Bog dwelling time

[Sodadispencer]

Hi everyone,
Wrapping up my first pond build and am questioning my bog filter flow rate. The bog is connected to the pond by a 30 foot stream that I want between 6-7000gph through. The bog is 500 gallons (10’ by 7’ by 1’) and 40% of the ponds surface area. I have a tee fitting and ball valve right at the surface of the bog before it runs down into the manifold. My goal was to redirect some of the water before it hits the bog in order to gain a longer dwelling time in the bog. Unfortunately it doesn’t seem to be working as well as I would’ve liked and the bog is still getting around 5000gph. This means the bog is circulating close to every 5 minutes. Will this be too fast for the biological filtration? I plan on under stocking my pond (8-10 koi). Thanks for the help.

 

[GaryMoz]

It seems to be a fast flow rate, how big is the pond?

Take a a looks at Ozponds he has some good videos and talks about dwell times in bogs, If I recall he suggest 10 -15 mins

Also a lot of your bog will be pebbles and gravel so the actual about of water may 1/2 of that. I use a similar flow rate but my bog is 4 times bigger (actually it's 4 times deeper).

 

[j.w]

@Sodadispencer

 

[Sodadispencer]

It seems to be a fast flow rate, how big is the pond?

Take a a looks at Ozponds he has some good videos and talks about dwell times in bogs, If I recall he suggest 10 -15 mins

Also a lot of your bog will be pebbles and gravel so the actual about of water may 1/2 of that. I use a similar flow rate but my bog is 4 times bigger (actually it's 4 times deeper).

The pond is a little over 4000 gallons. Ozponds recommends between 5-12 minutes, and I'm not sure if he takes into account the volume of gravel or not. I'm simply using 3/8" pea gravel and some baseball-sized rock at the bottom. I assume you're incorporating void space at the bottom of your bog and a snorkel system? I can't change the footprint of my bog but I could go down at least another foot, effectively doubling my dwell time. I'd like to just stick with gravel though, as I doubt I could dig any deeper than another foot with some big trees near. I doubt I would experience a lot of anaerobic zones in the bog with such a high flow rate.

 

[Sodadispencer]

View attachment 166169 @Sodadispencer

Fellow Washingtonian! I'm in Issaquah myself. It'd be great to get some plant recommendations for our zone

 

[GaryMoz]

The pond is a little over 4000 gallons. Ozponds recommends between 5-12 minutes, and I'm not sure if he takes into account the volume of gravel or not. I'm simply using 3/8" pea gravel and some baseball-sized rock at the bottom. I assume you're incorporating void space at the bottom of your bog and a snorkel system? I can't change the footprint of my bog but I could go down at least another foot, effectively doubling my dwell time. I'd like to just stick with gravel though, as I doubt I could dig any deeper than another foot with some big trees near. I doubt I would experience a lot of anaerobic zones in the bog with such a high flow rate.

If your pond is 4000gal then your flow should be nearer 4000gph which will increase the dwell time.

I think in some of his videos ozponds does say it's not that crucial.

I always find it odd that in many articles it talks about the amount of surface area Vs volume for bogs. But doing my research I found out two main methods of bog filters, deep with a water reservoir and shallow, but appears they both work equally well, although the deeper ones are easier to clean, but more expensive

 

[Sodadispencer]

I think I’ll end up sinking my bog a foot and just adding more rock and gravel. I have a variable pump controller so I could alter the flow but I want to achieve the desired effect of a larger/louder stream. It’s almost 5 feet wide and 30 feet long so I need around 6000gph.

 

[Lisak1]

In my experience, it’s hard to find much actual scientific data about dwell time in a bog. And with the huge variations on the way folks are building their bogs, I think it would be almost impossible to have an exact formula.

I think a bigger issue with our bog is settling time - the water moves too fast to allow fine debris to settle if that makes sense.

 

[j.w]

Fellow Washingtonian! I'm in Issaquah myself. It'd be great to get some plant recommendations for our zone

I'm way up north and way west of you. We might be in the same zone but not sure how cold you get there. Lots of good plants you can grow. I have Parrots Feather, Mare's Tail, Sedges from garden stores, Water Hawthorn, Anacharis, Dwarf Cattails, Floating Hearts, and have had others like Hornwort but for some reason it keeps disappearing, Black Mondo Grass stuck in between my edge rocks w/their roots in the water, Creeping Jenny planted in the edge soil that creeps into the pond, Ferns that just show up on their own, Sweet Flag that I took out as it grew so big it busted out of the pot (looks nice but if you don't keep it small, watch out!), Water Lilies grow great but I took all those out too as I got tired of having to take them out and divide them. I had Azolla but it just went away one day, sometimes I throw in some Duckweed for the fish to eat. I have that growing in a separate small pond. Lots of other plants you can grow that others can tell you about too.

Parrots Feather:
This batch is planted in a big pot so it will not wander too much. I like the red stemmed variety the best as it is shorter and tighter forming and has small feathers.

