Reply To: E-book discretionaries are confusing me

[Robbet]

Thank you for clarifying the sizing, I thought it would be like that but the last wording confused me.

I plan on using the recommended 1:50 slope but I calculated the furthest end as 120mm the plan is then to go down 20mm per meter. I plan on first building the growbed due to space restrictions then digging the fish tank and adding the sand so I’m not sure what sand I am going to use but I’m definitely going to test the sample (I’m even considering buying expensive filter sand if it comes to it).

I’m not sure how I’m going to create the slope though so far the plan is to simply add sand into the growbeds base under the liner and try to have that sand with the correct gradient, my builder recommended I add a line horisontally connected to both sides and then to change the furthest end slope upward. Do you think that would work? I’m not sure how having a sand base is going to stay straight enough when I add the liner and adjust it.

I think trying to create the slit drain like that is above my ability to get right, but since you guys recommend it so much I thought maybe I could add 3 drainage pipes to minimise drainining pressure? Won’t be exactly the same as slit drain but should reduce pressure on sand, the main reason I’m not keen on a slit now is the pond plan is quite a distance from the biofilter and I’m not in the mood to try and figure out how to get the slit to drain so far.

Do you think simply having holes drilled in the cement blocks would be stable enough. I’m honestly not sure how I’m going to get the pipe through the liner without getting some leakage..

I really want to create the best filtration system I can so I’m assuming the main benefit of a slit drain is due to decrease in drainage friction the sand moves less and is thus more stable while also protecting drainage if one section would get blocked somehow?