain in one of the books.
[emoji6]

I read a lot about bentonite clay but it never made me really comfortable.
There are hundreds or maybe even thousands of ponds that have used it just fine according to the reading.
The context seems to be large multi acre farm ponds.

My personal experience is with play toys in a suburban backyard.

So you let the mortar dry, add rebar, then mortar on top? Or did you pour, add rebar when it was still soft..

 

[norfolkgarden]

So you let the mortar dry, add rebar, then mortar on top? Or did you pour, add rebar when it was still soft..

Keep the mortar on the dry side. Not dusty, but really close.
We started early in the morning, let it set up a little, mashed in the reinforcement and added a second (much lighter) coat on top.

It will slump horribly if it is too wet or to thick on the top coat.

Keep in mind this was some of the least professional concrete work you will have ever seen in your life.
[emoji6]

It was also my inspiration for loving liner ponds.

What size pond are you planning?

 

[Mortie31]

In my Koi pond 28’ x6’ x 5.5ft deep, I used 2 bottom drains with 4” pipework, I cut rebar to fit the hole and then ordered ready made concrete and laid a 6” slab. This was allowed to dry completely, the walls were built using hollow 18 x 9” blocks and back filled with concrete. I chose fibreglass instead of a liner. I believe bottom drains to a gravity fed filter is the best way for keeping the pond bottom clean long term, unless you plan to keep bottom feeders like sturgeon.

 

[Murica]

It's going to be an 8x15 by about 3-3.5 feet deep. Around about half the pond, I'm going to put a 2 foot deep by 2 feet wide ledge for lilies and other plants. In one corner I'm going to have a solar powered waterfall. When I do get livestock, I'm planning on only getting enough for a very light bio load so that way I can skip on the bottom drain, just gonna have to manually skim and water change from time to time

 

[Murica]

Forgot to add, the waterfall will be enough to turn over a large volume of water, not the tiny trickle solar powered ones you see at Lowe's, and all is dug out by a shovel lol no mini excavator for me

 

[norfolkgarden]

It's going to be an 8x15 by about 3-3.5 feet deep. Around about half the pond, I'm going to put a 2 foot deep by 2 feet wide ledge for lilies and other plants. In one corner I'm going to have a solar powered waterfall. When I do get livestock, I'm planning on only getting enough for a very light bio load so that way I can skip on the bottom drain, just gonna have to manually skim and water change from time to time

So a small one.
[emoji4]

We can keep a single half grown koi (14") in the 10'x10'x18" heavily shaded pond until the first really hot days in late summer when the O2 drops and the koi jumps out looking for greener pastures.

Spent several years trying with 2 or 3 6" koi and very successful for the first 2 years until they get some size.
Without decent aeration and some filtration the pond won't hold enough O2 consistently.
Koi are notorious for rooting around (literally) and eating your plants new growth.
Keeping random underwater pond weeds stocked to absorb nitrates and phosphates may be difficult.
Marginals help to some extent but the 8" koi will flip into a planting bucket submerged 2" below water to root around in the bucket.

Goldfish are less destructive. Top out about 8".
*Bright* scarlet, well patterned, comets are easy to find locally, and a bit less expensive than a similarly well colored koi.
[emoji6]

Wow, can't even remember the variety. Used to know top 15 koi varieties.
Other than admiring an Ogon or Ginrin I'm no longer very interested in the koi.

(Scale of fish size to pond looks a lot more realistic with the goldfish.)
Same goldfish for the past 5 years when I have basically ignored the pond completely for other projects.

You may want a dramatically larger pond or considerable mechanical filtration or some nice goldfish.

 

[norfolkgarden]

In my Koi pond 28’ x6’ x 5.5ft deep, I used 2 bottom drains with 4” pipework, I cut rebar to fit the hole and then ordered ready made concrete and laid a 6” slab. This was allowed to dry completely, the walls were built using hollow 18 x 9” blocks and back filled with concrete. I chose fibreglass instead of a liner. I believe bottom drains to a gravity fed filter is the best way for keeping the pond bottom clean long term, unless you plan to keep bottom feeders like sturgeon.

Sounds beautiful!
Nice and deep. No problems with herons or egrets.
[emoji4]

What type of koi do you keep?

 

[Murica]

Are the bio and mechanical canister/uv filters good? I was thinking having that pump up to my waterfall which obviously would help my filtration. And brand recommendations?

 

[Gareth elliott]

Following along, mine is a liner not concrete. About 8-900 gallons.

 

[Jl330]

I'm following this. I have a huge area to work with but not sure if I want to take on another project. I'd want low maintenance if I do it. Biggest concern is weather. We see everything from 115 degree summers down to -10 degree winters. Sometimes in the same week it seems. KY is weird.

 

[norfolkgarden]

Are the bio and mechanical canister/uv filters good? I was thinking having that pump up to my waterfall which obviously would help my filtration. And brand recommendations?

I don't really know anything anymore. It has been too long.

Back when I was on the pond forums a lot of people talked about using UV to control algae. But just like in a reef tank, you are keeping it dead but you are not removing the nitrates and phosphates that caused it in the 1st place.

Only excellent piece of advise is base pump purchase on electrical efficiency *not* price.
An electrically efficient pump will generally pay the difference in added purchase price within 3 months usage. And then after that it's all gravy.

Honestly I don't even remember which type of pump was better.
I just remember little giants were cheaper and American made, but they were not as electrically efficient 15 years ago. That may have improved since then.
The little giants were one type of physical pump and the ones we bought that were more electrically efficient were a different physical type of pump.

I don't even remember what the name of the competitor was that we actually bought.

 

[Mortie31]

Sounds beautiful!
Nice and deep. No problems with herons or egrets.
[emoji4]

What type of koi do you keep?

Thankyou, I have imported Japanese koi in my main pond and a mix of Japanese koi, ghost carp, golden Orphe and Rudd in my smaller pond. I have vertical sides to stop herons etc, as they need to wade to catch effeiciently...

 

[Mortie31]

It's going to be an 8x15 by about 3-3.5 feet deep. Around about half the pond, I'm going to put a 2 foot deep by 2 feet wide ledge for lilies and other plants. In one corner I'm going to have a solar powered waterfall. When I do get livestock, I'm planning on only getting enough for a very light bio load so that way I can skip on the bottom drain, just gonna have to manually skim and water change from time to time

If you are still at the design process I would really think about a bottom drain, it can empty directly into your filter. One main benefit people forget is that waste remains larger as it doesn’t get mulched by an in pond pump, which means it settles easier, is easier to remove and water clarity is improved..

 

[Mortie31]

You will defiantly need a UV filter to control algae, they actually don’t need to be that strong, but if you are in a position with lots of direct sun you will need a larger one, for example I have a 110w on my 5000 UK gallon pond.

 

[Gareth elliott]

You will defiantly need a UV filter to control algae, they actually don’t need to be that strong, but if you are in a position with lots of direct sun you will need a larger one, for example I have a 110w on my 5000 UK gallon pond.

I also use a uv, anecdotal but i also haven’t had an anchor worm outbreak since installing mine. Would get every few years from some bird landing and bringing the copepods with them.

 

[dbraun15]

Thinking along the same lines about doing a pond in the next year or so...anybody have any pics of their current setup for motivation?