The Accidental Pond - filter problem

[Dirty]

Nice pond! Thanks for the pictures!

What about all that space in the foreground of the last picture? The end where the pond is wider. There looks to be plenty of space for a bog.

Some here have gone deeper where they didn't have the space. I can't vouch for that, so hopefully they will see this and chime in.

Thank you.

Yes you are right, there is space at the other end but it would be a job to run electricity there. I have power in the shed already so it's a simple task to put an extra pump in close by. The garden is on a higher level to the house and there is a concrete wall and concrete steps. Any power supply to the rear of the garden would have to run between the pond and the fence then under the waterfall. Not impossible true but not really what I want to either do or use that space for. I was going to grass it over and have it for sitting and enjoying the pond.

You have given me an idea though. I have a supply for the waterfall and vortex already. I could maybe put another small/shallow bog at the top of the water fall to the right and gravity feed it back in..........

 

[Dirty]

Mine is deep and large, deep works.

As far as large debris, pull your water about a foot off the bottom. That is what I do. I have a leaf basket before my pump (external) but never need to empty it all summer. My bog gets mainly dirty but debris free water.

Great thanks.

I have 2 bottom drains already installed. I'll have to have a leaf basket.

I have a question about the pipework with slits cut in. I understand this would distribute the pond water evenly over the bog, but doesn't that also mean that the water that exits nearest the outflow will get the least treatment? Do some bog filters have water simply dumped in one end and flowing out the other (also potentially with a system of internal barriers to ensure all areas get roughly equal flow)? Pro's, cons?

 

[Shell-Fish]

Great thanks.

I have 2 bottom drains already installed. I'll have to have a leaf basket.

I have a question about the pipework with slits cut in. I understand this would distribute the pond water evenly over the bog, but doesn't that also mean that the water that exits nearest the outflow will get the least treatment? Do some bog filters have water simply dumped in one end and flowing out the other (also potentially with a system of internal barriers to ensure all areas get roughly equal flow)? Pro's, cons?

You could always cut thinner slits closest to the water entry and make the other slits middle to other side larger, that way water is some ways distributes evenly...if that makes sense.

 

[poconojoe]

As far as electricity all the way back there, you don't need any. The bog doesn't need electricity. Your pump sends the pond water to the bog and the water flows back to the pond via gravity. The bog is higher than the pond. How much higher is up to you. It can be just a little higher, built partially above ground or a lot higher built completely above ground.

To me, that spot back there is perfect.

Due to the force of your pump, the water in the slit pipes will spread evenly. The water will hit a dead end at the end of the pipe and will get forced through the slits.

 

[addy1]

Mine is 26ish feet long, the slits near the pumps are further apart then the slits at the far end of the bog. It is working great.
You don't need power, like @poconojoe says, to run your bog, just a pump , a T off your existing pump or a new pump and just run the lines to the bog.

 

[Tula]

This is our first year with a bog. Ours is small, probably not 30 % of pond's surface and our pond water is crystal clear. I should mention it's not our only filtration as we have a ( hideous looking ) sand & gravel filter. If I thought I could get away with it, down the road we might lose the sand & gravel filter.....but we have 4 large koi.

Your pond is very pretty

 

[Dirty]

Mine is 26ish feet long, the slits near the pumps are further apart then the slits at the far end of the bog. It is working great.
You don't need power, like @poconojoe says, to run your bog, just a pump , a T off your existing pump or a new pump and just run the lines to the bog.

Yup, although rather than run new pipe, which would be a long run and take a lot of Pressure away as my filter pump is quite small and only 6000lph, I'll just run a spur off the waterfall supply which is already up that end and build a bog at the same height and run it back into the waterfall, that should work.

Re the pipe slits distance, yes, excellent idea to even out the flow. But what I'm trying to get my head around is why even out the delivery of water to the bog at all? Why not dump it all in one end and force it to take as long a route as possible through the bog touching as much of the gravel as it can?

 

[brokensword]

Yup, although rather than run new pipe, which would be a long run and take a lot of Pressure away as my filter pump is quite small and only 6000lph, I'll just run a spur off the waterfall supply which is already up that end and build a bog at the same height and run it back into the waterfall, that should work.

Re the pipe slits distance, yes, excellent idea to even out the flow. But what I'm trying to get my head around is why even out the delivery of water to the bog at all? Why not dump it all in one end and force it to take as long a route as possible through the bog touching as much of the gravel as it can?

The idea is to push the water to the BOTTOM of your bog, have it distribute throughout the whole area and rise up through the gravel where the bacteria will colonize (and convert ammonia to nitrite, and nitrite to nitrate) and the plant roots will eat up the nitrates. Putting water in one end (on top, if I'm reading your response correctly) will soon find failure as the algae and debris will clog up the system and then only flow over the gravel instead of through it. If you were to have the water go through the length using baffles, etc, it would clog soonest at the first baffle and then you'd need to clean it out. This way, consider the whole length as one large(st) baffle and if large enough, won't need cleaning anytime soon.

Deep works fine, too; ;mine is 3' deep with 8" of large 4"- 6" boulders as the base around the tube (I used a 4" drain pipe, then cut slits), followed by 12" of 2" river rock, then a final 12" layer of pea gravel. You need to use all rounded stone as anything with an edge will eventually clog/cut/fuse.

Hope this clarifies.

 

[Dirty]

The idea is to push the water to the BOTTOM of your bog, have it distribute throughout the whole area and rise up through the gravel where the bacteria will colonize (and convert ammonia to nitrite, and nitrite to nitrate) and the plant roots will eat up the nitrates. Putting water in one end (on top, if I'm reading your response correctly) will soon find failure as the algae and debris will clog up the system and then only flow over the gravel instead of through it. If you were to have the water go through the length using baffles, etc, it would clog soonest at the first baffle and then you'd need to clean it out. This way, consider the whole length as one large(st) baffle and if large enough, won't need cleaning anytime soon.

