2 Types of DIY Bog filters - 12 inches of pea gravel or 3 foot of large medium small rocks?

[GaryMoz]

I do have a PAIRon the same pipe of bottom drains and I'd not do without them on a larger pond..
I do have a standard basket strainer just like a pool pump has it catches leaves and larger stuff string algae in the beginning.. I can tell when it's time to empy it as the water flow will lesson over the falls. But to empty it you shut the pump off 1/4 turn on the lid opens the strainer I have a compound bucket . I tip the strainer over the bucket . Maybe re.ove a stuck leafe . Throw it back in 1/4 turn the cover flip the switch on. It took as long to type this out on my phone as it does to do it . If your going deeper than 3 feet and wider than 12 I recommend a main drain

Hey, I've just had a quick look at your pond, it looks great.

I would love to know how it is working out using a bottom drain and skimmer, It's what I intend to do but a few people have suggested it's not a good idea.

It will great to hear any advice

 

[GBBUDD]

The ONLY disadvantages to a bottom drain are as follows.
1. YOu realy need two so if a child is underwater and gets to close that they don't get caught in the suction and held under. Thats why code calls for two drains on the same pipe that can Bototh handle all the suction of the pump by them selves. or when it's not cloged each only draws 50% of what the pump can do.

2. In the winter you do not want to be drawing or mixing the water at the bottom of the pond this is the warmest water the fish have and draining it and pulling cold water down can be an issue if done wrong.

3. it's a penetration in the liner, that could fail. unless you make the trench for the pipe just like you were if you were going to have the pipe below the liner. But instead have the liner in the trench and the pipe placed in the same trench on top of the liner that will now be inside the pond and then hide the pipe with rocks etc.

4. I cover the drains with an aquablock and large rocks on top of that , as i have had fish get sucked in to the drain, or held stuck to the drain and get nasty sores

 

[GaryMoz]

The ONLY disadvantages to a bottom drain are as follows.
1. YOu realy need two so if a child is underwater and gets to close that they don't get caught in the suction and held under. Thats why code calls for two drains on the same pipe that can Bototh handle all the suction of the pump by them selves. or when it's not cloged each only draws 50% of what the pump can do.

2. In the winter you do not want to be drawing or mixing the water at the bottom of the pond this is the warmest water the fish have and draining it and pulling cold water down can be an issue if done wrong.

3. it's a penetration in the liner, that could fail. unless you make the trench for the pipe just like you were if you were going to have the pipe below the liner. But instead have the liner in the trench and the pipe placed in the same trench on top of the liner that will now be inside the pond and then hide the pipe with rocks etc.

4. I cover the drains with an aquablock and large rocks on top of that , as i have had fish get sucked in to the drain, or held stuck to the drain and get nasty sores

Thanks for your reply and your points.

As far as know they are no codes for ponds in UK, so should be ok with one bottom drain (if I ever do get grandchildren I'll put a safety grid over the pond)

I've just been looking through your showcase and the detailed thread, they are going to be very useful.

 

[GBBUDD]

Thanks for your reply and your points.

As far as know they are no codes for ponds in UK, so should be ok with one bottom drain (if I ever do get grandchildren I'll put a safety grid over the pond)

I've just been looking through your showcase and the detailed thread, they are going to be very useful.

Glad it can help . As to the main drain though code or no code I'd still do a double drain or more depending how big the pond is

 

[diy Dave]

The more I research building a wetland/bog filters the more confused I get. I'm looking to turn a pool into a pond, it will be about 3000 gallons and the area I have set aside for the bog is approx. 36 inches deep and 20-30% of the area of the pond. I'd like to have the option to take a dip in the pond if possible. Not so much an all out recreation pond, but I'd like the option if I can get away with it. This is why I was following the Aquascape style since it has so much documentation as being used for recreation/swim ponds.

I initially was going to follow this DIY article I found. http://www.bogfiltration.com/making_your_own_upflow_bog_filte.html It is essentially the aquascape method, but without aquablocks and a DIY centipede and snorkel out of Drain pipe. I was going to use 8 inch double wall drain pipe and a 14 inch drain pipe chimney. Then the layers of large medium and then small rocks. I can't seem to find much on this method that doesn't involve the aquablocks (which I can't afford).

