Bog filter big enough

[sompa]

I am in the planning stage of making my koi pond. I am planning on making an upward bog filter out of half a blue 55 gal plastic barrel. My pond will approximately be 25ft long and 5 feet wide and depth will very but the deepest will be 4 feet. If this isn't big enough what if I use both halves of the barrel and have two bog filters?

I am new and just trying to figure everything out early so I make a few mistakes as possible. Thank you for any advise and help you can give me.

 

[Lisak1]

Welcome to the GPF!

As a rule of thumb, you want the surface area of your bog to be approximately 30-40% of the surface area of your pond. You want lots of room for plants and gravel - the two more important components of any bog filter.

Your plastic barrel idea sounds more like a skippy filter than a bog filter.

 

[j.w]

@sompa

 

[brokensword]

what Lisa said; you'll get some filtering but you'll flounder if you intend to keep that size pond going with barrels. I use to have a 4'x4' x3' deep bog v1 for a pond a lot smaller than yours and eventually, found out it's limitations. Bog v2 is now 20' x 3' x 3' deep; I'm much happier.

 

[Mmathis]

Hello and welcome! Agree with what @Lisak1 said.

 

[Tula]

I use a 55 gallon barrel for a sand and gravel filter and supplement it with a bog.

 

[addy1]

Welcome to the forum!

Agree with all above. I have just shubunkins. My bog is 27 x 4.5 x 2.5 the pond is 27 x 10-20 x 5.5 to 1 feet deep more or less. The bog takes care of the pond perfectly.

 

[sompa]

So my bog will now be 5x5x18in. What size pipe should I use in the bog? I will be using 1 1/2 in from pump to the bog? Should I use 2 in or stay with 1 1/2 all the way through?

 

[Mmathis]

Others will be able to give you good advice. I don’t know if mine is good or not, but it worked for me. And, my memory may not be 100%, either, so……. The pipe in my manifold (the part that goes underneath the gravel) was 2”. I think I used 1 1/4” or 1 1/2” in pipe going in (from the pump), but used something like 3”- 4” pipe returning to the pond.

 

[poconojoe]

What Lisa said.
Bog's surface area should be at least 30% of the pond's surface area.
The gravel should be at least 12" deep.

I don't know if half of the 55 gallon barrel meets those requirements. You will have to measure.

Mine is just a bit over 30% and it works great.

One other thing...if I were to start over, I would not have had koi. They get huge and put out a lot of waste, plus they definitely will multiply which will cause even more overload.
Take a look at shubunkins. They are beautiful long finned fish that won't grow too big, so you can have plenty of them along with various type of goldfish without stressing your system.

 

[poconojoe]

I opted for 2" pvc for my manifolds. I thought it might allow for less buildup inside the manifolds.
My pump has an 1-1/2" outlet and I switched to 2" for under the gravel. I don't know if that was necessary (probably not), but I figured once it's covered with gravel it's pretty much permanent.