Gravity Fed filter using settlement chambers and biological filtration. No cutting of pond liner.

[Ray G]

The filter I have made has been in use for years. The water is crystal clear even in the hottest summer.
The filter has a large capacity and is gravity fed from a pipe in the pond. There is no drain cut into the pond lining at all.
The video shows the main parts of the filter set up. I will add more details if anyone is interested. I clean the filter every 2 months or so.

 

[Lisak1]

Thanks for sharing! Your fish are gorgeous!

What's the purpose of the waterlilies in the chamber? Is the netting on permanently or is that for leaf dropping?

 

[Ray G]

Thanks for sharing! Your fish are gorgeous!

What's the purpose of the waterlilies in the chamber? Is the netting on permanently or is that for leaf dropping?

The waterlilies help use up the nitrogen from the fish waste. I find that things like that and watercress (in season) really improve the water quality in the pond. The netting is mainly to stop frogs from breeding in the filter. Without the netting I would have many frogs in each chamber all the time. The netting (on top of an open steel mesh) stops the frogs. Stopping the leaves is a bonus and means I don't have to clean the filter out much at all.

 

[nomadh]

I had to sign up to comment. Sorry I'm sort of skipping the introductions and jumping in. Hope nobody minds. I was going to post this an a new thread but instead I wanted to pick the brain of the OP. Hope you are still around and listening.
I did a design similar to yours but for my 500 gal above ground pond. It has worked great for years and with as close to 0 maintenance as I could imagine.
I like to follow the design concepts of :
1. No holes in the liner.
2. Gravity feed to your prefilter so your pump doesn't grind up the fish waste making it harder to filter and feeding the algae.
3. Gravity feed to your settling chamber so you can filter before the pump. (can be the same a pre)
4. Biofilter after your pump so the biofilter never needs cleaning.
5. Always biofilter in a dark oxygen rich environment like an enclosed trickle tower spraybar setup into your bio media.
6. Waterfall back into the pond for oxygen
The only way I know to do this is with a siphon tube.
It works great on my 500 gal above ground pond but it hasn't translated that well to my Mother-in-laws 1500 gal in ground pond.
In my pond the siphon is a U shaped tube where with the pond filled and prefilter 1/3 full I dunk the entire U tube in my pond to fill it underwater. Put caps on the ends Pull it out and put 1 end in the pond and another in the pre where the end is underwater. I pull the caps and the prefilter fills in seconds to equalize levels and I know I got a good siphon that can last all year sometimes.
Doing this on a big pond and at ground level does not work well. Its such a pain I've been contemplating cutting a hole in the liner. Maybe just a foot below water level in case of a leak it wont be catastrophic. From there I can run the pipe inside the pond to the bottom area and plumb to 1 foot down into the side of my prefilter.
Just as I was thinking this was a good compromise my mother in law left the water running and overflowed the pond. A couple koi died but we saved most of them. But what really worried me is my buried trashcan prefilter was lifted out of the ground when she overflowed her pond. If I had connected my pond to my pre like I was planning I certainly would have ripped the liner as the filter rising would have lifted my pipes up also.
So to the OP, @Ray G, how do you get your siphon tube full of water while keeping it in place? I was considering a couple of ball valves just below the water lines. Is that what you did? You cant just open the inspection plate and pour water in. Whats your process?
Thanks for the help.

 

[Ray G]

I had to sign up to comment. Sorry I'm sort of skipping the introductions and jumping in. Hope nobody minds. I was going to post this an a new thread but instead I wanted to pick the brain of the OP. Hope you are still around and listening.
I did a design similar to yours but for my 500 gal above ground pond. It has worked great for years and with as close to 0 maintenance as I could imagine.
I like to follow the design concepts of :
1. No holes in the liner.
2. Gravity feed to your prefilter so your pump doesn't grind up the fish waste making it harder to filter and feeding the algae.
3. Gravity feed to your settling chamber so you can filter before the pump. (can be the same a pre)
4. Biofilter after your pump so the biofilter never needs cleaning.
5. Always biofilter in a dark oxygen rich environment like an enclosed trickle tower spraybar setup into your bio media.
6. Waterfall back into the pond for oxygen
The only way I know to do this is with a siphon tube.
It works great on my 500 gal above ground pond but it hasn't translated that well to my Mother-in-laws 1500 gal in ground pond.
In my pond the siphon is a U shaped tube where with the pond filled and prefilter 1/3 full I dunk the entire U tube in my pond to fill it underwater. Put caps on the ends Pull it out and put 1 end in the pond and another in the pre where the end is underwater. I pull the caps and the prefilter fills in seconds to equalize levels and I know I got a good siphon that can last all year sometimes.
Doing this on a big pond and at ground level does not work well. Its such a pain I've been contemplating cutting a hole in the liner. Maybe just a foot below water level in case of a leak it wont be catastrophic. From there I can run the pipe inside the pond to the bottom area and plumb to 1 foot down into the side of my prefilter.
Just as I was thinking this was a good compromise my mother in law left the water running and overflowed the pond. A couple koi died but we saved most of them. But what really worried me is my buried trashcan prefilter was lifted out of the ground when she overflowed her pond. If I had connected my pond to my pre like I was planning I certainly would have ripped the liner as the filter rising would have lifted my pipes up also.
So to the OP, @Ray G, how do you get your siphon tube full of water while keeping it in place? I was considering a couple of ball valves just below the water lines. Is that what you did? You cant just open the inspection plate and pour water in. Whats your process?
Thanks for the help.

