Backyard Aquaponics
A place to discuss aquaponics

Hello all,
I am wondering if anybody has used drains in their growbeds that are completely hidden under the growing media, ie perforated pipe or well screen lying horizontally on the bottom of the growbed. Do all drains need to be periodically rotated, shifted, (spun) to ensure good drainage? If anybody has knowledge of different gb drain systems and knows the "best" drain that is low maintenance please advise. My growbeds will be 12' x 4' x 3' deep. Does anyone have experience with gravel growbeds this deep? I am currently building a prototype gb so I will be happy to try any recommendations.

Wow! 36" deep for a grow bed! You plan on growing trees? That is deeper than most. Anyway, if using eb and flow it is best to have some sort of access to the stand pipe for mainenance and it is a good idea to periodically twist the outer pipe to cut any roots that may grow through the perforations. However you can lightly bury the pipes with gravel provided you cover the outer pipe with a cap. I fear that the normal Auto siphon will be a bit of a challenge with the GB being 36" deep. The tail end of the siphon will have to be significantly lower than the bottom of the tank to maintain a siphon when the water is lower. It is a challenge but not an impossibility. Let us know more about what you are doing to be able to help.

For a bed that deep, it would be rather difficult to reach down even a big stand pipe to grab any leaves or gravel that happens to fall into the drain. I don't think I would go any deeper than the length of my arm and make sure the mesh pipe keeping the gravel back is large enough to allow my arm and fist to pass.

I don't have the "double outer pipe" thing going to be able to twist to cut off roots, I just reach down and do it by hand.

I suspect auto-syphons could still work just fine provided the fall below the grow bed for the drain was adequate. I don't think the depth of the grow bed makes much difference in this matter (I've actually had more trouble with extra shallow growbeds.)

I do have a barrel ponics system with some perferated pipe in the bottom around the drain and no standpipe access at the surface. I suppose this is ok for small beds but for large beds I would definitely want access to the drain system so a small problem doesn't cause the entire bed to need emptying.

As to the absolute "best" drain system. Well that is difficult to say since there is the "it depends" part of the answer. For it's clockwork reliability I love my Flout, but it takes up a fair bit of space in the grow bed and a Flout to empty a 3' deep grow bed might not work so well. Flouts have the benefit of not being picky about flow rates (so long as the inflow does not excede the drain plumbing.) Loop syphons have been pretty good to me but you need to size your syphon appropriate to your inflow rate and the flow rate of water through the media does play a part in autosyphons. Bell syphons have the benefit of being all internal to the beds but require some tools to build and adjust them, they can be a little picky about flow rates but they are easier to install tricks like breather tubes and once running well are pretty easy to maintain.

So, why are you planning on 3' deep grow beds?

4' Deep grow beds. Timer, 15 min on, 1 hour off. Standpipe, no siphon.

Siphons are the best I reckon, but I dont have the fall available from these beds.

Are you making the GB's this size for a reason or utilizing something. I like the deeper GB's for the surface area they provide for the bacteria. If you want something on the bottom of the GB is an access panel viable.Eg PVC extended out the side with a screw cap on one end.

My GBs are 3' at their deepest and I let water into them via 100mm slotted ag pipe which runs down one side of the full length of the 50' GB. There is a 2nd 100mm slotted ag pipe on the other side connected to the siphon that drains each GB.

Can't give you any comments on the effectiveness of this setup because its not been 100% commisioned as yet.

Stuart.

PS the reason I have deep GBs is so that I have a higher volume of GB to surface of GB ratio. The extra surface area for planting will be made up by a NFT setup.

Hi, I am planning to build the growbed from concrete. It could be less than 3' deep but I would like it to be a comfortable height to work at… I could use a cinder block stand to get some height but if the extra gravel is going to do more good than harm (can you have too high a gravel to culture tank ratio?) I'd just as soon put the bed directly on the ground and increase the depth a bit. I am planning on using a 4" perforated drain pipe lying on the bottom of the 12' long bed, saddled into a vertical 8" perf with a bell siphon inside. I was even wondering if it would be OK to use a bell height that leaves 1' of water in the bottom and only siphoning off the top two feet, but from the bottom so the water is changed at every cycle. Also I am planning to have to aeration lines (leaky tubing) running parallel to the 4" drain several inches away from the pipe. Any experience with using aeration directly into an aggregate growbed? Last thing, for my horizontal and vertical perforated drain pipes I would like to try slipping two close fitting perforated pipes together, one inside the other, keeping the external perf pipe with larger holes static and rotating/ remove clean and replace the inner pipe periodically to help clear roots etc. Has anybody done this or anything similar?
I am attaching a .jpg of the system I am designing as well as the gb to help you visualize what I am describing.
Thanks all





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Have you thought of other configurations for the layout of the GBs and for that matter the FTs.

The layout that you have drawn may give you really good access to every bed but it looks like it takes up a lot of space. If you have the expertise to build the GBs why not the FTs as well so that you can make them rectangular to save space?

What sort of system is it? CHIFT PIST? Do you have enough fall to get the water to drain from on the ground beds to the sump?

I don't know if I would intentionally try to leave a foot of water in the bottoms of the beds. With a continual running pump, the bottom level of a bed will never be dry as the syphons shut off and the bed is already re-filling. If you do leave lots of water in the bottom, air is probably a good thing if you want the gravel down there to support bacteria well but how are you going to access the air tube to check it, clean it and replace it when it clogs up? Air stones and air pipes do require maintenance and under that much gravel you have no way to really know if it's working. Perhaps you would need a perferated pipe running down from the surface and along the bottom of the bed so you can fish the air tube in and out when needed.

The pipe in pipe is a good way to help clean the roots out but be careful those roots won't just do down the drain and make a clog somewhere else.

I notice your design seems to have a trapezoid shape. I have found that it can be really tricky to balance the inflow with an auto-syphon on a half blue barrel cut the long way because of the changing volume by level. Definitely test one out before you build a huge greenhouse full of them to make sure you can get things balanced.

I kinda like the idea of having your extra bio-filtration in the bottoms of the deep grow beds to allow for NFT or other growing methods. Just remember to search for the drawbacks so you can fix the problems before you have big heavy grow beds filled with so much gravel.

Just something to keep in mind, it will take lots of gravel to fill those grow beds going all the way to the ground. Do you have a good source for it?

As to the round fish tanks. Round makes for slightly easier solids removal as well as a curve is always stronger than straight sides all other things being equal a circle will contain more area wile using less material to contain it so there is a cost savings there as well. The drawback is that some bits of space is wasted around the corners and it is more difficult to divide up a round tank than it is to put dividers in a rectangular raceway. Being able to slide a divider along in a rectangular race way can make harvest easy as well as dividing up and grading fish. So, ya gotta figure out which points are more important and by how much to help you decide.

good luck, looks like an ambitious plan there!