vk3laj wrote:
Stuart Chignell wrote:
That is a great example of how you can have too big a drain pipe
Its got nothing to do with pipe size its pipe position.
This is only partially true.
In a design where the manifold pipe is on the bottom with risers to deliver water and solids to the GBs settling will occur in the manifold if the water velocity in the manifold is less than the
suspension velocity of the manifold pipe. In such a design the position of the pipe and the size of the pipe contribute to cause settling in the manifold.
In a design where a large manifold with droppers delivers water and solids to the GBs settling will occur in the manifold if the water velocity in the manifold is less than the re-suspension velocity of the manifold pipe. When flow is initiated or stopped the water flow velocity in the manifold can under certain circumstances increase because the flow relative to the cross section of partially filled pipe increases. If this velocity is greater than the
re-suspension velocity then the solids will be swept out of the manifold.
In a design where the manifold size is matched to the flow such that the water velocity in the manifold is greater than the
suspension velocity then settling will not occur and so either configuration (manifold at the bottom versus at the top) can be use and settling will not occur.
So where manifold velocity is greater than suspension velocity position is irrelevant in regards to settling. Where manifold velocity is less than suspension velocity position is very important and an ill considered design will create a design flaw and/or increase system maintenance requirements.
vk3laj wrote:
PS Using a bio filter such as a moving bed filter using K1/K3 filter medium will GREATLY increase your fish stocking capacity, above that of growbeds alone. Do some research on the Earthan website or videos.
This is not entirely true either. Adding a moving bed filter will vastly increase the bio-filtration capacity of the system but will not increase the stocking capacity significantly (within reason) without also adding some sort of solids removal component.
vk3laj wrote:
I've run out of space for growbeds, but want more fish. So solution, add a bio filter after the RFF.
Perfectly valid reason for adding complexity to a system. I taken Paul @ Earthangroup's stuff with several grains of salt. He has a lot of experience but in the past he has pushed the view that soilds removal was essential rather than optional. I stopped being worried about my views being different from his views when he said that the presence of earth worms in a gravel bed was an indication that it was about to catastrophically fail. That is not to say he doesn't know what he is talking about rather that you should consider what he says because some of it is relevant/true and some of it might not be.
Backyard Aquaponics
