Go Big or Go Home, First Timer Building a 2500gal Koi Pond

[eroyal93]

I’ve been stalking this forum for months gathering research, so I figured it’s about time I join!

It’s been my and my husband’s dream to have a zen garden since we were children, and we finally decided this year to do it! But when I have a dream... baby, I dream BIG. The result: a 95% DIY Zen garden with a 2500gal Koi Pond built into a slope in our back yard.

Here’s where we’re at:

We’ve already dug the trench for the retaining wall side of the pond. It’s currently more of a moat than a trench as we wait for the concrete guy to come pour the first part of the footer and set the rebar.

I’ve completed the research and design for the electrical components (buried line, running a new circuit from an outdoor breaker box to 4 outlets at various places around the pond).

I’ve completed the research and design for the plumbing (mostly PVC, average 2” pipe).

I’ve completed the research and design for the bottom drain (DIY 4in housing, 3in pipe) and vortex filter (gravity fed from BD, 55g barrel).

I’ve mostly completed the research and design for the shower filter, just finalizing the media choices (3 tier [bioball, lava rock, biohome/pumice], UV filter in the bottom).

To Do/Next Steps:
- Finalize runoff/drainage layout and design
- Research and design bog filter
- Finish construction of retaining wall and general leveling of pond
- Dig areas for plumbing, filters, water tanks, etc
- Complete physical construction of pond structure
- Set other physical elements
- Fill and cycle
- Finish landscaping other garden elements

Glad to be here, and thanks for all the information y’all have already provided and I’m sure you’ll continue to contribute!

(P.S. Forgive the manic journaling—I’m ADHD, artistic, and VERY much a visual learner! It’s definitely overwhelming all at once, and confusing as designs/specs have changed as I’ve done research and started building. So if you’re curious and want more explanation on my pictures, feel free to ask!)

 

[Tula]

Welcome We love to follow pond builds !

You've certainly done a lot of research, which is wonderful. I'm no expert but noticed solar power mentioned . Where are you planning on using solar power and will it reliably run your pump 24/7?

I don't know very much about vortex filters ( mechanical filtration ) , will one 55 gallon barrel be enough for the size of your pond?

It's great you're planing a shower filter for biological filtration. I used to have one until it was crushed by a falling tree

Again, welcome...we're happy to have you

 

[cas]

Welcome to the forum.
I'm going to love following your pond build! Keep the pictures coming!

 

[eroyal93]

Welcome We love to follow pond builds !

You've certainly done a lot of research, which is wonderful. I'm no expert but noticed solar power mentioned . Where are you planning on using solar power and will it reliably run your pump 24/7?

I don't know very much about vortex filters ( mechanical filtration ) , will one 55 gallon barrel be enough for the size of your pond?

It's great you're planing a shower filter for biological filtration. I used to have one until it was crushed by a falling tree

Again, welcome...we're happy to have you

Solar was an idea I explored, but ultimately it was too expensive and unreliable for our needs. The initial idea was to use solar if it seemed like the initial investment would pay off in a few years, but ultimately it was just cheaper in electricity use to run the lines and pay for the power.

As for the vortex filter, based on a commercial design that was a 150gal drum for a 5,300gal pond, it seems to be 1gal of vortex filter for every 35gal of pond, so I need around a 60-65gal vortex filter for my use. For the price jump from a 55gal barrel ($10 used) to a larger conical tank ($100-$200+), I’ll deal with cleaning the vortex filter a little more often!

 

[eroyal93]

Welcome to the forum.
I'm going to love following your pond build! Keep the pictures coming!

Will do! I’ll happily be posting pictures as progress happens!

 

[Lisak1]

@eroyal93 - welcome to the GPF!

You have indeed done a lot of research! One question - have you considered a bog filter? So much simpler, so much prettier, so much less work... I know you said you would happily clean your vortex filter, but I'd be willing to bet that job will grow tedious as time goes on. Spend that time puttering with your plants or watching your fish instead!

