Backyard Aquaponics
A place to discuss aquaponics

I am thinking of making some hardwood growbeds for home. How about a list of what people like about their growbeds. What size and shape do the find to be the best and why? If you could make a growbed any size/shape you wanted what would it be and why, what extras would you add to it?

My ideal grow bed is half pipe shaped ,, like those in the South Africa build , but made from stainless steel. A small inverted half pipe made out of mesh would allow easy solids flushing when needed.

I like growbeds of about 3 foot wide or less (provided you can access them from either side, if they can only be reached from one side, I'd go narrower as I don't really like reaching too much.) I think of 12 inches deep as a minimum for normal grow bed operation. I do have one that is only about 7 inches deep and it really isn't as effective as I'd like. I think extra deep (like 18 inches to 24 inches) grow bed might be very worth while especially if you wish to add other types of growing methods after the grow beds (like NFT, DWC or towers.) Deep grow beds would also be good for growing small trees or long lived perennials with big root systems.

As to length of growbeds, most of mine are 8 foot long, that is convenient as 4 x 8 foot sheets of plywood are easily available around here. I do however have one grow bed that is between 28 and 30 feet long, that one is simply liner on the ground with a rail of wood to hold the top edge and stakes pounded in to hold the lumber in place. That monster grow bed works well and I'll probably design future systems with a gravel filled sump like this.

When you ask about extras, what do you mean?

Any fancy drain holes or open drain ends with mesh to hold back media and such things. Sloped bottoms maybe? Just things that people have done that have worked and they would do again or improve on. Outcome may be that the best option is just a rectangular box without any of these - KISS

Most of mine are the simple rectangular box. For putting uniseals through one might want a small section of thinner material because pushing a 1 1/2 inch pipe through a uniseal through a 1/2" plywood is really difficult.

for the on the ground monster bed, I made a slight sunken area in one end for the sump pump to allow it to drain the bed down a bit better. Otherwise, I don't think sloped bottoms really buy you anything and if you get too extreme (like half barrel cut lengthwise) in the shaping, you might make it really difficult to get the auto siphon balanced just right.

One note about the lumber grow beds, gravel and water exert a lot of force, my plywood and 1x4 grow beds are starting to bow out on the sides a bit now after a year or so in operation.

My vision is from a commercial point of view. My ideal grow bed would be one massive bed made of concrete, enclosed in a greenhouse for year round production. It would be sloped slightly from front to back with a depressed area around the drain area. A minimum of drainage locations, even if that meant larger piping, which would reduce maintenance and clogging issues. Stainless steel caging to keep back the gravel as it would need to be strong and fish safe. The gravel would be smooth, 1/4" to 1/2", whatever would work for ease of planting and tilling. Probably 16-18" deep but that would be dependent on the equipment used to maintain the bed as that would be mechanical and operate on electricity, custom made with stainless steel tines. (Don't laugh, a farmer in California has a full size stainless steel harvester to harvest baby spinach in the open fields, for those pre-packaged packs in the supermarkets.) Water delivery would be overhead or portable so it could be moved out of the way for maintenance issues. Drawbacks are that it would be walked on but most professional greenhouses have sanitation baths to dip your shoes in before entering, same with aquaculture facilities. I would probably have an employee uniform that included dedicated footwear.

That's the ideal grow bed but that is not the end for me. This grow bed is only a pre-filter for the DWC that operates a conveyor style production of greens. From there, it's back to the fish tanks and starts all over again.
Currently I'm building my system and it does have a single large gravel grow bed for trialing just such a system.

Nice plan Angie....

A couple of concerns related to the idea of "overhead watering"..... particularly as they are intended to act as pre-filters to UVI style raft beds...

How do you intend to prevent the sprayers from becoming clogged either by solids or by the growth of bio-film...

How do you aim to prevent algae growth on the top of the gravel beds...

What sort of evaporative losses do you think you might incur....

And how do you envisage flooding and draining the growbed(s) sufficiently to draw the oxygen down through the media for both nitrification and plant growth...

I'm not sure if your intention is to maintain a continuous or intermittent overhead "spray"... which you then collect to a sump and punp to your raft beds....

