Pond build, Question 1

[GaryMoz]

After a couple of years of thinking we hope to start work on landscaping our garden, we only been here for 20+ years, as part of the landscaping I will be putting a bigger better pond. The current pond is a small raised bed pond, this one will around 10 bigger

It's a bit of hybrid pond using a bottom drain and a bog filter. Over the next few days I want to finalise the design and may have quite few questions.

It's approximate dimensions are 5300 x 3700 and 1250 mm deep, with a volume around 21000 ltrs or around 5500 US gallons
It's walls will be 100mm concrete blocks laid on the side, with a box welded liner, around 1/4 of it will be above ground.

Because I'm using a bottom drain I was advised to use a settlement before the water was pumped to the bog filter, as it was difficult to fit an adequate size tank in, I've decided to go for drum filter to keep maintenance down. (the dirty water from self cleaning will be pumped into near by planting area.

So i will have a skimmer and bottom drain feeding into a drum filter and then the water will be pumped into the bog filter. The bog filter will be loosely based on the aquascape type wetland filter, but using standard building components, soakaway crates, drilled twin wall pipe as caterpillars, inspection chamber for snorkel etc.


So question:

1. Because we wanted a crisp pond with vertical sides, we are going for concrete blocks, with a box welded liner with underlay. Bearing in mind the shape of the pond are there any cost effective alternate methods instead of using the welded box liner?

I will really appreciate any responses.

Thanks

Gary

 

[addy1]

Welcome to the forum!

Great looking design.

I can't help with bottom drains etc..all my pond has is a bog, without snorkels etc. IE very basic, but working since 2010 without issue. No cleaning

@GBBUDD should have some great input, his pond has a lot of what you are using.

 

[GaryMoz]

Welcome to the forum!

Great looking design.

I can't help with bottom drains etc..all my pond has is a bog, without snorkels etc. IE very basic, but working since 2010 without issue. No cleaning

@GBBUDD should have some great input, his pond has a lot of what you are using.

Thanks for the reply.

I many respects I wish I was doing a simpler pond with a shallow bog filter, but when I first came across bog filters, or wetland filters as Aquascape likes to call them, it was the deep type with crate , so I have that set my mind on that.

I have been looking at @GBBUDD posts and he has gave me good feedback. My problem is I overthink everything trying to get a perfect solution for minimal cost, I just need to get on and do it.

 

[GaryMoz]

Decision made, I'm going stick with block and a box liner.

Now to more on for the next set of questions.

 

[addy1]

Mine is 2.5 feet deep, 27 feet long, 4.5 feet wide. Just pea gravel and pvc pipes.

Works great! The snake, frogs. Birds all love it.

 

[GBBUDD]

After a couple of years of thinking we hope to start work on landscaping our garden, we only been here for 20+ years, as part of the landscaping I will be putting a bigger better pond. The current pond is a small raised bed pond, this one will around 10 bigger

It's a bit of hybrid pond using a bottom drain and a bog filter. Over the next few days I want to finalise the design and may have quite few questions.

View attachment 162016View attachment 162018

It's approximate dimensions are 5300 x 3700 and 1250 mm deep, with a volume around 21000 ltrs or around 5500 US gallons
It's walls will be 100mm concrete blocks laid on the side, with a box welded liner, around 1/4 of it will be above ground.

Because I'm using a bottom drain I was advised to use a settlement before the water was pumped to the bog filter, as it was difficult to fit an adequate size tank in, I've decided to go for drum filter to keep maintenance down. (the dirty water from self cleaning will be pumped into near by planting area.

So i will have a skimmer and bottom drain feeding into a drum filter and then the water will be pumped into the bog filter. The bog filter will be loosely based on the aquascape type wetland filter, but using standard building components, soakaway crates, drilled twin wall pipe as caterpillars, inspection chamber for snorkel etc.


So question:

1. Because we wanted a crisp pond with vertical sides, we are going for concrete blocks, with a box welded liner with underlay. Bearing in mind the shape of the pond are there any cost effective alternate methods instead of using the welded box liner?

I will really appreciate any responses.

