Advise: New Concrete Koi Pond with Wetland Filter


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Hi there!

I'm new to this, and would love to get suggestions and tips regarding this newly planned concrete Koi pond with wetland filtration system.
My goal is to have superior water quality with healthy fish and low maintenance (as much as possible).

The pond net area is 94.2 square foot, and the wetland filter net area is 67.8 square foot (attaching 3D simulations and real site photos of the construction).
There's also a pump area (as can be seen in the attached sketch in green).
There are two 2'' flexi-pipes coming from the bottom of the pond area (embedded within the pond concrete floor), going to the pump area.
The longer pipe is ~350 inches long and the shorter pipe is ~205 inches long.
The pond and wetland-filter areas are 3 foot deep and the pump area is 4.9 foot deep.

I'm planning to install one skimmer (probably the Helix) and prefer all pumps to be external (rather than submersible) and located inside the pump area (if possible).
Also, I'm planning to install a long Centipede module at the bottom of the wetland filter with AquaBlox covering it and then stones (large => medium => small).
The water from the skimmer should feed the Centipede module at the bottom of the wetland filter (probably with a UV light sterilizer before the wetland filter), and then back into the pond through a small waterfall.

I would love to hear your suggestions and tips - specifically on the following:
1. How do you think I should use the two flexi-pipes?
a. Maybe as 2 jets? (if so how should I feed these jets)
b. Maybe in a loop - one (as pond intake) connected through a pump to the other (back to the pond)?
c. Maybe the two pipes should feed the top of the wetland filter with water from the bottom of the pond?
d. Maybe they should push air/oxygen to the pond somehow?
2. Do you think I will need 2 additional holes in the pond area (in two opposite ends) to connect pipes in order to circulate the water around the pond?
3. What type of pumps should I use?
4. Other important considerations/ideas?

Thank you very much for your assistance!
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All images and measures are also available here: https://shmoolik4.wixsite.com/lotus


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addy1

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Welcome to the forum! Will read your plans better later, heading out to work in the yard
 
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That is going to be amazing. I don't see any obvious problems but you'll have to be on top of keeping the drains cleared of debris. You might negate this by covering them with a milk crate covered with some coarse filter mat to act as a screen to catch things before it clogs them.
 
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That is going to be amazing. I don't see any obvious problems but you'll have to be on top of keeping the drains cleared of debris. You might negate this by covering them with a milk crate covered with some coarse filter mat to act as a screen to catch things before it clogs them.
Thanks! Regarding the drains, I was thinking of putting two of these: https://sacramentokoi.com/advantage-drain-cover-with-air-diffuser/.
This should also give me some aeration for the Koi.
Also, I was thinking of putting a pressure filter for pre-filtering the solids coming from the two drains prior to the wetland filter (so that the wetland will not clog too soon - -what do you think?
 
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Thanks! Regarding the drains, I was thinking of putting two of these: https://sacramentokoi.com/advantage-drain-cover-with-air-diffuser/.
This should also give me some aeration for the Koi.
Also, I was thinking of putting a pressure filter for pre-filtering the solids coming from the two drains prior to the wetland filter (so that the wetland will not clog too soon - -what do you think?
I've never seen anything like that before, but if it works as designed, seems like a good solution. Aeration is good and you need to keep your drains clear, seems like a win/win. I would definitely put some sort of prefilter in line to catch big things before they get to your pumps' impeller, but you do not want your bog being starved by putting a pressure filter with mechanical filtration you plan to clean out in front of it, I don't think. A strainer or prefilter you can easily pull a basket out of and dump, yes. A full filter that is going to starve your bog of nutrients, no.
 
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If your bog is sized and built correctly, you won't need any additional pressure filter. And as stated, it might actually be a hindrance to the functioning of the bog.

Plus, you said you were looking for as little maintenance as possible and a bog fits that bill. Rinsing filter pads from a pressure filter gets old real fast. It takes the fun out of the enjoyment of a pond.

To give you an idea of what I experienced...
My pond is about 1800 gallons and it has gotten way overpopulated over the years. This eventually caused my water to be constantly green from algae. I had two pressure filters running and one had a UV light. The water was solid green. I was constantly cleaning out those filters and still had green water even with a decent amount of plants.

I built the simple type bog with PVC manifolds under the gravel. No snorkel, centipede or Aqua Blox.

My bog surface area is a little over 30% of my pond surface area. My water is crystal clear with practically zero maintenance.

