Backyard Aquaponics
A place to discuss aquaponics

Nice stu

I've got a question to throw at you all. EB your opinion would be valued too, as you're the one with the most experience.

I'm seriously thinking of picking up a couple of those troughs, and i've convinced a mate to set up a system, so we'll get 4 and hope for a discount

Any-way, the question: For a flood and drain set up, is there a specific need to have the water distribution pipes evenly spaced over the grow bed, or even there at all? If i was to flood the bed to within say 5cms of the top even seedlings would "get their feet wet", and bio-filtration would still be happening. I'm thinking of pumping the water in one end of the 2.4m trough and having the stand pipe at the other end?

Opinions / experiences would be appreciated

The way I have my bed set up at the moment the water is coming in at one point, albeit about 40 x 30cm wide, and then draining at the other end (using flood and drain). Of course this has only been going for a few days so I have no data as to what will happen long term. I expect the main issue would be build up of the bigger solids in the one place. Smaller solids would be distributed by the water action. Because my big bed is filling after going through the small bed, any issue with concentration of solids will be in the small bed and could be easilly dealt with by giving is a clean now and again between harvests of fast growing crops like lettuce.

I don't think that there needs to be as much gridwork as I have on my system, I feel that the gridwork can definately be cut down, however, as VB mentions, I think you do need water going into the bed at a number of places to spread the solids around a little... This thread might need to be split into a new topic.

I have just a square grid on top of my gravel. Hopefully this will do the job of distributing solids evenly. This was born via how expensive 25mm preessure pipe crosses are compared to elbows etc

I have used both flood from below surface and trickle tube to almost each plant site.

My small garden with only one entry point is doing well, I see no difference in distribution of nutes in this garden. But it's only 650 x 400 approx size.

On a 2.4 length I'd be inclined to add at least 2, perhaps 3 intakes - at 600, 1200, and 1800. I already know one intake will do 650...

Alternately you could experiment with only one, having your heavy feeders on the intake end.

We can lose a lot of piping yes, but how much?

I have abandoned the pipe down the length of the bed in favor of water spilling in at the top of the bed and just trickling down the length with plants on each side of the "stream." It actually looks like a natural creek. Oh and My lettuce is doing fine. But I think solids are not getting dow to the other end cause plants down there are smaller.

How long is the bed and at what distance do you see smaller plants michael?

the bed is ten feet (3 meters) long and 2 feet (.6 meter) wide. the plants start decreasing in size half the distance down (about 1.5 meters). Not a huge difference, but noticeable.

Nice! 1.5 it's noticeable. OK.

I think to create overlapping fields of fire and 1.2 being a standard big bed width and building measure....

The entry point would encompass 1.2 metres in each direction, were the flow rate to equal by scale the rate michaels 0.6 bed is filled or flows through.

I think it's safe in 1.2 width bed to have an entry point in the centre every 1.2 metres. In .6 bed just run it down the side if you like.

Most excellent find.

What are the plants in the system michael, light feeding, heavy, or mixed?
And the flow rate?

Flow rate into the bed is roughly 60 gallons per hour continuous with 120 gallons per hour surges every 15 minutes.

Plants are butter letuce, basil, and wildflowers. All doing great. In fact last two days, basil (at the far end of the bed, just took off and doubled in size)

Thanks guys, lots of good info

Do you suffer from algae build up on the surface of the gravel MF? I get bad algae if I don't keep the water away from the surface of the gravel..

I think that provided the flow rate is a reasonable volume, the likelyhood of all nitrate being stripped from the water from when it enters to when it leaves the other end would be unlikely, paritcularly if running reasonably high concentrations of nitrate. After all water is continuously entering the beds (at least until they are flooded - by which time you would expect an even distribution of nitrate amongst the flooded bed). Maybe I'm hugely wrong - but this seems logical to me.

Wouldnt it make sense to use a grid formation for "even" distribution of solids and nutrients?

I think I read in another thread on here that someone was using unusually long grow beds and there were comments about the plants further downstream receiving less nutrients.

I know we would all be using smaller growbeds than that discussed in the other thread but even spread of nutrients would be beneficial wouldnt they?