But regardless... I have some lingering doubt as to how you are going to acheive a fill (flood) of the growbed... both within a timeframe that benefits the plants and bacteria.... and acheives turnover of tank volume...

I'm also concerned as to the affect that constant... even if intermittant overhead watering will have on your plants... particularly some varieties like tomatoes, cucumbers and others that don't like overhead watering...

And the promotion within a high temp, high humidity greenhouse environment of fungal and other diseases...

Rupe, I don't think Angie is actually planning "overhead" overhead watering like with sprayers or sprinklers. I think she described something more like a troughs that can lay out on the beds and be fed by flexible tubing and these troughs would overflow through notches into the grow bed. Kinda a distribution grid without the holes to clog up that is easy to pull out of the way for harvest and cleaning. I expect it would still grow a fair bit of algae but there may also have been mention of covering the troughs with panda plastic (though this might get a bit niggly if it has a tendency to come loose when shifting things or whatnot.)

Personally, I'd probably skip the distribution gutters in favor of simply laying the flexible hoses in a few places on the beds and shifting them around if/when a particular spot starts to get gunky. My beds have been doing ok with the single inlet point even though I think I may be running the edge of stocking density and solids handling.

Ok... that makes more sense... couldn't see how all the potential problems could be addressed using "overhead" watering...

Think I agree with you though... why bother with a trough... just use a distribution line along/into the growbeds... it can be kept clear of bio-film with a short burst of pressure once a week/month...

My concept of "overhead" watering is obviously quite different...

What you're proposing, and I agree with... might be better referred to as "inline irrigation"

I plan on milling some 200x50mm hardwood for the bed construction or maybe 150x50 will depend on log availability and final growbed design and depth . Either way it won't be going anywhere in a hurry.

As far as uniseals go I was thinking of drilling an oversized hole through the main timbers and them placing an appropriately sized washer of ply over that hole to mount the uniseal in. Might even get real fancy and route out the washer overlap section in the hardwood so the washer sits level with the hardwood.

If you are gonna go to the trouble of building special grow beds, make sure to have them deep enough. Except for very rare situations, I definitely think 30 cm or more is a better depth than less. I'm actually thinking 40 cm might be more perfect for anyone likely to add in other growing methods after the grow beds (like NFT, towers, DWC etc.)

I find it interesting when someone throws an idea out, how everyone interprets it. I need to clarify what I mean by "overhead water". First, let me say that I would never recommend sprinklers for plant areas, although larger fire hose types may have their uses in other places.
There are two ways to introduce water into the grow bed area- a header pipe which then splits off into smaller pipes or troughs (in my case) but the other way is an overhead boom, similar to what is used in commercial greenhouses for watering. You would still need a smaller delivery system for the individual beds, which could still be portable- but if you used a boom, instead of a header pipe, you would remove a large, permanent and stationary object from the grow bed area. The concept is to make the grow bed area completely accessible and versatile.

As to the troughs, any time you break water tension, you introduce oxygen- the water will lip over the top of the troughs and splash down to the gravel below (a brief free fall) and the panda fabric will help as well, not only as the water trickles along the inside but with recaptured evaporation that will run down the sides again and again. However, if oxygenation is required, the troughs are in essence shallow water-filled tanks and bubblers could be placed there.
The prototype will tell me how advantagous using troughs will be- it is an unproven concept at this time but I do believe it has great potential and may replace traditional pipe grids or single inlet piping, not only for it's portability but other advantages as well- evaporation control, earth worm protection, water delivery, introduced oxygen, heat control (panda fabric is reversible from white to black), introduction area for extra oxygenation, if required. Of course, the potential drawbacks are how convenient will it be to move, will it attract too much mold and other negative side affects, leave too much gravel dry and thereby make an inefficient bio-filter. Some of these issues may be allievated with simple solutions, others may not but having an active system at full operation is the only to prove it's potential.

... just when I thought I was beginning to understand your model ... you throw up something I hadn't envisaged...

Can you post up a drawing of your "boom" Angie.... I'm struggling to understand just how you are delivering your water supply to the big pre-filtering growbeds... draining them... and just what sort of flood & drain mechanism and timing(s) you are proposing....

I'm not sure I understand why a run of piping along the media surface to deliver nutrient water is such an impediment to access... or a substantial waste of space??