The more I read, I then came across this method, that seems to have a lot of support (some on this sub) and the author themselves say it will work with a pond my size. It is cheaper and easier than the previous method. They even mention that the number one mistake people make in bog filters in making them too deep?

https://nelsonwatergardens.com/gravel-bog-filter-construction/ Highlights of this method: 12 inch deep, all pea-gravel, 2 inch pipe in a grid style pattern at the bottom.

Then there is the Aquascape method. That has a pre-fab 12 inch bottom drain and a 14 inch clean out chimney. They call for a layer of aquablock and a layer or large rocks, layer of medium rocks and then a layer of small gravel. These wetland filters are typically three to four feet deep.

Does anyone have any advice on which I should pursue? I can't afford the amount of aquablocks or the prefab equipment I would need to do it their way. I was thinking I could get away with the Drainpipe DIY method without the aquablocks, but now I am second guessing myself. I hate to spend the extra money on the depth and extra couple tons of rock if all I really needed was 12 inches of pea-gravel to achieve the same results.


The more I research building a wetland/bog filters the more confused I get. I'm looking to turn a pool into a pond, it will be about 3000 gallons and the area I have set aside for the bog is approx. 36 inches deep and 20-30% of the area of the pond. I'd like to have the option to take a dip in the pond if possible. Not so much an all out recreation pond, but I'd like the option if I can get away with it. This is why I was following the Aquascape style since it has so much documentation as being used for recreation/swim ponds.

I initially was going to follow this DIY article I found. http://www.bogfiltration.com/making_your_own_upflow_bog_filte.html It is essentially the aquascape method, but without aquablocks and a DIY centipede and snorkel out of Drain pipe. I was going to use 8 inch double wall drain pipe and a 14 inch drain pipe chimney. Then the layers of large medium and then small rocks. I can't seem to find much on this method that doesn't involve the aquablocks (which I can't afford).

The more I read, I then came across this method, that seems to have a lot of support (some on this sub) and the author themselves say it will work with a pond my size. It is cheaper and easier than the previous method. They even mention that the number one mistake people make in bog filters in making them too deep?

https://nelsonwatergardens.com/gravel-bog-filter-construction/ Highlights of this method: 12 inch deep, all pea-gravel, 2 inch pipe in a grid style pattern at the bottom.

Then there is the Aquascape method. That has a pre-fab 12 inch bottom drain and a 14 inch clean out chimney. They call for a layer of aquablock and a layer or large rocks, layer of medium rocks and then a layer of small gravel. These wetland filters are typically three to four feet deep.

Does anyone have any advice on which I should pursue? I can't afford the amount of aquablocks or the prefab equipment I would need to do it their way. I was thinking I could get away with the Drainpipe DIY method without the aquablocks, but now I am second guessing myself. I hate to spend the extra money on the depth and extra couple tons of rock if all I really needed was 12 inches of pea-gravel to achieve the same results.

I worked out the math for undergravel filters which will distribute water evenly throughout the whole bog, Mike White recommends 1/4 to 3/8 holes every 12 inches with 2 inch branches 12 inches apart---but they all make a common error! they suck uot the grid with same size 2 inch pipe---huge mistake as this limits waterflow in 40 to 60 percent of the bog---what a waste!! low functioning unles you use a 4 inch diameter main trunk----then and ONLY then will you get an even suck on all the branches, provided the total surface area of ALL the holes equals 5to10 times the area of the main trunk i am using 6 times also i recommend using 2-3 inch rock BETWEEN the branches, then covered with 3-4-5 inches of 3/8 round pea gravel. The 2-3 inch rock between branches acts as a high flow plenum so all the decay gets sucked up not left to make anerobic bacteria!! ps- 1/4 inch-holes are in sets of 3. 1 at bottom and each side at 60 degrees 1 foot apart

 

[poconojoe]

@diy Dave
I don't understand "suck out the grid" or when you say " 4 inch main trunk". What main trunk?
Can you explain?