You also mentioned something about having the water pour on top of the bog. That's a bad idea. Sludge will eventually build up on top of the gravel and it will be a mess. The water should be distributed underneath the gravel and rise up through the gravel.
 
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Very cool project. Look forward to following. Your A/C condensate line dumping into the wetland probably won't produce enough to be a problem, but do keep in mind that condensate water tends to be very acidic.
 
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One issue i see is your drains are independent and they need to be tied in together . this is code in Many places so that if someone was to get on the drain it would not hold them in place that the second drain will allow for the suction to have somewhere to pull water in and not hold someone underwater. particularly since this is apparently your front entrance if someone was to fall in and sooner or latter someone will. the other thing is one drain has to be large enough to allow for the complete draw of the pump or for a 2" line is only 4,000 gph .

Second observation is a lot or right angles this will trap and reduce any attempts of creating circulation requiring more energy to do the same job as if you had rounded corners. Now i understand contemporary and right angles but you can leave the square corners above water and simply round them below the water where it will be harder to see.

I assume your going with plaster to water proof ?

I would design the pond so that you have water pushing is a circular rotation even though your not round. Put a pump against the house pushing on an angle toward the yard and the wall against the yard have a pump pushing toward your planter. and a third pump back of the planter toward the bog pushing toward the first pump. this will help keep things moving and working toward the skimmer and the center where the water is kinda in a limbo is where you already have your main drains.

I would also have a small amount of water dropping out from the planter just a small trickle adding some interest and life to that area.

It looks like your wetland spill way is the same height as is your island? Rule of thumb is wetland walls be about 6" min higher then the water level so that the plants do not pull the water up and over the walls and trust me they can do so easily defying gravity
 
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I've never seen anything like that before, but if it works as designed, seems like a good solution. Aeration is good and you need to keep your drains clear, seems like a win/win. I would definitely put some sort of prefilter in line to catch big things before they get to your pumps' impeller, but you do not want your bog being starved by putting a pressure filter with mechanical filtration you plan to clean out in front of it, I don't think. A strainer or prefilter you can easily pull a basket out of and dump, yes. A full filter that is going to starve your bog of nutrients, no.
Thank you very much for your comments and suggestions!

Looking at the line coming from the pond side skimmer, this line is going to feed the wetland.
The water is drawn from the top of the pond feeding the centipede module at the bottom of the wetland.
For my pond and wetland sizes, I was thinking of going for a 2000 GPH external pump (maybe this one).

I see your point regarding starving the bog filter and surely I don't want to do that.
However, I do need to take care of solids and sediments that otherwise can clog my bog filter fast.
I know the skimmer basket takes care of some of it, but I guess it will not be enough.

How do you suggest I take care of the large sediments and solids prior to the bog filter while keeping enough nutrients for the wetland?
 
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If your bog is sized and built correctly, you won't need any additional pressure filter. And as stated, it might actually be a hindrance to the functioning of the bog.

Plus, you said you were looking for as little maintenance as possible and a bog fits that bill. Rinsing filter pads from a pressure filter gets old real fast. It takes the fun out of the enjoyment of a pond.

To give you an idea of what I experienced...
My pond is about 1800 gallons and it has gotten way overpopulated over the years. This eventually caused my water to be constantly green from algae. I had two pressure filters running and one had a UV light. The water was solid green. I was constantly cleaning out those filters and still had green water even with a decent amount of plants.

I built the simple type bog with PVC manifolds under the gravel. No snorkel, centipede or Aqua Blox.

My bog surface area is a little over 30% of my pond surface area. My water is crystal clear with practically zero maintenance.

You also mentioned something about having the water pour on top of the bog. That's a bad idea. Sludge will eventually build up on top of the gravel and it will be a mess. The water should be distributed underneath the gravel and rise up through the gravel.
Thank you very much for your comments and suggestions!

When you say you have zero maintenance can you be more specific?
How often do you clean your wetland? Once a year perhaps (at least that's what I read for a good amount of maintenance)?

Looking at the line coming from the pond side skimmer, this line is going to feed the wetland.
The water is drawn from the top of the pond feeding the centipede module at the bottom of the wetland.
For my pond and wetland sizes, I was thinking of going for a 2000 GPH external pump (maybe this one).

I see your point regarding starving the bog filter and surely I don't want to do that.
However, I do need to take care of solids and sediments that otherwise can clog my bog filter fast.
I know the skimmer basket takes care of some of it, but I guess it will not be enough.

How do you suggest I take care of the large sediments and solids prior to the bog filter while keeping enough nutrients for the wetland?

