Horizontal bog filter (length instead of height)

[Dann1s]

Fellow pond lovers!

Last year I got hit by the Koi flu! A few months ago I started digging in my garden as preparation for a koi pool. The 'hole' that i'm going to use is finished and has the following dimensions in metres: 2.40 wide, 1.80 deep and 4.40 in length.

The next step is to make a lay-out of the pool. Since I decided to use a bog filter as filtration, a significant part of the surface needs to be for filtration. The problem is that, because of factors, I can only use the lengths of the area. I came up with a concept of which I couldn't find anything on the forum. I hope some fellow pond lovers could answer my question or give some feedback on the layout.

I'm becoming a real koi, pond and bog hobbyist, but I'm still a beginner in all topics. I would love to receive some feedback from others.

Concept Layout
If you look at the basic (active) bog filters, you can find a certain basic. The dirty pool water starts at the bottom of the bog filter. After that, it is pumped up through some layers of rock. At the surface the water will be redirected to the pool as filtered water. In other words, the water is pumped from low to high.

In my layout, the water will be pumped through a horizontal line of chambers. Those chambers are filled with different sizes of rock and each chamber is connected through pipes or fences. The opening in the fences or the pipes are variably at the top and bottom of each chamber. There are 8 chambers in total and they are 30 centimetres (12 inches) high.

My doubts
I do not know however if this system can operate effective enough to filter the entire pool. The filter will be around 3.2 square metres and 1 cubic metre for the remaining pool size of 8.8 square metres and 14 cubic metre. It will cover around one third of the total pool surface. I hope another Koi or Bog filter fanatic can give their view on this concept.

My question
I mostly wonder how fast the water of the pool has to be pumped through the bog filter. I am able to buy a pump that can pump through 30 cubic metres through the big filter per hour. The forum seems to suggest that this is a good idea. However, that is with bog filters that pump upwards.

Question 1: How many times per hour should the pool water be filtered according to you, based on this concept?

Question 2: If I would pump through the entire pool water volume through this bog filter twice per hour, will the bacteria and plants have enough time to effectively do their jobs within the filter?

I drawed some pictures of the suggested layout. Don't mind the drawing skills, I never was an artist at high school

 

[AlyssaFish]

I did something like this once. Basically had planters that the water would travel across sideways, to an outlet on the other side. My greatest struggle was avoiding overflowing. I ended up having to dig "rivers" into the pea gravel where some of the water could flow across the top of the gravel surface without having to go through the gravel, because it would simply travel too slowly through the gravel and end spilling over the edge of the planters. This meant that the water didn't cross through the gravel as much as I wanted it to, but I didn't see any way around it.

You might be able to resolve that by having greater bog dimensions, high walls, a very slow pump, or larger gravel with more space for the water to travel through.

If you get it to work, though, I see no reason it shouldn't be as effective as the vertical bog filter!

 

[j.w]

@Dann1s
Not sure that pond will be big enough for koi. Koi need 500 to 1000gals per fish. Might want to go w/Shubunkins.

 

[poconojoe]

Why don't you just create one long bog? Why all the separations? Why make it more complicated than it has to be? Or maybe I'm just not understanding something.

One long chamber with a long PVC manifold covered with 12" of gravel.

It can still make the 90 degree turn if you like. Just make sure the sides are higher than the spillway returning to the pond. The spillway will be the low point. The bottom of the spillway will be at the level of the top of the gravel. Make the sides 5"-6" higher than the gravel for safe measure.

 

[poconojoe]

I'm not so great with meters compared to feet.
If I figured it correctly, I'll have to agree with j.w., that size pond doesn't seem big enough for koi.

No disrespect. I just wish someone would have enlightened me when I first started out...

I think out of all the pond misconceptions, water volume is the biggest one when it relates to keeping koi. Everyone wants a "koi pond". It's not the fault of the novice, it's just one of those very common misconceptions.

Take a look at shubunkins. They're beautiful fish. Plus there are a lot of nice goldfish too.

 

[addy1]

Welcome to our forum!

