Will this homemade pond filter design work?

[Hop-frog]

I am building a pond with the following shape, measuring about 40 ft across. The wall is there to keep out mud from flash floods. It is made of brick, but has a reinforced metal frame to hold the actual liner, so there's a small working space between the liner and brick wall to run pond lights and future upgrades. The pond water doesn't actually press against the brick, there is a 2" hidden gap. The center 6 ft. The outer ring is almost 2 ft deep, so providing safety for children and stability to the ground under the wall.

I will install a 4" pipe like so (see yellow pipe), with the top a water level, in case heavy rainstorms dump too much water in the pond. This causes the water to be redirected to a safe place, instead of spilling over the sides and flooding the yard, as we do get monsoons that can dump massive amounts of water. The 4" pipe size might not even be sufficient give the rate of rainfall here...

For filtration, I plan to carve out an area that is somewhat within reach in the shallow area just over the wall. The liner will lay in this area, filter equipment above it, then buried under river rock, so as to hide it completely. In the picture above, it is the rectangular cut-out area.

The pump is of homemade design. The red pipe represents where water goes in, thought that might be just a grill hidden under river rocks. The water passes through three large trash cans, exits through a pipe, that possible will snake all around the pool and exit near the rim, to push the whole of the water in a large circle. I wasn't able to illustrate the flexible pipe, but you can see the exit of the pipe in the left of the drawing, just under the water. It points in a manner that would cause the water to circulate counter-clockwise, at least in theory. This worked on tests in a round 3,000 gallon swimming pool, but because this size is larger, I don't know if there will still be good circulation.

For a close up of the homemade filter design see above.

a. Water enters the first submerged trash can. I think the top could be a vent covered in river rocks, but I don't know if that will disrupt the flow too much.
b. The first trash can contains pumice.
c. The second trash can can contain filter floss.
d. The third trash can holds the 4000 gph pump.
e. PVC connects the three trash cans.

The whole design is buried under river rock.

Do you think this design can work?
Any suggestions for improvements? Any suggestions for how to make the filter more easily accessible?

 

[brokensword]

View attachment 135456


I am building a pond with the following shape, measuring about 40 ft across. The wall is there to keep out mud from flash floods. It is made of brick, but has a reinforced metal frame to hold the actual liner, so there's a small working space between the liner and brick wall to run pond lights and future upgrades. The pond water doesn't actually press against the brick, there is a 2" hidden gap. The center 6 ft. The outer ring is almost 2 ft deep, so providing safety for children and stability to the ground under the wall.


View attachment 135459


I will install a 4" pipe like so (see yellow pipe), with the top a water level, in case heavy rainstorms dump too much water in the pond. This causes the water to be redirected to a safe place, instead of spilling over the sides and flooding the yard, as we do get monsoons that can dump massive amounts of water. The 4" pipe size might not even be sufficient give the rate of rainfall here...

View attachment 135457
For filtration, I plan to carve out an area that is somewhat within reach in the shallow area just over the wall. The liner will lay in this area, filter equipment above it, then buried under river rock, so as to hide it completely. In the picture above, it is the rectangular cut-out area.
View attachment 135458

The pump is of homemade design. The red pipe represents where water goes in, thought that might be just a grill hidden under river rocks. The water passes through three large trash cans, exits through a pipe, that possible will snake all around the pool and exit near the rim, to push the whole of the water in a large circle. I wasn't able to illustrate the flexible pipe, but you can see the exit of the pipe in the left of the drawing, just under the water. It points in a manner that would cause the water to circulate counter-clockwise, at least in theory. This worked on tests in a round 3,000 gallon swimming pool, but because this size is larger, I don't know if there will still be good circulation.

View attachment 135460
For a close up of the homemade filter design see above.

a. Water enters the first submerged trash can. I think the top could be a vent covered in river rocks, but I don't know if that will disrupt the flow too much.
b. The first trash can contains pumice.
c. The second trash can can contain filter floss.
d. The third trash can holds the 4000 gph pump.
e. PVC connects the three trash cans.

The whole design is buried under river rock.

Do you think this design can work?
Any suggestions for improvements? Any suggestions for how to make the filter more easily accessible?

I suppose in theory but what a PITA to ever access/maintain. Your filter floss is going to get clogged. Personally, I'd never bury any filter as if access is limited, you're not going to maintain regular maintenance for long. Why not keep all your filtration OUTSIDE the pond? You can shield it in numerous ways and easier.