A lot of us cut slits in our manifold branches instead of drilling holes. The thought is that a slit that is cut 1/3 through the pipe (perpendicular), has a less chance of getting blocked by the rocks or gravel than a small 1/4" hole.
I spaced my slits an inch and one half apart. Others have spaced them further apart.

My bog is about 5 feet wide. I have two 2" pvc pipes 10 feet long as my manifold.

Observing my bog, I can see percolation all over the surface of the gravel, even places where I know are not directly above the manifold. It percolates all over the place.
This is why I think a lot of this figuring and thought of how things "should" be, might not really make that much of a difference.

 

[poconojoe]

@diy Dave
I probably could have spaced the slits further apart and still had great results.
Mine are spaced 1-1/2" apart.
I come to this conclusion after I had to work on my daughter's septic leach field, which functions (sort of) similarity. The spacing was 6 feet! And they were only 1/4" holes! 6 feet between holes!

So, again, there seems to be a lot of leeway in the construction of our bogs. Holes, slits, facing them up, facing them down, the spacing between manifold branches....it all seems to work. So, basically, do all the research and build it as you feel will work for you, because it WILL work.

 

[Rosegardener]

The more I research building a wetland/bog filters the more confused I get. I'm looking to turn a pool into a pond, it will be about 3000 gallons and the area I have set aside for the bog is approx. 36 inches deep and 20-30% of the area of the pond. I'd like to have the option to take a dip in the pond if possible. Not so much an all out recreation pond, but I'd like the option if I can get away with it. This is why I was following the Aquascape style since it has so much documentation as being used for recreation/swim ponds.

I initially was going to follow this DIY article I found. http://www.bogfiltration.com/making_your_own_upflow_bog_filte.html It is essentially the aquascape method, but without aquablocks and a DIY centipede and snorkel out of Drain pipe. I was going to use 8 inch double wall drain pipe and a 14 inch drain pipe chimney. Then the layers of large medium and then small rocks. I can't seem to find much on this method that doesn't involve the aquablocks (which I can't afford).

The more I read, I then came across this method, that seems to have a lot of support (some on this sub) and the author themselves say it will work with a pond my size. It is cheaper and easier than the previous method. They even mention that the number one mistake people make in bog filters in making them too deep?

https://nelsonwatergardens.com/gravel-bog-filter-construction/ Highlights of this method: 12 inch deep, all pea-gravel, 2 inch pipe in a grid style pattern at the bottom.

Then there is the Aquascape method. That has a pre-fab 12 inch bottom drain and a 14 inch clean out chimney. They call for a layer of aquablock and a layer or large rocks, layer of medium rocks and then a layer of small gravel. These wetland filters are typically three to four feet deep.

Does anyone have any advice on which I should pursue? I can't afford the amount of aquablocks or the prefab equipment I would need to do it their way. I was thinking I could get away with the Drainpipe DIY method without the aquablocks, but now I am second guessing myself. I hate to spend the extra money on the depth and extra couple tons of rock if all I really needed was 12 inches of pea-gravel to achieve the same results.


The more I research building a wetland/bog filters the more confused I get. I'm looking to turn a pool into a pond, it will be about 3000 gallons and the area I have set aside for the bog is approx. 36 inches deep and 20-30% of the area of the pond. I'd like to have the option to take a dip in the pond if possible. Not so much an all out recreation pond, but I'd like the option if I can get away with it. This is why I was following the Aquascape style since it has so much documentation as being used for recreation/swim ponds.

I initially was going to follow this DIY article I found. http://www.bogfiltration.com/making_your_own_upflow_bog_filte.html It is essentially the aquascape method, but without aquablocks and a DIY centipede and snorkel out of Drain pipe. I was going to use 8 inch double wall drain pipe and a 14 inch drain pipe chimney. Then the layers of large medium and then small rocks. I can't seem to find much on this method that doesn't involve the aquablocks (which I can't afford).

