Backyard Aquaponics
A place to discuss aquaponics

you need a much smaller sump if you sequentially flood your growbeds
if you do that, the smaller your growbeds, the smaller the sump
you can achieve that either with valves or with small pumps, one for each (group of) growbeds
and timers or a small programmable relay

frank

+1 Rupe ,, but kw/hr

I think the difference is that a more powerful pump shouldn't need to run for as long, hence the 20 minutes rather than an hour that I'm using (and that Rupert is working from)

I understand that I'm unlikely to get the stated output accurately in the real world, but in order to compare the different pumps I'm just assuming that they're all equally innaccurate

I order to ensure that I'll have enough power to do what I need I'm allowing an extra half-meter of head. (and then oversizing the pump anyway)



That's true Frank, but I'm trying to make the system as resilient as possible - with as few things that can go wrong. Also trying to minimise the problems from any failure - hence a sump big enough to hold all the growbed water.

Andrew, please read my signature
you are right in assuming that most pumps are equally inefficient
which is why we must put them to optimal use

TMHO most AP systems waste a lot of energy
as flooding and draining continuously is by no means needed
and could even be detrimental to (most) plants growth and root health:
not all plants enjoy constant wet feet

look at nature:
flood and drain corresponds with rainfall, which occurs irregularly and unexpectedly
or with the tides which go with the moon, so twice a day

TMO you will obtain far healthier root systems
you will train your plants to root more deeply (proven)
which makes them less vulnerable
the roots will be better aerated

with sequential flood and drain you need a much smaller pump
and a much smaller sump

here is my favorite setup, which I also consider as very simple:

the fish tank overflows and cascades (= aeration = healthy bacteria)
into either a biofilter or a first "wet" growbed which drains into the sump
this ensures constant biofiltration
I grow watercress in this growbed (can hardly keep up with it)

I locate the sump right under this first growbed which means no space is wasted
from there the pump pumps only straight up to a horizontal open gutter located just above the rim of the fish tank

the very short slightly over dimensioned standpipe (+/- 1 m)
ensures minimal pump head so maximal flow for the energy invested
and for two reasons better and free (!!!) aeration: the open gutter and the maximal flow

the gutter is forked
on one side it leads back to the fish tank
on the other side to the growbeds
part of the water continuously returns to the fish tank, cascading into it
thus ensuring constant aeration and fast solids removal (less need for aeration)

each (set of) growbed(s) has a valve for fast flooding
when full to the required level an overflow returns the water to the sump
when the flooding valve is closed, the growbed slowly further drains into the sump
the roots are well aerated and so is the water

the valves (unless there are many) can be manually operated

with all the valves closed, all the water automatically returns to the fish tank:
more (free !!!) aeration, more solids removal, more biofiltration
healthier fish

I don't use gravel: it is heavy and retains no water
I use Argex expanded clay pellets (hydroton) perlite and vermiculite (these can be mixed into gravel)

by using moisture retaining media, the risk that a growbed ever dries out is minimal
even if you skip a day
this very often happens in nature and the plants grow stronger for it

this sheds a new light on automated valves
should one fail, there are very little consequences

my next step after some months of experience:
Argex expanded clay pellets (hydroton) are my to favorite medium:
I have remarked that part of them sink, part of them float
which at first seemed annoying
but can be turned into an advantage:
I will separate these
spread a thin layer of sinking pellets on the bottom of the growbed
I plant my vegetables in square pond baskets in sinking pellets
place the baskets on the thin layer
then add a layer of floating pellets in the growbed

with each flood, these pellets raise with the water
with each drain, they fall back down
thus forming a self cleaning fluidized bed biofilter

now you know all my secrets

frank

Very difficult to visualize from only text though Frank... Pics would be nice..

Nice to see you back... and with more detail regarding your system Frank...

Must admit I haven't checked in on your site and system progress for while...

But I still... IMHO.... am to be convinced that some of your "assumptions" and "interpretations" are correct...


Partly correct... some plants definitely... by soil gardening lore... appear to dislike having "wet feet"....

But I believe that what they actually dislike.... is the lack of oxygen that saturated or slow draining soils cause....

A case in point is rosemary.... which everyone says hates water... but which is thriving in my flood and drain system...

And the reason that plants that have been submerged or saturated by heavy rain... often wilt... and why it is recommended that you should water after periods of heavy rain...

Because the sitting water has become depleted of oxygen....