Also, if you haven't, consider bog (upflow wetland filtration) filtration; there's a lot of advantages. Look on this site for the numerous bog build threads and see if it's something you might like. The maintenance is almost negligible.

Also, make sure you put some sort of screen over that overflow pipe if you don't want any fish/inhabitants to enter during your flash floods.

Another point; it's better/easier to push water through your media than to pull it. I'd reverse your order as you have it should you continue down this road. Your pump will thank you later.

 

[TheFishGuy]

I agree with @brokensword, seems kind of complicated for a fairly simple task.

Upflow wetland, or even just do something like you were describing but outside the pond, easier maintenance, and you aren't having to pile rocks on top of it to hide it.

 

[Hop-frog]

My reason for burying it, is it keeps everything inside the pond, so as to reduce the chance of leaks. With this design, every component stays within the pond liner. If I made this homemade thing outside, I think there is a risk it could break, and at 4000 gph, that would create a backyard flood. I see your point, especially in the winter I wouldn't want to wade into the pond for maintenance...that would be horrible.

I was looking at petstore-sold pond filters for my size pond, and they are way beyond my budget. They can be close to $2000 and still aren't big enough to support a 4000 gph pump. Are there some cheap filters that I can drop my pump inside sufficient for 30k+ gallons of water? Or some product that is ready-made plastic that I can put my own lava rock, pump, filter in, without being costly?

 

[brokensword]

if you plan ahead such that your liner includes the bog, which will be adjacent to your pond, you'll achieve the same thing re 'keeping all in the pond'. It's what I did. You can use a submersible pump, run your line(s) all inside the pond, come up over your pond/bog wall, and then into the bottom of your bog. All pipes then are inside your pond. The overflow from your bog then goes directly back into your pond. And the best part? No maintenance once established, other than thinning the bog plants. The gravel provides you with your bio filter and the plants that grow there help take up the nitrates, all crushing free floating algae's attempt to get a foothold.

Figure out what a bog would cost and see if the number is amenable. Especially in the long run.

 

[Hop-frog]

For a bog, does the pump and input go underground, under the bog, and a little fountain appear at the top? Or can I put the input somewhere else in the pond, and run the output of the pump through a long pipe, to go under the bog?

I have a a smaller 400 gph pump, would that be better for the bog, and use the 4000 gph to make sure the water is flowing fast, giving the fish current? Note the pond itself is more than 30k gallons, but I will be kind of the fish and keep the quantity low.

 

[Mmathis]

So...the entire system is underwater? How are you going to get to it for maintenance and cleaning? Filters and filter media usually have to be cleaned on a regular basis (depending on fish load). Filter floss isn going to lend itself well to pond use. It will clog too easily and have to be cleaned/changed frequently. Have you seen this design before, or are you trying to come up with something original? I understand your desire to prevent leaks, but sometimes convenience has priority over practical. The only way you will know for sure is to build it. BTW, a bog would be just as efficient and requires very little maintenance.

 

[Hop-frog]

This design is based on a homemade pond design I saw online, and also based on an actual aquarium filter I use, it seems to work on the same principal. I'm not trying to do anything new, just trying not to have to pay a bunch of money for a filter, but maybe I found poor advice in YouTube. I will try to figure out how to design a bog.

 

[Jhn]

Just add a Second wall like 3’ outside your pond wall and a bit taller, or can create a berm 3’ inside the entire edge of the wall the bog would be between the berm and the wall, you can add rock on the berm to hide the liner. Then can create a manifold out of 2” pvc schedule 40 pipe, cut slots in it, this lays at the bottom of the bog your pump output line feeds into this pipe, then the water is pushed up through the gravel and dumps back into the main pond. Plant psome plants in the gravel and let them do their job ie filter your water.This would enable you to keep everything inside the pond liners to prevent leaks, if you so choose. Although, will say have had lines outside of my ponds for over 25 years with no major leak issues.

 

[GBBUDD]

You can go on you tube and find video after video on batting beads and bio balls and how eventually they give up trying to get clear water and they switch to a bog or a nexus system. And to have the dirty filter under water and try to lift it up and remove soaked dirty filters or to back wash. I may not see the benefit to the madness but to me it's more work then i'd care to look at heres just one large pond where they did it with a bog and you can't beat it if you spent 50 grand on the best mechanical filter.

I should add i am a first time pond builder and my water has been crystal clear for 3 years now you can see a penny at the bottom of a 6 foot deep pond loaded with stone . you can see my build in the blue link below each of my posts SAVE YOU SOME LEG WORK IF I CAN BUILD IT TO THIS EXTENT ANYONE CAN

Going for it! phase one 12,000 gallon pond.

