I decided to change the drainage location last minute in my growbed due to bamboo concerns, it is now in the middle. I’m going to mix the soil well and then compact it till this under the drainage holes. The growbed Length = 6.145 and width = 0.98. I plan on having a pond with a 1.5 diameter and a 1.2 depth which hopefully gives 1,100 liters plus freeboard. I’ve already bought a 4×4 liner for the pond. A lot of this is based on a book that has been removed from the official website so I hope my calculations are correct.
The plan is now to have a slope on either sides to the middle where there will be pipes with one layer of shade netting and some rocks. The sides to the closest drainage holes are 260 and 270 is it fine if I have a 6cm height slope on both sides? What would you guys recommend for creating the slope with? Are my pond measurements still accurate for the volume with a dug out U-slope? What sand depth should I have with this system, I do plan on filling it up with more sand but initially I want the recommended depth for a 6m system for comparing.
It would be much better if you just built it the way we teach, especially for your first iAVs. Later on you can experiment with different ideas.
The slit drain does not have to drain directly back into the fish tank (pond), you could have it draining into a pvc pipe with a slit cut into it, and then the pvc pipe can be sent around the side to where the fish tank is located. Doing it like this solves all the problems.
The book has not been removed, there was a course that Gary had run, and all of that was moved into the new book that is still available. All you need to know is the ratios, v:v fish tank volume to biofilter volume 1:2, and v:a fish tank volume to biofilter area 1:6.
Cutting the besser blocks into a slit is the ideal way, pipes are too restrictive, you want rapid drainage in the same way that a sports car has a specialized exhaust.
The slope is 2cm per meter. The minimum sand depth is 30cm, so you can calculate that right?
I recommend reading the 21 page book for refresher.
I would consult a builder or someone with construction or engineering experience and ask them – me personally, I would just keep drilling more holes until there was a slit.
Also, given that it is just a wall, it’s not supporting weight from above, is it really going to affect the integrity of it? A coupe of pieces of metal support (like a grate) would surely solve that.
Another option that I would consider is to get a mallet and knock out a few blocks, create a gap using a support frame, then use mortar to put that section of the wall back together. That would be cheap and effective.
For the slope you can tamp down soil, but if the area is prone to flooding then you may want to consider another support for the base.
A big reason why I opted for the pipes is also because the wall is quite thick making it a lot harder to have water drain out of it while being water proof compared to a 1 inch wall and I didn’t want to deal with that.
That’s why we use a liner……. I use untreated wood, the liner keeps it dry, simple.
I think what I will do is to have the pond in the middle of the bed but instead of water draining directly into it from both ends I’ll have it drain into the far end into a pvc cutter which flows to the pond at the middle of my growbed.
That was my initially plan but due to a last minute location change of the growbed I neglected to consider the new surrounding plants.
I never though of having it drain into a pvc gutter that was very insightful thank you.
Unfortunately cutting cinder blocks would go beyond my power tools, not to mention I think it would risk damaging the structural integrity of the wall (I probably should of this build the gap initially at the start).
Thank you for the feedback I will consider it all.