Some plants root more deeply by nature....and/or will send down tap roots in search of water... many will also do so in good friable soils, which by nature drain well...

Again I contend that this is actually more to do with oxygenation.... and it's the lateral roots of plants that provide oxygenation... not the tap roots.... the reason that NFT works, and the root structure it provokes...

Secondly... flood and drain is not just about oxygenation of the plant roots.... but more importantly (or just as importantly)... is about oxygenation of the nitrifying bacteria... and water returning to the fish tank...

The number of flood & drain cycles are just as importantly moderated by the need to turn over the tank volume and provide filtraion... as they are for plant growth.... and in the highly oxygenated root systems developed by flood and drain... watering periods are somewhat inconsequential... in terms of too much... other than as a function of ambient temperature...



Not what I would call simple... but heh.. if it works then fine...



It's certainly heavy... and drains with little water retention... but again I think you miss the point.... water retention (other than in extremely hot climates) ... isn't what it's about...



Which may well work in your climate Frank... but believe me... a day without water in the middle of an Australia heat wave... is a different story...



Interesting... most hydroton we get... hardly floats at all... other than when initally wetted.. but settles within a few hours...



Well actually Frank... the majority of any solids and suspended matter wouldn't be in the "floating layer".... but deeper in the bed... so IMO... the concept that they are "self cleaning" is somewhat mute...

Would love to see you start a thread here on the forum Frank... so that we could all follow your progress and results...

We might learn something...

Thanks Frank, very interesting. I'm particularly interested in the aeration that this provides



is this not just a standard pipe then ? is it more of a waterfall/open cascade to agitate the water as much as possible? I'd love to be able to do without an extra aeration system.



How are these beds draining frank? presumably with siphons?



would Coir be better for moisture retention possibly? Would love hydroton - got to check out the prices for 4300 litres of it!

Not quite sure I've understood everything you're suggesting - I'll go and have a look at your site to see if it all becomes clearer :-)

Consensus of everyone that's tried it... is coir just remains too wet in an AP setup...

As a drip feed.. once every couple of days... style of arrangement... and run to waste... great...

Remembar though most coirs have... and will retain your pH around 6.0-6.4 .... some coirs can even be pH 5.6-5.8...

Rupe ,, just so I'm exactly sure what we are talking about ,, the REAL coir as in loose packed LONG fibres like a birds nest ..... NOT the stuff you buy in bricks at Bunnings?

No worries - think I'll give it a miss until I know what I'm doing (is that point ever reached . . . )

Have just been looking at prices for Hydroton, seems to be cheaper when it's called LECA, which I'm assuming is the same stuff.

It's incredibly pricey by the 50l bag - 40p/litre (surprise surprise), but if you get it delivered in 1200l open bags then it drops to only 7p/litre - plus delivery - so *only* 350 quid for 4300 litres of the stuff.

Then I just need a crane to move them around . . . . . .

hmm. Just realised I'm going to be washing and moving nearly 2 tonnes of hydroton around. Time to buy a new wheelbarrow.

Most predictable reactions.

I do not have the time to waste in another yes/no discussion, unlike apparently some others.
That is exactly the reason for my silence on the forum.

I took a painstaking two hours to write my last post, taking the greatest care to explain my system clearly and simply, wishing to share my views for all to enjoy.

... or to reject. Be my guest.

Reread it, let it rest, do some sketches on a piece of paper and it will all become clear.

In fact I will post it on my website as is.

For those who STILL want proof of the fact that I do have a respectable setup
goto:
http://www.aquaponics.eu

there are lots of pictures and explanations and more to come when I have the time

frank
P.S. I am right now designing a passive greenhouse of which I plan to build two
so it might be interesting to take a look now and then:
http://www.aquaponics.eu

All sorts available Chappo... blocks, chips, chunks, fibres... tried them all... got a heap of blocks left over...

The husk fibres are quite good as a seed or seed plug starter medium in net pots for NFT...

P.S.... be wary of those Bunnings blocks.... many of them have been soaked in a fertiliser additive....

Well the last page raises some interesting questions.
In an NFT system a plant creates water and air roots
In a DWC a plant creates water roots
What does a plant create in a Flood and Drain system given that people are F and Draining at different intervals?

Sorry for the Hijack Andrew

Both. But the water roots would be the main ones that head for the bottom of the gb's. You get a pause with new seedlings when you first plant them and they have to grow new roots first.