Which model of Helix Skimmer are you using? Is it the floating weir model? Thanks in advance. No it i not,it is the stationary

www.gardenpondforum.com

 

[Hop-frog]

Okay, I have made changes to the design to try and include a bog filter.

The light green area is a slope, part of which already exists, but will be built larger using the the dirt from the deep area (C).

The bog area is B. It is lined with bricks and metal retaining materials. It shares the same liner as the rest of the pond. I will attempt to conceil it within the artificial hill.

The 4000 gph pump input is placed at A and output under the bog B.

The pump output leads into a network of PVC pipes buried underground, as shown here (Patio Pond with Bog Filter | Bog Filter Construction - Part 2), though I'll use 4" PVC forming a 8 ft x 8 ft grid underground.

Note that the water will be filled to 1" of the brim of the walls.

How does water move from the bog into the pond? Does it need a wall there? Some kind of mesh? Pipes?

 

[GBBUDD]

If you haven't checked out you tube and the thousands of pond builds thats is where i would start . I understand the desire for high sides and a monsoon buttttttttt sides that high destroy a sitting area looking across the pond . now it's hard to say not seeing actual pictures as to what your working with or where you are. it only takes a small mound to deflect water away from your pond . theres nothing like your pond right up to the patio and you can watch the waterfall the fish and the dragon flies etc

 

[brokensword]

Okay, I have made changes to the design to try and include a bog filter.

View attachment 135480
The light green area is a slope, part of which already exists, but will be built larger using the the dirt from the deep area (C).

The bog area is B. It is lined with bricks and metal retaining materials. It shares the same liner as the rest of the pond. I will attempt to conceil it within the artificial hill.

The 4000 gph pump input is placed at A and output under the bog B.

The pump output leads into a network of PVC pipes buried underground, as shown here (Patio Pond with Bog Filter | Bog Filter Construction - Part 2), though I'll use 4" PVC forming a 8 ft x 8 ft grid underground.

View attachment 135481

Note that the water will be filled to 1" of the brim of the walls.

How does water move from the bog into the pond? Does it need a wall there? Some kind of mesh? Pipes?

have your bog be actually higher than your pond. What I did was to use ground-contact pressure treated 4x4 to build a box, which is higher than the pond water level. I made mine 3' deep--2' below pond level and 1' above. Then I placed my liner into the bog, over the adjacent wall, and then into the pond proper. This way, it's all one liner and since the bog is higher than the pond, the water cascades back. I made a deco wall of stone as facia ON the liner and in front of the bog wall, on a shelf I dug prior to lining everything. So, my bog is below ground and above the pond. I placed edge rocks across the top of the adjacent wall and filled the bog with various sized stone, ending with pea gravel, which comes up to the edge stone. By leaving gaps, when the water rises and heads toward the pond, it channels into these gaps and I have a few small mini falls, along with whatever leaks under the edge stone to cascade down the deco rock wall.

This allows you to keep all the plumbing inside the liner; I only had to buy a fake rock to cover where my pump hose rises out of the pond and connects to my bog manifolds (I have two 4" manifolds in my bog as i have 2 pumps). You could also bury the inlet pipe to your bog beneath some pea gravel and have only its entry point to 'cover'/camoflage.

So to sum up; raise your bog higher (like at least 6") than your pond. Fill the bog up, leaving extra liner to compensate for any channeling/rising water (at least 6"), and create some sort of output from your bog to let the rising water fall back to the pond. You can do as I did or fit pipes in. I believe @addy1 cut slots in her bog (similar to what I did with stone) and water exits that way.

 

[GBBUDD]

Agree with the above with one small differance the minimum 6" i would make 18" then you can make a nice waterfall or dropping stream i built my bog up 7 feet leaving me with only a 12" drop at the time that was a lot to build p the back of the yard with mafia blocks and lumber. but in the scale of things the extra weekends worth of work and the extra 1000 bucks would have made a heck of a difference for decades

 

[Hop-frog]

What dimensions am I looking at needing for this bog to support the pond? I have minimal space remaining, but there is kind of a 10x15 ft space in the corner, and then a 3x20 ft space between the pond and fence that could be used.

To support the 30k+ gallon size, which dimensions are most important to consider? Does the bog filter need more depth? Surface area? Volume? Will the 4000 gph flow rate through it be too fast for it to function properly, or will a larger size of bog counteract that?