Here is the longer, green stemmed more crawly type, I like it too and some are planted in a pot and others are just stuck in between the rocks:

Mare's Tail to the left of photo I found in a ditch up north near Blaine is planted in a pot:

Sedges I just found at the garden store and plant them in between rocks also:

Water Hawthorn gets tiny white blooms in late Summer or early Fall or Spring when temps are cooler. It's in pots. It will send out seeds that sprout while floating that you can grab out and plant in soil and start more plants:

Anacharis is the plants you can find in pet stores for goldfish and if you have a lot the fish may not eat it all and it will grow and multiply enough so they can't wipe it out. I found a wild type growing in a natural pond and collected some as the fish store type seems more finicky:

Dwarf Cattails are planted in between rocks. Here is a photo from when I had them in a bathtub pond before I moved them to my big pond:

Floating Hearts, you can plant in a pot or just throw in and let them float, look kinda like tiny Water Lily plants:

Hornwort just gets thrown in and looks kinda like Anacharis but more delicate and thinner leaves:

Black Mondo Grass is planted in between rocks:

Creeping Jenny planted outside of pond in soil. They creep into pond and watch them as they will creep everywhere if not careful!:

Ferns just come up everywhere on their own, along the path, in the pond rock edge etc:

Sweet Flag from garden store planted in a pot in pond and that is Azolla a little colorful floating plant to the right floating in a round ring I made out of tubing:

Duckweed just gets tossed in for the fish. Here is the little pond I keep it growing in:

Here is what it looks like close up:

Hardy type Water Lilies, lots of colors to choose from:

Hope this helps!

 

[Sodadispencer]

In my experience, it’s hard to find much actual scientific data about dwell time in a bog. And with the huge variations on the way folks are building their bogs, I think it would be almost impossible to have an exact formula.

I think a bigger issue with our bog is settling time - the water moves too fast to allow fine debris to settle if that makes sense.

I think the intake bay filled with pea gravel I have will help pre-filter a lot of the sediments out. I decided to dig down another foot so I'm within the average recommendations for dwell time.

 

[Sodadispencer]

I'm way up north and way west of you. We might be in the same zone but not sure how cold you get there. Lots of good plants you can grow. I have Parrots Feather, Mare's Tail, Sedges from garden stores, Water Hawthorn, Anacharis, Dwarf Cattails, Floating Hearts, and have had others like Hornwort but for some reason it keeps disappearing, Black Mondo Grass stuck in between my edge rocks w/their roots in the water, Creeping Jenny planted in the edge soil that creeps into the pond, Ferns that just show up on their own, Sweet Flag that I took out as it grew so big it busted out of the pot (looks nice but if you don't keep it small, watch out!), Water Lilies grow great but I took all those out too as I got tired of having to take them out and divide them. I had Azolla but it just went away one day, sometimes I throw in some Duckweed for the fish to eat. I have that growing in a separate small pond. Lots of other plants you can grow that others can tell you about too.

Parrots Feather:
This batch is planted in a big pot so it will not wander too much. I like the red stemmed variety the best as it is shorter and tighter forming and has small feathers.
View attachment 166185

Here is the longer, green stemmed more crawly type, I like it too and some are planted in a pot and others are just stuck in between the rocks:
View attachment 166186

Mare's Tail to the left of photo I found in a ditch up north near Blaine is planted in a pot:
View attachment 166187

Sedges I just found at the garden store and plant them in between rocks also:
View attachment 166188

Water Hawthorn gets tiny white blooms in late Summer or early Fall or Spring when temps are cooler. It's in pots. It will send out seeds that sprout while floating that you can grab out and plant in soil and start more plants:
View attachment 166189

Anacharis is the plants you can find in pet stores for goldfish and if you have a lot the fish may not eat it all and it will grow and multiply enough so they can't wipe it out. I found a wild type growing in a natural pond and collected some as the fish store type seems more finicky:
View attachment 166191

Dwarf Cattails are planted in between rocks. Here is a photo from when I had them in a bathtub pond before I moved them to my big pond:
View attachment 166192

Floating Hearts, you can plant in a pot or just throw in and let them float, look kinda like tiny Water Lily plants:
View attachment 166193

Hornwort just gets thrown in and looks kinda like Anacharis but more delicate and thinner leaves:
View attachment 166195

Black Mondo Grass is planted in between rocks:
View attachment 166196

Creeping Jenny planted outside of pond in soil. They creep into pond and watch them as they will creep everywhere if not careful!:
View attachment 166197

Ferns just come up everywhere on their own, along the path, in the pond rock edge etc:
View attachment 166198

Sweet Flag from garden store planted in a pot in pond and that is Azolla a little colorful floating plant to the right floating in a round ring I made out of tubing:
View attachment 166199

Duckweed just gets tossed in for the fish. Here is the little pond I keep it growing in:
View attachment 166200

Here is what it looks like close up:
View attachment 166201

Hardy type Water Lilies, lots of colors to choose from:
View attachment 166202

View attachment 166203

Hope this helps!

Wow what a gorgeous pond! Thank you so much for the recommendations, I already have a ton of ferns of course but that sweetflag and black mondo grass look amazing too. For the bog I think I'll go with some purple iris and different varieties of hostas. I might have to try out that duckweed too!