Thanks

Gary

My first observation is is your skimmer going to have a matala mat or just a basket strainer.
2. Your drum filter is going to require maintenance. Replacing spray jets sensors trouble shooting etc. That area looks very tight.
3. Your water going to the wetland filter is going to be free of anything that would otherwise would start to clog a bog. Don't know if a settling chamber is realy needed. Your rdf is going to do that job plus some. Your preference to do a wetland filter is great but is there going to be a waterfall or stream anywhere? Reason I ask is rdf don't do alot to add O2, wetland filter defiantly do nothing on the contrary they strip the water of O2. With the bacteria using up what's available that is in the water column. Thus there needs to be some measure to add O2 into the water. Is a floating bed of K1 an option. Or is a simple aerator the best solution.

3.So you must be thinking of gravity fed to the rdf , then pump to the bottom of the bog/ wetland filter.? So from the bog how does water get back to the pond? Is the bog going to be higher than the pond by Inches " ? A foot ? Creating a waterfall.

4. how many gph are you leaning toward using.

5. A traditional raised koi pond Luke that in the UK would have at least two main drain would there not . That's a simple and not expensive addition. Here in the states it would acutely be mandatory so no one could get stuck by the suction. They would both need to be on the same drain pipe so as one attempts to be blocked the second full size drain can carry the load of the line.


With block walls if built correctly there are many options when it comes to water proofing. A skim coat of plaster can do the job . Pools have used this for century's. Fiberglass is another solid option , as is are many printable coating. How ever None of them have the bennifits that a welded liner does. A liner like that on a solid surface will be incredibly durable. Impossible to puncture that will cause a leak. Only a slice can create a problem. Regardless of which route you go the block construction will remain the same.
A compacted soil base for footings and your slab. A 1 foot thick footing with 2 pieces of rebar should then be poured.
Cinder block installed correctly, not cinderblocks turned on the side" I don't understand that thinking. " cinderblocks have zero strength on their side. This is why the cinderblocks need to be poured solid once the wall is built.
Once one level is laid out all around the pond. I would then go around and drill in my rebar. Holes into the footing these act as lateral support as cindrblocks weak point is side pressure. These rebar need to run all the way up to the top course but do not need to be in one piece, though is better to do so. You can overlap the rebar this should be at least a foot.
You can use pretty much anything you'd like between the bays of the block byt a wet concrete with a slump of about a 7 will flow well between the bays.

 

[GBBUDD]

Sorry for the late response I am at an aquascapes academy seminar this week.

 

[GaryMoz]

Thanks for your reply, I sure your aquascape conference was good fun , I have put up another post with a few questions with one about skimmers or whether to use a simple intake bay

My first observation is is your skimmer going to have a matala mat or just a basket strainer.

If I don't need the basket and the drum filter can deal with the surface debris then I will stay with the simple drum filter

2. Your drum filter is going to require maintenance. Replacing spray jets sensors trouble shooting etc. That area looks very tight.

Once I know what rdf I'm getting I can adjust the space bit to give better access.

3. Your water going to the wetland filter is going to be free of anything that would otherwise would start to clog a bog. Don't know if a settling chamber is realy needed. You rdf is going to do that job plus some.

By settling chamber do you mean the soakaway crates under the wetland? if so this could change things, I rather not have the RDF, they are expensive and cost a lot to run.

Because I am using bottom drain(s) I was told I should use a settlement chamber, i.e. a separate area before it went into the bog to get rid of all of the worst debris. I thought i didn't really have room for one so reluctantly i decided to use a RDF.

Would the water reservoir underneath the wetland filter count as the settlement chamber? I will have an inspection chamber in which I can drop down a sump pump to clean it out. I would much prefer to take this route and do away with RDF

Your preference to do a wetland filter is great but is there going to be a waterfall or stream anywhere? Reason I ask is rdf don't do alot to add O2 wetland filter defiantly do nothing on the contrary the strip the water of O2. With the bacteria using up what's available that is in the water column.