The more I read, I then came across this method, that seems to have a lot of support (some on this sub) and the author themselves say it will work with a pond my size. It is cheaper and easier than the previous method. They even mention that the number one mistake people make in bog filters in making them too deep?

https://nelsonwatergardens.com/gravel-bog-filter-construction/ Highlights of this method: 12 inch deep, all pea-gravel, 2 inch pipe in a grid style pattern at the bottom.

Then there is the Aquascape method. That has a pre-fab 12 inch bottom drain and a 14 inch clean out chimney. They call for a layer of aquablock and a layer or large rocks, layer of medium rocks and then a layer of small gravel. These wetland filters are typically three to four feet deep.

Does anyone have any advice on which I should pursue? I can't afford the amount of aquablocks or the prefab equipment I would need to do it their way. I was thinking I could get away with the Drainpipe DIY method without the aquablocks, but now I am second guessing myself. I hate to spend the extra money on the depth and extra couple tons of rock if all I really needed was 12 inches of pea-gravel to achieve the same results.

 

[Rosegardener]

Hello,
I have researched hundreds of bog filters videos. I would have built one last year but I injured my back. I decided to go with the Nelson Water Garden verison with a modification. I'm going to add a mini snorkel using 4" corrugated slotted drain pipe going to a food barrel which is about 10 gal 20"x11" (big enough to drop in my submersible pump to clean out). I will dig a trench in the bottom of the bog filter to accommodate the drain pipe and a couple of inches lower for the barrel which will be the lowest point. A few river rocks will be placed over the drain pipe to lock it in place and cover it. Then I'll cover that with mesh to keep the pea gravel in place. The mesh I'm going to use is the mesh from Aquascape pondless vault. Then the rest will follow the Nelson plan with one of the horizontal pipes flowing to the drain pipe. I did contact Anita at Nelson's and they recommended using a second pump dedicated to the bog. In the Nelson video they do say if your bog is greater than 12" deep you can use rocks to fill up the bottom space then place mesh over before adding the pea gravel - 12"in - no more , no less. If you have not dug the bog yet I wouldn't go 36" deep as it is unnecessary to achieve the results you want. Save yourself some work and money. My pond is 2200 gal.
The reason I'm going with the pea gravel is that pea gravel has more surface area for good bacteria to colonize. Adding the mini snorkel allows for easy clean out that I can direct onto the surrounding garden. I was torn between the 2 different methods so I decided to combine them. Ozponds on YouTube is a great resource. This guy is in Australia and is obsessed with pond building inexpensively. Good Luck with your building.
Rose

 

[GBBUDD]

Just finished reading and watching the videos from Nelson water gardens how to build a bog. i picked up on a couple statements that were made that i do not agree with.

They did not use fabric in the bog before placing the liner. The underlayment, usually a non woven needle punched geotextile fabric is a fantastic insurance policy to help protect the liner. The fabric is available in different oz weight 3-5 is a typical landscape fabric/ weed barrier. while an 8 oz is now much harder to cut, even while using a utility knife or sheers. And 12 OZ is just an animal all in it self very tough to cut and is great as an insurance.

Cuts every inch 1/3 the way through a pvc will weaken the pipe. We have had folks say there pipes snapped and got clogged. And had to pull out the gravel to find the problem. So if you have a pump with a two inch outlet and you were to add up the cuts if you have 1/8" cut and you have 16 cuts that would come close to equaling a 2 ich opening. So if you doubled that to 32 cuts you can see there's no limit of water flow. Now they are partially blocked by gravel but when you add it up the pump will not be limited. So while you can add more cuts there is a point to where it is now a bit too weak. You want to let the water linger in the bog as long as you can let the bacteria, microbes, and insects do their job. The goal is to put water evenly across the bottom of the bog. To maximize the usable surface area of the gravel in your bog. But one thing is for sure water will fill every milk and cranny in the bog and the water will flow in one are better than another this week but may shift at any time . It will take the path of least resistance.

Also a believer in the aquablock / matrix system for a bog . This will allow for a completely even low low pressure across the entire bog . Thus any solids have the best chance to drop out of the flow up to the gravel . This will help keep the gravel clean over time.

