Bog filter questions

[Oncorhynchus]

I decided to build a bog filter for my 14 x 6 pond! I am using a 100 gallon stock tank that's about 4 long, 2 high and 2 wide. I'm cutting up a bunch a 2" PVC I have laying around to make a void space about 8 inchs tall. Holes will be drilled all over them and they will stand on end. On top of that a layer of larger rocks, about 3-4" and on that a foot of 3/8 pea gravel. Water will be pumped in via a 1 1/4" pipe with holes that runs the length of the tank with a solid clean out pipe on the other side. Outlet is 2" pvc with an elbow in the tank that aims up towards the top. The stock tank has another drain on the bottom in case sediment builds up.

Anyone seen any issues/pitfalls before I start?

How far below the surface of the gravel should I place the outlet? I was thinking maybe 2 inchs or so marginal plants could keep their crowns high and dry..

Will my PVC pipe void space get clogged up in between the pipes?

Thanks! Any advice is welcome, I'd rather learn now than once it has 200 pounds of rock in it

 

[Oncorhynchus]

Pond size is very approximate...

 

[GBBUDD]

using a stock preformed is not advised ive seen over and over when they fail

a pvc pipe as a drain out from a bog can clog up very quickly i have a 20" weir opening and that gets overgrown and starts to back up.

 

[poconojoe]

I would make it simpler, but that's me. It's up to you.

What you are planning will work and you'll be amazed how well it will filter the water.

I'm thinking I would make it simple and run the PVC manifold directly on the bottom of the stock tank and add pea gravel right over it.
I used river stone. It's a larger than pea gravel. It was all I could get at the time.

I opted for slits in my manifold pipes as verses holes. It seems there would be less of a chance for clogging with slits.

Some like the slits down, some up. I chose up, thinking it would be better if any muck does build up.

You're gonna love the bog. No maintenance is nice. No cleaning filter pads.

 

[addy1]

Mine is very simple, just big. A manifold of pvc pipes, slits down, a clean out drain opened once never again just clean water came out. Pea gravel, plants, water, waterfall back into pond. Works great. Stock tanks do well get a good one. Preform ponds crack. My one small pond is filtered with a flower pot bog.

I would make it simpler, but that's me. It's up to you.

What you are planning will work and you'll be amazed how well it will filter the water.

I'm thinking I would make it simple and run the PVC manifold directly on the bottom of the stock tank and add pea gravel right over it.
I used river stone. It's a larger than pea gravel. It was all I could get at the time.

I opted for slits in my manifold pipes as verses holes. It seems there would be less of a chance for clogging with slits.

Some like the slits down, some up. I chose up, thinking it would be better if any muck does build up.

You're gonna love the bog. No maintenance is nice. No cleaning filter pads

 

[addy1]

I do draw the water from about a foot off the bottom of the pond. Keeps large debris out of the bog.

 

[mrsclem]

I have used stock tanks as a bog. 2 things- go larger with your outflow. 2" is not large enough and the tank will overflow. Also, make sure the tank is sitting on a solid surface. I have had 2 fail because they were up on blocks.

 

[addy1]

Mine are on ground

 

[Oncorhynchus]

Thanks for the info! I'll bump up the outlet to 4" then, better safe then sorry.

The tank is 2' tall and I read you only want a foot or so of gravel/stones, that was my reasoning for the void space. Also to let solids settle out before they get into the gravel. But would I be ok with just dumping 2' of gravel in there?

 

[mrsclem]

Mine has 18" of gravel and stone, all the way to the bottom

 

[GBBUDD]

Yes addy has almost double that in her pond

 

[addy1]

Yes addy has almost double that in her pond

2.5 feet or so deep pea gravel

 

[poconojoe]

Thanks for the info! I'll bump up the outlet to 4" then, better safe then sorry.

The tank is 2' tall and I read you only want a foot or so of gravel/stones, that was my reasoning for the void space. Also to let solids settle out before they get into the gravel. But would I be ok with just dumping 2' of gravel in there?

Be careful of your water level. Using the full 2 feet of depth of your stock tank is ok as far as the gravel goes, but make sure the actual water level is not too close to the very top. You need a little leeway for expansion, just in case. You don't want it to overflow.
The height of your return outlet will determine the water level of the bog.

 

[Oncorhynchus]

Sorry if I'm misunderstanding, but say if the root mass expands, less space is available for water and it would flow out the outlet quicker right? So if your outlet is large enough the only issue would be the water takes less time to pass through the bog?

I may be missing something, hydrodynamics are hard to visualize

 

[mrsclem]

You are correct. As long as your outflow is large enough, the bog will not overflow.