Concerning the water that I plan to pour on top of the wetland.
Since this is a Koi pond I must take care of solids (fish poop) that are accumulated on the pond bottom.
As you probably saw, I have 2 bottom drains for that. Two 2'' flexi-pipes will draw water from these drains to the pump area.
The speed in which the water is drawn from these bottom drains is way to fast for a bog filter.
Now, the question is - what do I do with the dirty water from the drains.
I was planning to filter them using a different method pressure filter / sieve / gravity fed.
What do you think?
 
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Very cool project. Look forward to following. Your A/C condensate line dumping into the wetland probably won't produce enough to be a problem, but do keep in mind that condensate water tends to be very acidic.
Thanks, I will take that into consideration - even though the amount of water is negligible.
 
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One issue i see is your drains are independent and they need to be tied in together . this is code in Many places so that if someone was to get on the drain it would not hold them in place that the second drain will allow for the suction to have somewhere to pull water in and not hold someone underwater. particularly since this is apparently your front entrance if someone was to fall in and sooner or latter someone will. the other thing is one drain has to be large enough to allow for the complete draw of the pump or for a 2" line is only 4,000 gph .

Second observation is a lot or right angles this will trap and reduce any attempts of creating circulation requiring more energy to do the same job as if you had rounded corners. Now i understand contemporary and right angles but you can leave the square corners above water and simply round them below the water where it will be harder to see.

I assume your going with plaster to water proof ?

I would design the pond so that you have water pushing is a circular rotation even though your not round. Put a pump against the house pushing on an angle toward the yard and the wall against the yard have a pump pushing toward your planter. and a third pump back of the planter toward the bog pushing toward the first pump. this will help keep things moving and working toward the skimmer and the center where the water is kinda in a limbo is where you already have your main drains.

I would also have a small amount of water dropping out from the planter just a small trickle adding some interest and life to that area.

It looks like your wetland spill way is the same height as is your island? Rule of thumb is wetland walls be about 6" min higher then the water level so that the plants do not pull the water up and over the walls and trust me they can do so easily defying gravity
Thank you very much for your comments and suggestion!

Regarding the bottom drains - they don't necessarily need to be tied together - I can use 2 pumps for each drain if I choose to - and I understand that you think this is the preferred way to go, right?

Regarding the proofing - I am planning to use this product which I have good experience with.

Regarding water circulation - yes - I am planning to take care of this and I understand right angles are not optimal :sneaky:

Regarding the waterfall coming from the wetland, I do plan to keep ~6'' of height to the pond water level.

Also, from your experience - and considering my basic design - what would you do with the 2 flexi-pipes coming from the bottom drains of the Koi pond? These pipes (covered with these) should draw solids and sediments and I cannot feed the bottom of the wetland with them.
 
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Regarding the bottom drains - they don't necessarily need to be tied together - I can use 2 pumps for each drain if I choose to - and I understand that you think this is the preferred way to go, right?
I have no idea what building codes are in Israel . but here in the states when a water body has a drain once it gets deeper then X there has to be two drains on the same pipe each that can intake the full suction of the pump . so if your pump is a 4000 gph then your drains BOTH need to be able to handle 4000 gph each that way if someone did plug one up while being underwater the other drain will be able to handle the suction and not hold someone under water and drown.
Regarding the proofing - I am planning to use this product which I have good experience with.
This statement makes me question if its safe for fish I got it off a different site your link wanted me to except cookies. my cookies are mine. no offence.
{"Repair of flat roof waterproofing on roofs of structures which are not habitations}
I would look at plaster its been used for hundreds of years . though i know there are many man made today that will work
Also, from your experience - and considering my basic design - what would you do with the 2 flexi-pipes coming from the bottom drains of the Koi pond? These pipes (covered with these) should draw solids and sediments and I cannot feed the bottom of the wetland with them.
But you can and should . i would have the two 2 inch lines tie together with a 3 inch tee-y This will not restrict the water flow from either line. If your using a pump larger then 4000 gph if under 4000 then a 2 inch tee-y or 2 1/2 " tee y would suffice. from the tee-y i would run that right to your external pump that has a strainer basket. and that will keep any solids from getting to the pump and lock it up . The water front he pump depending on the size you go with can then be pumped to the bottom of the bog/ wetland filter . and or be split and have the pump push some of the water right back to the pond for circulation. i would have the water fall come out more in the left corner from where you have it facing the steps and front door. im assuming this is the from entrance to the home. this way you can see it as you walk up to the door and the current will push the water across toward the walkway over the pond the x in yellow are pumps or return jets and red is direction of flow . at least this is how i would set it up this way you have all the corners covered and the drains in the center are in your dead spots and will draw the dirt in
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Thank you very much for your comments and suggestions!