 

[GBBUDD]

first of all 4000 gph in a 30,000 gallon pound is like a flea on a saint bernard. it may sound like a lot but the rule is to turn over a pond 1 to 1.5 times and hour . Now when you do get to a larger pond that number can be reduced as you have a lot more volume .and space for nitrafying bacteria to grow and is harder to to pollute. I am about half your pond size and i have a 10 x18 aqua block bog pushing 12,000 gph Heres a huge pond build but it is easier to see the processes

 

[brokensword]

What dimensions am I looking at needing for this bog to support the pond? I have minimal space remaining, but there is kind of a 10x15 ft space in the corner, and then a 3x20 ft space between the pond and fence that could be used.

To support the 30k+ gallon size, which dimensions are most important to consider? Does the bog filter need more depth? Surface area? Volume? Will the 4000 gph flow rate through it be too fast for it to function properly, or will a larger size of bog counteract that?

surface area is what you're looking at; typically, 30% of the pond's surface area should be your target. Depth should be minimal at 12" of 3/8 pea gravel. You can go deeper. Typically, most don't but this is what I did; 12" of large round stone followed by 12" of 2" cobble stone and then 12" of pea gravel. Your pipe manifold(s) lays beneath all of this, in a trench and pitched to a low point for any cleanout purposes. My bog is roughly 20' x 3' x 3' depth. And I ONLY have 7k gallons in my pond. So, you see you should try for as much as you can get but if you don't plan on heavy stocking, you can do with less. Volume in your bog can be advantageous too as the more volume, the more pea gravel surface for your good bacteria to colonize, which is the main point of a bog. That and the plants you place on top.

And don't pull water from the pond bottom but instead, higher up; your bog will thank you.

I'd suggest you have more than one pump in case one fails. Treat the bog as supplemental. I have 2 pumps and each has a tee on it; I send one part to a water fall and one to the bog. So I probably have 4K gallons per hour, give or take, being sent to my bog. Slower tends to be better re bog filtration so you don't need a huge amount of flow/gallons. You're working with a lot larger pond, so you may have to start and add if necessary. If you lean this way, provide a few bog inlets to manifolds down below, to future proof. Look at the various bog building threads here to familiarize yourself and see if such an idea is beneficial for you.

 

[Hop-frog]

Can the bog function backwards? I mean...pump water from under the bog into the main pond, and a waterfall returns water back into the bog? The reason I ask, is I have limited remaining space for an elevated bog...really struggling to figure out where to put it in the design.

 

[brokensword]

Can the bog function backwards? I mean...pump water from under the bog into the main pond, and a waterfall returns water back into the bog? The reason I ask, is I have limited remaining space for an elevated bog...really struggling to figure out where to put it in the design.

not nearly as effective if at all; if you 'pour' water onto the top of your bog and wait for it to trickle down where the pump below pulls it down and then pushes it to your pond, you'll find the top of your bog will clog quickly and water will find ways out of your bog. Forcing water to the bottom and letting it rises naturally is the way to do it. If you have any room at all, you can create a box higher walled than your pond. Fit the liner inside as part of the whole piece. This ties both together. You route your pipe from your submersible pump in the pond to over the top and down into your bog. Cover with pea gravel, etc. The return then is gravity, which works well to also help aerate your pond. Win win.

Doing it your way will also increase wear and tear on your pump, which now is at the bottom of your bog, and also, what if you have to maintain the pump? Digging out gravel isn't fun--trust me, I've done it twice.

The way I've outline is proven and works well. Just figure out how to elevate the bog walls higher than your pond and include the necessary liner as part of your overall pond liner cost.

 

[Hop-frog]

Okay, here is my adjusted design, making room for a large bog that also serves to create six 4" high waterfalls, and hopefully some interest effects with water rushing through the rocks in the stairway-like areas.

The vertical dimension is exaggerated in this illustration.

Orange = brick wall, with metal reinforcement
Grey = bog
Blue = water level in main pond

Basically the bog ends up taking up space within the pond itself. The pond liner is laid inside and the inner walls built on top of the pond liner, creating 5 chambers (the back large is one, then two smaller ones on each side). I'm not sure if that is feasible, as usually I put water in the pond liner immediately, otherwise the wind will take it away...it is big enough to completely cover someone's house.

The back elevated part is already on a hill, with this staircase-like design, the pond wall somewhat matches the incline of the slope of the group (in 40 ft it rises 20").

Unfortunately this design seems to nearly double the cost of the pond, between bricks, aquablocks, and probably 5-10 tons of rock needed.