And your bottom drain - are you building a dedicated koi pond? No plants no rocks, just fish and water? If not, I'd skip that bottom drain.

 

[eroyal93]

@eroyal93 - welcome to the GPF!

You have indeed done a lot of research! One question - have you considered a bog filter? So much simpler, so much prettier, so much less work... I know you said you would happily clean your vortex filter, but I'd be willing to bet that job will grow tedious as time goes on. Spend that time puttering with your plants or watching your fish instead!

And your bottom drain - are you building a dedicated koi pond? No plants no rocks, just fish and water? If not, I'd skip that bottom drain.

I have! I’ll have a bog filter right after the shower filter—it’s the small pond at the top of my concept drawing. The vortex filter is just acting as a prefilter—I’m doing both the shower and bog my biological filter because I can’t make either large enough to handle the koi pond on its own, (media too expensive for the shower, area not large enough for an appropriate sized bog).

To the other question, we plan to have plants, around the edges, but no rocks on the bottom whatsoever. I first concepted the pond without a bottom drain, but since we’re building from scratch, I thought we’d go ahead and add one in because retrofitting is SO much harder if it turns out we need one!

 

[Mmathis]

(P.S. Forgive the manic journaling—I’m ADHD, artistic, and VERY much a visual learner! It’s definitely overwhelming all at once, and confusing as designs/specs have changed as I’ve done research and started building. So if you’re curious and want more explanation on my pictures, feel free to ask!)

LOL, I totally know where you are coming from — I, too have ADD (just not the “H” part), and am totally a visual learner! Your plans are impressive!

Agree that a bog filter (wetlands filter, eco filter) would be perfect, but you don’t want to put it AFTER the shower, but BEFORE it. You want as much of the nutrient-rich water to go through your bog —otherwise you are defeating the purpose of having a bog.

How big are you planning to go (apologize if you already mentioned that)? I saw one reference to “small,” so wondering if your pond will be large enough for koi.

 

[Lisak1]

Good catch @Mmathis - if you need a pre-filter ahead of a bog at all, it would be to catch large debris. Otherwise you want the bog to get first dibs on that good water! I see you have "always mechanical filter before biological" so I think you understand the concept. I'm not familiar with vortex or shower filters, but I'm assuming they do both mechanical and biological. Maybe you want to plan to send some water to the bog and some to the vortex?

 

[mrsclem]

2500 gallons is ok for a few koi but while you are planning, figure how many koi you want and remember, they will breed! Go as large as you can now so you are not redoing your pond in the next few years.

 

[Tula]

If you have the space, I'd recommend spending the extra money for the larger conical shaped vortex tank. I have 4 sixteen year old koi....and believe me, they really create waste .

We added a small bog this year and are really enjoying it

 

[j.w]

@eroyal93
Wow I'll say you did your research! My head is spinning
Great planning ahead!

 

[poconojoe]

Awesome planning! Can't wait to follow along. Post up some pictures as you progress.

I'm another proponent of bog filters. Cleaning out any store bought or homemade filters can get old real quick and take the enjoyment out of owning a pond.

You said you dont have enough room for a big enough bog. Surface area is used to figure the size of the bog, not gallons, as one would think. The basic formula is the bog's surface area should be at least 30% of the pond's surface area. Go bigger to play it safe or if you feel the need.

A bog won't require constant cleaning, will keep your water crystal clear and provide another spot to grow a bunch of awesome plants.

I went through years of using all kinds of filters and UV lights which were never adequate. Plus my pond became overcrowded since my fish keep reproducing. Since adding on the bog and selling all my filters and UV light, my water is amazingly clear. It's never been this clear in over a decade. I highly reccomend it.

It's up to you...maybe run the bog and see how it goes. If it's not adequate, add the other filter into the plumbing. Odds are it will be fine with just the bog, as long as it's built and sized correctly.