Looking at the line coming from the pond side skimmer, this line is going to feed the wetland.
The water is drawn from the top of the pond feeding the centipede module at the bottom of the wetland.
For my pond and wetland sizes, I was thinking of going for a 2000 GPH external pump (maybe this one).

I see your point regarding starving the bog filter and surely I don't want to do that.
However, I do need to take care of solids and sediments that otherwise can clog my bog filter fast.
I know the skimmer basket takes care of some of it, but I guess it will not be enough.

How do you suggest I take care of the large sediments and solids prior to the bog filter while keeping enough nutrients for the wetland?
A prefilter basket catches all the large solids and allows you to remove them without starving your bog of nutrients:
https://koimarket.com/shop/pond-supplies/pond-filters/bead-filter/gctek/aquasieve-2-pond-prefilter/
https://russellwatergardens.com/products/pond-sieve-hydrosieve
 
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This statement makes me question if its safe for fish I got it off a different site your link wanted me to except cookies.
Nice catch - thanks! Actually I was using this product for a different application (just water no aquatic life) and it was very good so I assumed it'll fit. But you are absolutely correct and this product is not safe foe aquatic life so I will need to find an alternative. Shouldn't be hard. Thanks again for bringing it to my attention!

But you can and should . i would have the two 2 inch lines tie together with a 3 inch tee-y This will not restrict the water flow from either line. If your using a pump larger then 4000 gph if under 4000 then a 2 inch tee-y or 2 1/2 " tee y would suffice. from the tee-y i would run that right to your external pump that has a strainer basket. and that will keep any solids from getting to the pump and lock it up . The water front he pump depending on the size you go with can then be pumped to the bottom of the bog/ wetland filter . and or be split and have the pump push some of the water right back to the pond for circulation.
I have 3 pipes:
1. Bottom drain 1
2. Bottom drain 2
3. From pond side skimmer (Helix)

If I connect all 3 pipes to the bottom of the bog filter, I will need too strong a pump which will harm the biological filtration.
I am planning to feed the bog with a maximum of 3000 GPH (from the skimmer).
As you suggested, I can (and will) use a split.
However, instead of directly pushing water to the pond, and since the water coming from the bog filter aren't strong enough to create good water flow on the waterfall between the bog and the pond, I am planning to slowly pour highly oxygenated clean water over the bog filter.

i would have the water fall come out more in the left corner from where you have it facing the steps and front door. im assuming this is the from entrance to the home. this way you can see it as you walk up to the door and the current will push the water across toward the walkway over the pond the x in yellow are pumps or return jets and red is direction of flow . at least this is how i would set it up this way you have all the corners covered and the drains in the center are in your dead spots and will draw the dirt in
The jets is a great idea and I was already thinking about it and read about recommended heights and equipment - thanks!
Regarding the waterfall location - from technical reasons I cannot move it at this stage.

Wow!!! I must say that your pond is one of the most beautiful pieces of heaven I have ever seen!
Absolutely amazing!
Thank you for your time and all your tips - they are very valuable!
 
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If I connect all 3 pipes to the bottom of the bog filter, I will need too strong a pump which will harm the biological filtration.
I am planning to feed the bog with a maximum of 3000 GPH (from the skimmer).
As you suggested, I can (and will) use a split.
However, instead of directly pushing water to the pond, and since the water coming from the bog filter aren't strong enough to create good water flow on the waterfall between the bog and the pond, I am planning to slowly pour highly oxygenated clean water over the bog filter.
2 points; first is that if you 'pour water over the bog filter' you're not doing much good re filtration as a bog filter (more properly upflow wetland filter) works by forcing water UP through the pea gravel. Pouring it on top defeats any benefit as the water isn't forced to do anything but find an egress, which of on top, not through anything.

Second point; generally, bog filtration works best with a SLOW flow-through, hence you don't need huge amounts of water/force with this system. Some (including me) put much more and still get good results, so you've got plenty of leeway.

That said, you can push water to the bottom of your bog AND pour some overtop to get the look you want re waterfall action. Just be aware that over time, the water height in your bog will rise, so have enough liner wall height above normal water height when this happens or it may overflow where you don't want it.
 
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