Raised Pond vs Raised Bog Filter - Is the same pressure exerted on the walls?

[LennyM]

Hi! I'm new to the forum and to the world of ponds. I've learned plenty already just from reading many of the posts. I live in Thailand and am building an in-ground pond and a raised bog filter. My initial question is about the amount of pressure exerted on the walls of a raised bog filter vs a raised pond of the same size. The pond has the weight of the water pushing against the walls. The bog has lots of rock and much less water, and also has water running out the top. Does the rock in the bog mean there is more or less pressure exerted against the walls? Does the water running out the top reduce the pressure on the walls?
It might help to explain why I'm asking. I have a lot of 2 x 4s available for free to build a wood frame for a 3 m long x 1 m wide x 60 cm deep bog filter (10' x 3'3" x 2'). I can find many examples of wood frames being used for ponds of that size, but I don't see any bog filters of that size made with wood framing. So I'm sure I could build a wood frame strong enough for a pond of that size, but would it also be strong enough for a bog filter of that size?

 

[JRS]

Welcome to the forum. Solid rock weighs more than water but not sure how much difference it would make. Could you double the 2x4s for a safety factor?

 

[j.w]

@LennyM

 

[LennyM]

Welcome to the forum. Solid rock weighs more than water but not sure how much difference it would make. Could you double the 2x4s for a safety factor?

Thanks JRS. The rock definitely weighs more than mater; but, in my mind at least, it seems like most of the weight of the rock is down into the ground and not pushing on the walls. I could easily double the 2x4s, and its hardly more work, so that's a good idea. Thanks.

 

[Mmathis]

Hello and welcome!

 

[GBBUDD]

a bog full of stone has a great deal less pressure than is water pushing against the walls. like you said most of gravels pressure is downward. But it tooo pushes against the side but holding back a three foot high wall of gravel is possible with a level wall held back by a man. change that to water and theres not a chance of holding back more than a foot and thats multiplied as by the length of the area as water will all flow out above that point unlike stone that will simply stabilize it's wall in a pyramid.

 

[addy1]

Welcome to the forum!

Post pictures as you go.