What a lot of great concepts you have listed. And I agree with them and that is why I built mine the way I did. Mine is a big pond and a big pump so needed a large diameter pipe as the siphon or I would lose too much suction pressure with the pump in full swing. So my siphon pipe is 6inch sewer pipe basically. So at the top I have an inspection cap (at the highest point in the pipe). I cover both ends of the pipe and fill up the pipe through the cap. until it is overflowing. then I screw the cap on tight (it is air tight). I have then a perfect siphon. I have a lot of holes in the intake pipe so that the gravity feed is not restricted when the pump starts. I have about 1000 1/4" holes in the pipe. This means that there is no strong acceleration of water into the intake pipe and therefore it does not clog with leaves (or anything). Please ask more questions. I found the biggest challenge was getting the flowrate enough to feed the pump without sucking the waterlevel too low. My filter requires no real maintenance and the water is always crystal clear. nothing clogs.

 

[nomadh]

What a lot of great concepts you have listed. And I agree with them and that is why I built mine the way I did. Mine is a big pond and a big pump so needed a large diameter pipe as the siphon or I would lose too much suction pressure with the pump in full swing. So my siphon pipe is 6inch sewer pipe basically. So at the top I have an inspection cap (at the highest point in the pipe). I cover both ends of the pipe and fill up the pipe through the cap. until it is overflowing. then I screw the cap on tight (it is air tight). I have then a perfect siphon. I have a lot of holes in the intake pipe so that the gravity feed is not restricted when the pump starts. I have about 1000 1/4" holes in the pipe. This means that there is no strong acceleration of water into the intake pipe and therefore it does not clog with leaves (or anything). Please ask more questions. I found the biggest challenge was getting the flowrate enough to feed the pump without sucking the waterlevel too low. My filter requires no real maintenance and the water is always crystal clear. nothing clogs.

So how do you cap the siphon tube when it has 1000 holes? This is the missing part I'm not seeing. I was considering a ball valve at each end under the pond and filter water level. Just wondering if there is a better or cheaper answer. I'm worried the ball vales will become inoperable after some time being in the water. I dunk and cap the U shaped siphon part on my small pond but thats whats unwieldy on this big one.
I've been using 3" (iirc) pipe and yes my pump will certainly suck down my filter side. I may go with two 3" pipes side by side as a 6" I think would look pretty big coming over the pond edge but maybe I should just landscape better in that area. Also for my 1500 gal pond I'm only using 1 30 gal trash can. I have another sunk in the ground but was bypassing it because of this siphon problem. I was hoping to run both in parallel to slow down he flow and help the solids settle but I'm not sure it will be enough to help.

 

[Ray G]

So how do you cap the siphon tube when it has 1000 holes? This is the missing part I'm not seeing. I was considering a ball valve at each end under the pond and filter water level. Just wondering if there is a better or cheaper answer. I'm worried the ball vales will become inoperable after some time being in the water. I dunk and cap the U shaped siphon part on my small pond but thats whats unwieldy on this big one.
I've been using 3" (iirc) pipe and yes my pump will certainly suck down my filter side. I may go with two 3" pipes side by side as a 6" I think would look pretty big coming over the pond edge but maybe I should just landscape better in that area. Also for my 1500 gal pond I'm only using 1 30 gal trash can. I have another sunk in the ground but was bypassing it because of this siphon problem. I was hoping to run both in parallel to slow down he flow and help the solids settle but I'm not sure it will be enough to help.