Deep works fine, too; ;mine is 3' deep with 8" of large 4"- 6" boulders as the base around the tube (I used a 4" drain pipe, then cut slits), followed by 12" of 2" river rock, then a final 12" layer of pea gravel. You need to use all rounded stone as anything with an edge will eventually clog/cut/fuse.

Hope this clarifies.

Yes it does 100% thank you.

 

[poconojoe]

My 3600 gph submersible pump has an 1-1/2" outlet size. I ran 1-1/2" flexible PVC from the pump on the opposite end of the pond up to the bog. There I increased the size to 2". I used a "Y" fitting to split it into two manifolds. I cut the slits in the manifold pipes 1/3 through the diameter of the 2" PVC and spaced them every 1-1/2".

I opted for a clean-out stack on the end of each pipe. I figured better have them just in case. When I first ran the bog, the flow slowed down a bit and I flushed it out with the clean-out stacks. That happened a couple times within the first couple of weeks, but since my water has turned crystal clear, the flow has been steady.

Some people face the slits down, some face them up. It seems to be a personal preference.

 

[Dirty]

I'm guessing you have to push the water through the bog with a pump? Not advisable to use a gravity feed?

 

[brokensword]

I'm guessing you have to push the water through the bog with a pump? Not advisable to use a gravity feed?

I've done it both ways and think it works better with the pump. That is, I pumped the water into a barrel for pre-filtration with the output exiting into a pipe that connected to the bottom of my bog. The higher your water supply (to the bog), the more force gravity can exert to get a flow going at the bottom, but you'll still get a natural resistance. With mine, I didn't have a 'water-tight' fitting between outflow pipe to the manifold at the bottom of the bog and since I sent my pipe down the snorkel portion, the water wanted to backflow UP this snorkel and bypass some of the gravel filtering process. If I'd made it a solid connection, it would probably have worked better but since you should be able to T off your pond pump (or, get a larger pump so the T is more effective, but also use a valve so you can manage exactly what the bog/waterfall gets), this is better imo.

The school of thought re bog flow is that the slower it goes through, the better the performance of both plants and gravel, within reason. That is, too fast and you'll not be using the gravel system most efficiently. The larger you can make your bog, the better everything works out. In my case, I started with a small bog and it worked for a few years before it got clogged. Now, I have a much larger one and can send more water into it without worrying about flow speed, simply because there's so much area/volume.

One thought; if you don't have much room on the sides of your pond, you can build something that cantilevers OVER the pond a bit and will more or less make this 'new waterfall outlet' easier; the water can just overpour and slip down the sides, giving you a large waterfall 'wall' which is great for more aeration as well as effect. With mine, I'm overhanging about 6" and the water exits down a stacked rock wall, giving a 'weeping effect'. But, this would give you more 'area' for plants/gravel/etc.

 

[brokensword]

one other thought; I advise you make a 'snorkel' portion that is LARGE enough to send a pump down into. When/If you ever have to backflush, it isn't just the manifolds you're cleaning but also any clogging that occurs at the bottom of your pea gravel layer. When you backflush, you suck out the bog using a pump down the snorkel. Once empty, you create a large push of water using your pond pump, directed at the surface of your bog. This helps break any gravel clogging. You then pump it back out using the snorkel pump and rinse and repeat until the water coming out of your bog looks clear. I tried this using normal city water pressure and a hose but was informed that this flow/pressure is insufficient to do the job. You need a decent amount of water flow and pressure from the TOP to dislodge any clogging down below, hence using the pond pump and an auxillary pump down the snorkel.

BUT! The idea is to make the bog as large as you can so you never have to do this! That's the plan, at least! Per Meyer Jordan's advice, I also think a bog prefilter is a good idea, which is why I first send all my pond water into a barrel filter, which then exits into the bog (you might think this negates the whole idea that bogs are maintenance free but I can clean my filter in less than 5 minutes, and put filter material in that is of any micron size, which then dictates how often I clean it - I have about 60 sq ft of actual filter area, so it still does the prefilter job efficiently). So you see, I still DO use gravity feed to my bog but now the run of manifolds is dual as well as longer. Large is better, both for bog (actually, it's an upflow wetlands filter, but we all call it a bog) and pond.

 

[Dirty]

I've done it both ways and think it works better with the pump.

Great, thank you

In fact thank you to everyone. This is an excellent forum.

I think I now have a plan of action that involves 2 bog filters

one other thought; I advise you make a 'snorkel' portion that is LARGE enough to send a pump down into.

Snorkel portion?

 

[brokensword]

Great, thank you

In fact thank you to everyone. This is an excellent forum.

I think I now have a plan of action that involves 2 bog filters



Snorkel portion?

Yeah, it's an optional (to me, mandatory) portion of the system. The water from the pond gets sent via pipe to your manifold pipes (I used 4") which then 'ends' at the snorkel portion. A snorkel is a vertical tube that reaches the top of your bog. It is usually capped unless you're using it. This snorkel, in my case, is large enough to put a pump into (I use a sump pump) which can facilitate the back flushing if you ever need to do it. This can be something like a 12" plastic drain pipe cut to the right length. You'd attach your manifold(s) to this so each exits into the snorkel. An important aspect here is to make your bog pitch down TOWARD the snorkel, as well as the bog walls slanting to a V shape. This all helps make sure any debris heads toward the snorkel portion. The bottom of your V will have your manifold pipes. The snorkel is at the far end of your bog inflow pipe(s). I used 4" to get more flow and more even distribution. Plus, the 4" drain pipe is silly cheap and easy to work with, plus I can get fittings to mate up to the 1-1/2" inflow pipes.