I have done a change to design to raise the wetland area so there will be a small waterfall, I am also going to use Aerator in the bottom drains

3.So you must be thinking of gravity fed to the rdf , then pump to the bottom of the bog/ wetland filter.? So from the bog how does water get back to the pond? Is the bog going to be higher than the pond by Inches " ? A foot ?

Yes it would be gravity feed, not I'm not sure where pump will be, if it is with RDF it will be easy to get to and easy to plumb gates or divertors to jets. Although I prefer a submersible pump. As mentioned before there will be small waterfall around 8-10", but I will also have Aerators

With block walls if built correctly there are many options when it comes to water proofing. A skim coat of plaster can do the job . Pools have used this for century's. Fiberglass is another solid option , as is are many printable coating. How ever None of them have the bennifits that a welded liner does. A liner like that on a solid surface will be incredibly durable. Impossible to puncture that will cause a leak. Only a slice can create a problem. Regardless of which route you go the block construction will remain the same.
A compacted soil base for footings and your slab. A 1 foot thick footing with 2 pieces of rebar should then be poured.

I have now decided to keep to blocks and box liner? (one decision made )

Cinder block installed correctly, not cinderblocks turned on the side" I don't understand that thinking. " cinderblocks have zero strength on their side. This is why the cinderblocks need to be poured solid once the wall is built.

This may be a missed translation from English to American, for me concrete block is solid, we can get hollow concrete blocks but they're called hollow concrete blocks . I believe a lot of bricklayers prefer to lay 100mm blocks on their side instead of using 200mm because of the ease of handling, 200mm (8”) solid blocks weigh a lot. Th 215mm thickness makes it a lot more ridged. This is pretty much the standard why of doing blocks for ponds in the UK

Once one level is laid out all around the pond. I would then go around and drill in my rebar. Holes into the footing these act as lateral support as cindrblocks weak point is side pressure. These rebar need to run all the way up to the top course but do not need to be in one piece, though is better to do so. You can overlap the rebar this should be at least a foot.
You can use pretty much anything you'd like between the bays of the block byt a wet concrete with a slump of about a 7 will flow well between the bays.

I understand the logic and it makes sense to me, I will discuss it with bricklayer.


Thank you for taking the time to answer my questions

 

[GBBUDD]

If I don't need the basket and the drum filter can deal with the surface debris then I will stay with the simple drum filter

No they"rdf" filters work very pooly actually when it comes to leaves needles algae etc the larger stuff can get caught up in the rotating part of the filter and cause it to bind up or strip. A simple basket strainer is all that's needed.

Once I know what rdf I'm getting I can adjust the space bit to give better access. I personally don't know anyone with one only know what I have read. And just knowing it's a machine a break down is inevitable.

Yes you don't want to take debris and just have it get sucked into a pump and chewed up and spit into a bog with or without a settling chamber. It's inevitable stuff is going to get there as will mulm and it there's a settling area it is allowed to drop out of the water column. I just went through similar thoughts with my own pond while the water is clear can see down 6 feet and across the pond underwater across 25 feet it could use just that little but more. A rdf is king in this regard it takes out solids from 70 to 300 micron depending on what size screen you use. And the rdf can make the water look absolutely polished.
But because of all the moving parts and I am not a mechanic. Tell me what is keeping it from working when it goes down and I can figure out how to replace but that's about it there's no one in my area that can service a rdf. I am installing a micro k1 bead filter to help pull out floating particles. I do not have a skimmer no mechanical pads . So the bead was my depiction. I am a firm believer in over filtration.
They do have basket strainers that are a single pool filter size and then there is the tripple basket if you have lots of leaves and needles.

 

[GBBUDD]

Would the water reservoir underneath the wetland filter count as the settlement chamber

Yes . But you wantvto keep leaves and needles out stuff that can get through a basket strainer is as big as you want.

do away with RDF

Rdf when they work the water can be polished to a point little else can achieve.
From what I have seen that looked impressive was a basket strainer to a rdf and then to a floating bed and then to a baking shower. Or a skimmer with mats and the wetland filter.
It depends how much debris and how heavy a fish load your looking at.