the part with the 1000 holes I add once the tube is full and I remove the caps. I simply insert it into the open end in the pond. It is under the water. easy to do and doesn't need to be a watertight fit of course as it is under water. You can see from my video about the filter that I use concrete boxes for the filter chambers with underwater piping from one chamber to the other. I get really slow flows through each chamber as the cross-sectional area of the chambers is huge compared to the pipe in the pond. The 6" pipe I cover with landscaping materials so you cannot see it from above normally. I also put some spare pond liner over it to cover it from sight sometimes. There are many advantages of the 6" compared to the 3" pipe and you have identified many yourself. One big siphon is way less trouble than 2 smaller ones. I have never used any valve at either end. As there are no holes in the liner I cannot see how either end of the siphon would ever be out of water with my setup. As long as they are both in water then the pipe will stay full and feed water to the pump. I cant stress enough the need to ensure that the siphon can carry the full pump capacity to the pump.

 

[Ray G]

The waterlilies help use up the nitrogen from the fish waste. I find that things like that and watercress (in season) really improve the water quality in the pond. The netting is mainly to stop frogs from breeding in the filter. Without the netting I would have many frogs in each chamber all the time. The netting (on top of an open steel mesh) stops the frogs. Stopping the leaves is a bonus and means I don't have to clean the filter out much at all.

Some photos or video of what you are doing with the filter would be great. At this forum we love photos and videos of what is going on!! Good luck and ask questions. The size of your pump is the critical factor when determining the diameter of the siphon tube.

 

[TimL94]

This is the exact same thing that I am about to try and achieve as well, I don't know if I am bad at googling but I have hardly found anyone else talk about trying this sort of thing other than people saying "why not just put in a bottom drain".... As you say, my main concern also is pump emptying the filter faster than the U Bend keeps it topped up. Although I dont intend on having plants involved just linking a couple barrels up with a pump in the last one. I'll try do a diagram or something.

 

[Ray G]

I did the calculations to determine the diameter of the pipe. with the pipe I have there is so little friction loss that I lose almost no water height in the filter compared to the pond when my pump is going flat out. I have a couple of videos on my YouTube site showing the set up I have. The holes in the inlet pipe turned out to be as critical as the diameter of the pipe. I initially started with 250 1/4" holes but that was not enough to keep the water flowing at the right height. Check the 2 videos on my YouTube site and then ask questions and I will keep an eye on this thread. My set up requires no real maintenance for months and months.

 

[TimL94]

Yea I watched your videos, looks awesome! nice fish. Your pond is a lot bigger than mine (I think mine is just over 5,000L), and the filter tanks I have are 3x 220L water drums. I was thinking I'd only go for a 110mm U Bend (I don't think much bigger is readily available in the UK...?) and for the pump I was thinking either Aquaeco 12,000L/H or Fish Mate 9,000L/H, feeding to a low waterfall.

I was going to have a settling drum (I guess I could stick some plants in there), then an air rated drum with media and then 3rd tank with lava rocks and pump. I'll have a think about what sort of questions I have while I'm at work today. Any advice is greatly appreciated!

 

[Ray G]

I think that 12,000 L/H is too much for a 5000L pond. Also the flow rate will be too fast in the tanks for settlement. The 110mm pipe should be fine but I would go for about 5000L/H flow as a max. Your filter chambers will be smaller than mine so your flowrate should not be too fast to get settlement and good filtration. 3 chambers (tanks) sound fine to me. Getting it all to work so that settlement happens is the main thing I reckon.

 

[TimL94]

Ahh ok, also probably worth mentioning it isn't a Koi pond it's gold fish + couple other species of UK Native fish. So I don't think the waste will be too bad, but yea.
I was thinking the design of settling chamber will contain an inner chamber and then surface drawing, similar to the one in this video I guess

I don't really know what a decent water flow on a waterfall looks like when comparing L/H, maybe I could have a skimmer feeding to the waterfall too?

 

[Ray G]

Ahh ok, also probably worth mentioning it isn't a Koi pond it's gold fish + couple other species of UK Native fish. So I don't think the waste will be too bad, but yea.
I was thinking the design of settling chamber will contain an inner chamber and then surface drawing, similar to the one in this video I guess

I don't really know what a decent water flow on a waterfall looks like when comparing L/H, maybe I could have a skimmer feeding to the waterfall too?

It depends on the width of the waterfall as to what the flowrate looks like. If you go too high with the flowrate through the filter you will not get the settlement you need. So yes if you want heaps of water on the waterfall (always nice) then an additional feed from a skimmer would work.

 

[TimL94]

Hopefully off to buy some pipes and whatnot later, I'll keep you updated, for better or for worse haha!