That is around 3905 gallons, big enough for 3-4 koi with babies removed constantly. Keep in mind they get huge, demand high filtration, lots of water movement. Shubunkins, gold fish are so much easier to care for and just as pretty

 

[Phaewryn]

At 3698.41 gallons (which is what Google tells me 14 cubic meters equates to) you can have three koi, and maybe a few goldfish.
https://everythingkoi.com/blog/deciding-how-many-koi-fish-to-put-into-your-pond/
If you go with just goldfish, at 20 gallons per inch of fish, you can have many more fish (depending on the size). If you have your heart set on more than a couple koi, keep digging.

Ideally, the total water volume should be turned over each hour. If you're pushing water uphill, your pump will need to be strong enough to do the full hourly turnover of the total water volume plus the extra flow to push the head. So for a 4000 gallon pond, you'd typically want a 5000-6000GPH pump, but that depends on how high the water has to run uphill (head). It looks like your plan is to run flat compartments and push the water through them, so you will not need to add any pump volume for the head, since you don't have any. A 4000GPH pump should work for your current design, but IMO, there is no such thing as overkill when it comes to pumps. I believe the bigger the better. I have a 1200GPH pump in my 65-70 gallon pond (but I do have about 4 or so feet of head and a fountain it's pushing).

Most people have a raised bog filter to incorporate a waterfall to assist in aeration. You're going to also need to run a big fountain or aerators if you have no falling water. I'm not a koi expert. I think you could probably make your plan work, if you include a fountain/aeration and either make everything proportionally bigger or stick to 3 fish (or have a plan to exchange your bigger fish for smaller ones as needed). I don't think you want pipes in the bog sections. You want to push the water into the end of the system, then let it push it's way through the gravel from there. If you have pipes in the gravel, it's bypassing the filtering effect of the gravel.

 

[j.w]

Yep you are right @addy1 I found a meter calculator and put in the #'s and came up w/4,181 gals. So the poster could have around 4 or so koi depending on male or female.
https://www.hydra-aqua.com/hydra-pond-volume-calculator-litres-gallons.html

 

[Jhn]

@Phaewryn Using slotted pipes for the bog won’t bypass the filtering effects of the gravel, as the only filtering effect the gravel provides is surface area for bacteria to colonize it is the plants in the bog that are doing the bulk of the nutrient removal. In fact if you don’t use pipes to force the water up from the bottom the gravel will eventually clog causing the water to channel across the top of all the gravel/stone in that design and pretty much limiting the contact of nutrient rich pond water to a small area of the bog. Rendering the bog much less effective.

@ the OP, Not sure what the idea is going from big rocks to medium to gravel horizontally. The idea behind this in vertical bogs with Large/Medium/small aqua blocks and a centipede/snorkel is to let Silt settle out as the speed of the water is slowed as it enters the centipede then it slowly builds acceleration as it goes up through the smaller and smaller rocks, also need the large rocks to keep the gravel out of the aqua blocks. Then you can pump out the silt through the snorkel.

 

[Phaewryn]

@Phaewryn Using slotted pipes for the bog won’t bypass the filtering effects of the gravel, as the only filtering effect the gravel provides is surface area for bacteria to colonize it is the plants in the bog that are doing the bulk of the nutrient removal. In fact if you don’t use pipes to force the water up from the bottom the gravel will eventually clog causing the water to channel across the top of all the gravel/stone in that design and pretty much limiting the contact of nutrient rich pond water to a small area of the bog.

Huh, interesting. So basically it's not moving the water clockwise like drawn, it's just a regualr bog filter that covers two sides ans isn't raised? Will that work?

 

[Jhn]

Huh, interesting. So basically it's not moving the water clockwise like drawn, it's just a regualr bog filter that covers two sides ans isn't raised? Will that work?

No the bog is raised, the water will still flow clockwise, but it will be forced up from the bottom the length of the bog then out into the pond. The water won’t just flow in the pipe to the end of the bog and just go up dumping into the pond. It will go up through the gravel the entire length this way.