Not a huge fan of must not exceed 12 inches of gravel . There are many and i do mean a lot of bog plants that can grow roots down to the pipes and clog them. Again we have had posts where they had this issue.

And i also disagree on must be 3/8 pea stone. 3/4 river rock is the main gravel with a layer of 3/8 mixed on top. But i have 30" total
3"to 4 " rock on the aquablocks for 6" then 24 inches of 3/4 " river rock. not papyrus or cat tails will clog my flow

 

[Lisak1]

@Rosegardener - when you say "mesh" what are you referring to?

 

[Rosegardener]

@Rosegardener - when you say "mesh" what are you referring to?

Aquascape - Aquabasin geotextile micro grid 4' x4'. (product # 87031).
( https://aquascapecanada.ca/products/aquascape-woven-microgrid-geotextile-4-x-4 )
It's intended use was for the AquaBasin. It states "allows basin to be installed with small pebbles or gravel, prevents small gravel and debris from entering the AquaBasin ). I'll be cutting mine in half to lay over the snorkel and layer of river rock to keep pebbles out of the slots in the snorkel. My bog will be 8ft. It does come on an 8 foot roll on the but you have to buy the whole roll @ $3K+. I may also use a rigid schedule 40 weeping tile pipe instead of the corrugated one because someone on here mentioned about possible collapse of pipes although they were referring to the manifold with slots being cut deep and close together. I think the corrugated pipe should be ok as they do use it at footings around foundations of houses and they don't collapse with all that soil on top.
On the Nelson video with daughter Mary and Anita, they mention if your bog is deep you can make a false bottom using crates and they mentioned that they sell "mesh".They didn't elaborate. I did email them once and they did reply about using one pump or 2. I chose the Geotextile microgrid because it's made to be used in water outdoors. You can find mesh in the dollar store but I wasn't confident that it would last.
Rose

 

[Lisak1]

Interesting - I've never seen that product before, but I would be hesitant to add anything that could potentially clog with fine debris to a bog set up.

We built our pond with a negative edge that flows into an underground water storage. We basically have a down flow bog - an area filled with gravel that the water flows through to the Aquablox below. We were advised to use a layer of geotextile on top of the blocks for the same reason - keep the small gravel from gravitating into the Aquablox. Unfortunately within a matter of weeks the fabric had started to collect microscopic debris and grow algae, effectively stopping the water flow. We used a high powered hose nozzle to rinse it down - lasted a week or two and then it started clogging again. Tried a power washer - same result. It was a constant maintenance issue. Eventually we had to dig all the gravel out and cut out as much of the stuff out as we could - total pain. We ended up replacing the pea gravel that we had used originally with a larger river stone that can't make its way through the grids on the blocks.

I only share this because I would be concerned that the same thing would happen in the reverse. When we were building our pond it never even occurred to us that the mesh could or would clog as easily and quickly and persistently as it did. Once that gravel locks in place, it's really not going to continue to gravitate downwards - especially when you're pushing water up through it.

Just an opinion.

 

[addy1]

My bog, nothing but pea gravel , is 2.5 feet deep. It works great, never cleaned out in 12 years. I built before people started talking snorkels aqua blocks etc.

 

[Lisak1]

My bog, nothing but pea gravel , is 2.5 feet deep. It works great, never cleaned out in 12 years. I built before people started talking snorkels aqua blocks etc.

It was so much easier before all the "bog rules" were established!

I think too many folks think way too hard about way too many things when it comes to bog construction. The basics are simple - water flowing up through gravel with plants growing at the surface. Whether you cut slits or drill holes, add 12 inches of pea gravel or 4 feet of graduated size gravel, use 2 inch or 3 inch PVC or a whole centipede and snorkel system just really isn't all that important as long as you have those elements in place. A - you'll probably never see your plumbing under all that gravel again so you'll have no idea what's going on down there and B. if the bog is working to keep your pond healthy, you'll see it with your own eyes.

I've found that people who believe they know THE WAY things should be done have many times only done it one way - theirs. And we know from this forum that LOTS of ways can work.