 

[eroyal93]

LOL, I totally know where you are coming from — I, too have ADD (just not the “H” part), and am totally a visual learner! Your plans are impressive!

Agree that a bog filter (wetlands filter, eco filter) would be perfect, but you don’t want to put it AFTER the shower, but BEFORE it. You want as much of the nutrient-rich water to go through your bog —otherwise you are defeating the purpose of having a bog.

How big are you planning to go (apologize if you already mentioned that)? I saw one reference to “small,” so wondering if your pond will be large enough for koi.

The overall size will include a little over 2.5’ of water, and at least 6x12’ of space at that depth, so it should be enough for Koi, if only “just” deep enough. I figure we can always add another brick to the retaining wall and raise the water level higher if it seems too shallow in the end.

I definitely see your point about the bog, though... I may have to go with someone else’s suggestion of diverting some water to the shower and some to the bog. It’s already designed that way for the shower filter clean out anyway!

Good catch @Mmathis - if you need a pre-filter ahead of a bog at all, it would be to catch large debris. Otherwise you want the bog to get first dibs on that good water! I see you have "always mechanical filter before biological" so I think you understand the concept. I'm not familiar with vortex or shower filters, but I'm assuming they do both mechanical and biological. Maybe you want to plan to send some water to the bog and some to the vortex?

That’s a pretty good idea of splitting the water. I may just do that! (Oh, and vortex is mechanical, shower is meant to be mostly biological.)

If you have the space, I'd recommend spending the extra money for the larger conical shaped vortex tank. I have 4 sixteen year old koi....and believe me, they really create waste .

We added a small bog this year and are really enjoying it

I may upgrade if I can in the future, but right now budget is a huge factor with taxes coming up!

2500 gallons is ok for a few koi but while you are planning, figure how many koi you want and remember, they will breed! Go as large as you can now so you are not redoing your pond in the next few years.

Definitely considered! The size we’ve settled on is mostly based on the cost of the EDPM liner. It’s one thing we’re not skimping on, and we’re already looking at needing a 20’x20’. (I originally designed a “1/4 circle“ shape that was about 16”x16” that was 3’ deep until I looked at the cost of a 30’x30’ liner X.X)

My husband is going to be the one really keeping the Koi, and he said he’d only want to be caring for maybe 4-6, so we should have enough room for that number. What to (humanely) do with the inevitable progeny is something we haven’t quite gotten to yet, but it’s been thought about!

Awesome planning! Can't wait to follow along. Post up some pictures as you progress.

I'm another proponent of bog filters. Cleaning out any store bought or homemade filters can get old real quick and take the enjoyment out of owning a pond.

You said you dont have enough room for a big enough bog. Surface area is used to figure the size of the bog, not gallons, as one would think. The basic formula is the bog's surface area should be at least 30% of the pond's surface area. Go bigger to play it safe or if you feel the need.

A bog won't require constant cleaning, will keep your water crystal clear and provide another spot to grow a bunch of awesome plants.

I went through years of using all kinds of filters and UV lights which were never adequate. Plus my pond became overcrowded since my fish keep reproducing. Since adding on the bog and selling all my filters and UV light, my water is amazingly clear. It's never been this clear in over a decade. I highly reccomend it.

It's up to you...maybe run the bog and see how it goes. If it's not adequate, add the other filter into the plumbing. Odds are it will be fine with just the bog, as long as it's built and sized correctly.

Yep, I came across that bit of info about surface area sizing! The area dedicated for the bog still doesn’t have enough room to accommodate 30% of the surface area of the pond. This is in the corner of my property, so I’ve got hard boundaries on the north and west, and the pond is in a fixed location to the south. With that in mind, I’ve only got about 6ft by 3ft (MAYBE 3.5ft if I go closer than 2ft from the property line) for the bog, and my pond’s surface area is about 125sqft.

 

[addy1]

Welcome to our forum!

Even if small the bog will help. I filter 11 ponds with nothing but a bog, ponds from small to big.