I would lean toward external pumps . If they die the gear oils etc don't get in the water like a submersible will. Also submersible cost more to run

 

[GaryMoz]

Yes . But you wantvto keep leaves and needles out stuff that can get through a basket strainer is as big as you want.
Rdf when they work the water can be polished to a point little else can achieve.
From what I have seen that looked impressive was a basket strainer to a rdf and then to a floating bed and then to a baking shower. Or a skimmer with mats and the wetland filter.
It depends how much debris and how heavy a fish load your looking at.

I would lean toward external pumps . If they die the gear oils etc don't get in the water like a submersible will. Also submersible cost more to run

Ok I think for now I will do away with RDF or at lease replace it with DIY strainer , but leave a space to put it if I need it in the future.

So my thoughts are to put two inwall skimmers, but remove the baskets (i may not be around to empty them enough)

So I will have 4 inlets to the strainer box, this would place so water level would be the same as the pond, so form of massive basket that could be left a few weeks, So I could make something like this, perhaps make two with two inlets each connected to it's own pumps to give more control. The water level is the same as the pond.

Do you think this will work?

 

[GBBUDD]

Anything can work but the whole idea to skimmers is to get what falls into the pond and is inbthe process of getting waterlogged and sinks . To pull it into the skimmer before it has a chance to sink. Thus you want to take from the water's surface.
Now I'm not exactly sure why all skimmers are 8 to 12 inches wide and have a draw of 12 inches by say 2 inches deep. If the opening is 24 inches wide it realy pulls from the surface drawing in anything much faster. So this is my take on skimmers . But I do know your pipe being below the surface is not going to draw from the surface very well. So as far as any design I would want I try to get any step of filtration optimized. Thus a shallow wide intake at the surface.

Off topic but will have a huge impact on efficiency of your pond is to round your corners. Water current will not push into the corners very well but it will round a corner. Yes this can mean a bit of work but again it will optimize design for filtration. My self I would just build the standard box of the pond then place cut block inside the corner and the Pour it With concrete. Spend the extra money on shape and anything in the pond and get your cadalac exccessories outside when the initial sticker price becomes history.

Another consideration you might want to think about is a air line inside the pond. For the winter aerating . An oversize someone I know did . During the winter he has the air line running over the top of the pond and it drives him NUTS.

 

[GBBUDD]

I like the rounded wall but how are you planning to build this ? The first question is how far above ground is the pond go to be? If you have earth behind the wall rebar is no longer crucial but it is a good insurance policy. So yes rebar goes with Hollow block. The round will cost double the amount of time and money as each block is either cut on both sides on an angle or just on one side.
Any mason who can construct that will have no issue rounding the corners but will be an issue for the welded box I would think. But even if the corners were 45 degree angles that will help greatly with circulation.

Sitting at the airport I'm glad you have asked questions gives me something to do.

 

[GBBUDD]

As to skimmers there is a company here in the states Helix " the pond digger" who has a basket that is the size of three skimmer pool baskets in height. If you had two of those even in the fall you'd have little to worry about.
One trick I did do when I was traveling and worried about the same. I would place 1.5 inch pvc caped infront of the skimmer this way it was floating. It held back the majority of the leaves and the skimmer remained functioning

 

[GaryMoz]

Anything can work but the whole idea to skimmers is to get what falls into the pond and is inbthe process of getting waterlogged and sinks . To pull it into the skimmer before it has a chance to sink. Thus you want to take from the water's surface.
Now I'm not exactly sure why all skimmers are 8 to 12 inches wide and have a draw of 12 inches by say 2 inches deep. If the opening is 24 inches wide it realy pulls from the surface drawing in anything much faster. So this is my take on skimmers . But I do know your pipe being below the surface is not going to draw from the surface very well. So as far as any design I would want I try to get any step of filtration optimized. Thus a shallow wide intake at the surface.

I'm not sure if I made it clear, but I do intend to have two shallow wide mouth surface skimmers which will be connected to the "strainer box" as well as the bottom drains, this will strain off all the big stuff before going to the pump and settlement area under the bog. Or at least that's the idea i have