Completely (80cm) submerged bog filter - worth it?

[HannahZ]

Hello,

First of all, thanks to anyone reading this who helped to make such an amazing resource - this forum is incredible!

I have read up a lot about bog filters, both one this forum and elsewhere, and am building a conventional one at the top of my new fish pond. However, I also have a space in a pool downstream which includes a large, submerged, ring-shaped channel that I am anyway planning to fill with gravel, and I wondered whether it was worth adding a manifold to it to increase the amount of bog filtration?

The problem I'm stuck on is whether it's worth trying to build a bog filter with the handful of plants that can grow that deep. The ones I have available are:
- Hornwort
- Starwort
- Spiked Water Milfoil
-Water Crowfoot
- Willow moss
- Marestail
- Water Hawthorn
I also have lilies, but I understand adding them to a bog filter is a Bad Idea, and anyhow I don't think they'd like the waterfall in this bit of my pond.

So my questions are:
1) Has anyone here successfully made a deep-water bog filter?
2) Does it seem likely that the plants above might be worth using in a bog filter context?
3) Does anyone have ideas for other/better plants that can grow rooted at 80cm below water-surface and will cope with Southern UK conditions?

Thanks in advance to anyone who has thoughts and makes time to share them with me!

 

[j.w]

@HannahZ
I don't have a bog, wish I did!

 

[HannahZ]

I've found a few more pond plants to add to my 'deep water bog filter plants' list, in case that affects anyone's opinions:
- Persicaria amphibia - Amphibious bistort
- Nuphar lutea - Brandy bottle
- Orontium aquaticum - Golden Club
- Nymphoides peltata - Fringe Lily

So it's looking a bit more promising, although I'd still very much value opinions!

 

[Rugar458]

Deep is nice until it's time to clean them out. If they are designed with a well planned clean out system, then life can be good.

 

[dinm]

Hello,

First of all, thanks to anyone reading this who helped to make such an amazing resource - this forum is incredible!

I have read up a lot about bog filters, both one this forum and elsewhere, and am building a conventional one at the top of my new fish pond. However, I also have a space in a pool downstream which includes a large, submerged, ring-shaped channel that I am anyway planning to fill with gravel, and I wondered whether it was worth adding a manifold to it to increase the amount of bog filtration?

The problem I'm stuck on is whether it's worth trying to build a bog filter with the handful of plants that can grow that deep. The ones I have available are:
- Hornwort
- Starwort
- Spiked Water Milfoil
-Water Crowfoot
- Willow moss
- Marestail
- Water Hawthorn
I also have lilies, but I understand adding them to a bog filter is a Bad Idea, and anyhow I don't think they'd like the waterfall in this bit of my pond.

So my questions are:
1) Has anyone here successfully made a deep-water bog filter?
2) Does it seem likely that the plants above might be worth using in a bog filter context?
3) Does anyone have ideas for other/better plants that can grow rooted at 80cm below water-surface and will cope with Southern UK conditions?

Thanks in advance to anyone who has thoughts and makes time to share them with me!

It depends on how wide your bog is. Hornwort easily grows 3ft, right now I have it at almost 3ft in my pond, and has almost reached the surface and my pond is under a tree, gets dappled sun in the morning. Though I don't understand, is this just a regular bog you have or a bog as a filter?

How would a deep water bog filter work, I have a bog but ive been under the impression that gravel is what powers the whole thing, without it there are hardly any microbes?

 

[HannahZ]

Deep is nice until it's time to clean them out. If they are designed with a well planned clean out system, then life can be good.

Thanks for this - if I go for it it's a great tip to be extra careful with the clean out system here.

 

[HannahZ]

It depends on how wide your bog is. Hornwort easily grows 3ft, right now I have it at almost 3ft in my pond, and has almost reached the surface and my pond is under a tree, gets dappled sun in the morning. Though I don't understand, is this just a regular bog you have or a bog as a filter?

How would a deep water bog filter work, I have a bog but ive been under the impression that gravel is what powers the whole thing, without it there are hardly any microbes?

Sorry, I probably wasn't clear enough. I'm talking about a hypothetical bog I'm considering adding in addition to a conventional one. It would be built exactly the same as a normal bog filter - with a slitted manifold pipe covered in gravel, so hopefully still home to microbes. Water would be forced into the pipe and through the slits into the gravel and plants would be rooted in that gravel and hopefully take up nutrients in the same way. The only difference would be that the space I'm considering doing this in is at the base of an 80cm deep pond - so the planting would have to be of specific deep-growing plants. I've never seen anyone talk about having that much water above a bog filter - I know there are people with very deep gravel layers in their bog filters, but that's different from what I'm suggesting in that the planting of such deep-gravel bog filters is still done at normal marginal planting depths.

 

[HannahZ]

I'm much better with pen and paper than digital drawing, but it's what l had to hand and hopefully helps make what I'm proposing a bit clearer!