Backyard Aquaponics
A place to discuss aquaponics

Frank,
timers and siphons are not suggested by me, for the reasons you note.
FFCD needs a timer for obvious reasons.
I was suggesting siphon with cont. inflow... in the top, and whatever you like in the bottom... the siphon output of the top is fast enough for FFCD.

I will try to rephrase what I was getting at:
If using FFCD on top and bottom and cascading.
In order to ensure the bottom is full, the top must fill, then overflow for a suitable period such that the bottom will fill, hence long 'full' time on the top tank.
This I don't like. The sump will also be perilously empty at this point, so the system must be vigilantly watched for evaporation and transpiration losses.

The wackier suggestion I was making, was to do cascaded siphons (such as I run)
don't use a timer, but use a float switch to shut off the flow once the sump is dry.
Then, the minimum sump volume you need is equal to the bigger of the two GB fill volume.

once the first siphons into the second, the pump *may* stop, if it needs to, but the second GB will fill and then drain into the sump, triggering the pump to start again.
This gives a large fudge factor.

Furthermore to address another of your questions: Why is 2 timers bad?
Simply because they are two. They are therefore mutually exclusive, and even nanoseconds of inconsistency will eventually result in both pumps being on at the same time.
Buying a programmable relay or some such would remove this problem.
Or perhaps a switch that switches every time power is applied.

I think this answered your plethora of questions

Agree with Frank on this one.... just use a standard standpipe arrangement on a timer...

Along with piping to all growbeds... with ball valves attached to each growbed inlet (to regulate flow/flood height.....

Simple as.....



Not sure why this is more attractive than the chift pist overflowing to all beds (as above)... or even a single pump (timer controlled) delivery to all beds... with a float aactivated pump in the sump to feed the fish tank....

Simple, easy, works well... as many systems attest.....

Cos his sump size allows for 15 litres or so of evap/transpiration... so I was trying to keep the fudge factor high.
Otherwise I agree too

Even without chift pist, but a timer controlled pump in the fish tank, standpipe growbed drains.. delivering water back to the sump, even during the timer "on" period... and then for some time even with the timer "off"...

Combined with a sump pump that is activated with a "high" point, then cuts off at a "low" point

i.e in reality there's always going to be a certain minimum level in the sump... and a minimum level in the fish tank, dictated by the length of the "timer" period... and delivery back to the fish tank from the float "on" sump pumping...

Basic principle of all the BYAP kit systems.... works reliably.... and encompasses points of failure...

sounds like a good discussion to me ... I did mention that the ST will have a mim. of 55 gallons (208 liters) left when ALL the GB's are full to capacity....but all my stand pipes will be 1" below the gravel and the main GB will be slow draining back into the ST as its filling.

I just have to make sure my pump is strong enough to fill the main GB while its slow draining back to the ST. As the overflow goes into the bottom GB's, they will also be slow draining back to the sump, at a slower rate then being filled... this is where the pump timing will be critical, but if it goes a little long, the water will overflow the stand pipes and not the sides of the GB's it will take some testing to get the right size holes in the SP's but thats what its all about... making the system work...

I am planning on putting 2" foam sheets over the ST to reduce the amount of water loss... also covering the FT because it will be in full sunlight during the day....

I am getting the parts and pcs. I need now and will do so over the winter and start building in the spring...

will post lots of pictures and lots of data on how things are working and what things work and what doesnt..... I will cycle the system without fish until Im confortable with it

thanks for all the good suggestions

Question:

I will have a venturi in the FT fill pipe to add extra O2 to the FT water....

if I put a venturi in the overflow from the FT to the GB's would this help?

also can a Venturi be put into the SP's to add more O2 to the water?

would it work or being slow moving water would it not work?

That is a dangerous question...
I venturi the Sump - FT, the fall from the GB returns airate the water also.

Not really... the flood and drain action supplies the oxygenation to the plant roots... and also draws oxygen into the water as it drains...



Again, not needed... and the holes in the standpipes effectively act (somewhat ) like that anyway...[/quote]

You could put a venturi into the return lines back to the sump... how "effective" (god I hate to say it) or how efficient they may be would depend on many variables...

But the standard models proposed and discussed have been shown to work just fine...

Kuda,
I quoted out of your post only because you mentioned the wet feet,
didn't mean to say that you had suggested timers and/or siphons

we all have made suggestions, most of which involved timers and/or siphons
and these suggestions have become intertwined
difficult to discern who suggested what and where

more, we all seem to take a critical view at our own suggestions
and more than before open our mind to others
good thing and very constructive
this thread is living proof of it

I forgot to mention I dropped the cascade thing
as I too believe that to be only interesting in special circumstances like a terrain with natural inclination

so now (for the moment and on this thread) I am in favor of FFCD, straight to the sump, no cascading

this by itself does not require two pumps: two outputs from one pump will solve it

I believe it has been stated that the volume of the sump will be ample to receive the contents of all the growbeds
so no problem if draining coincides

if not (or to reduce sump volume), two pumps each with it's timer (or a sequencer on the pump's output) will help with that

I agree with you that the timers on these pumps must be related if the sump volume is reduced

but there are many simple solutions to this

which only seem to go out of the KISS principle because they are unfamiliar

one of them is to use one (familiar) standard timer for the first pump with a delayed-off timer (unfamiliar) connected to it.

another solution is repeated by you: a programmable relay

compared to a standard and familiar timer, the reliability of both delayed-off timers and of programmable relays is gigantic

so if one is ready to trust a (familiar) standard timer,
there is all the more reason to trust these less familiar timers,
as they are used for industrial applications everywhere

one will probably have a very hard time to find one of the familiar timers we trust in industry, lest it is connected to the coffee machine

as said, I am ready and willing to help people familiarize themselves with these devices.

they take a cabinet and some wiring, but the result will be professional

none of these solutions (not even the one with two separate timers) deserves to be categorized as catastrophic (which is what I reacted to)

if the volume of the sump is big enough to receive the contents of the growbeds, you can do with two familiar timers.


Rupe,

oooooh... my hair raises (only joking ) when ball valves are suggested on growbed inlets (if these are also the outlets of the pump)
TMO one must at least have one pump outlet running free to avoid pressure buildup and flow reduction

better (and easier to regulate) to have all pump outlets run free
flow can be adjusted with the height at which this outlet is situated

if any kind of valve is used,
I would put it on the growbeds outlet, to regulate draining speed

the advantage of separate pumps with separate timers (related if sump capacity is low) is that frequency can be different from one growbed to another

this should not be considered as a new technique, only as a different application of existing and proven technology.
which gives room to possible optimization.

there is nothing new to it.
indeed many systems attest this to work.

frank

Decalsby, the "dangerous" remark is aimed at me
(which I don't mind, I like my ideas to be challenged)

TMHO Venturi's do not add extra O2 to the water with a positive balance, they TMHO only seem to do so
that is because, to suck in air, energy is needed (free rides are an illusion)
this energy comes from the pump
it is obtained by restricting the pump's exit thus causing pressure buildup
which then is transformed into water velocity differences
which cause a vacuum that sucks in the air

so indeed O2 is injected
but at the cost of flow
this lost flow is no more at disposition for natural aeration, which can be enhanced in many ways (open gutters, cascades etc...)

as all energy conversions mean loss of efficiency, I cannot imagine the balance to be positive

I must quickly add to this the three exceptions in which I think a venturi is a good solution as somebody pointed one of them out to me:
that is to reduce sound
freely cascading water in open gutters produces more sound than if the water is contained within tubes
there a venturi is probably a way to increase O2
but one must realize that this costs energy

the second exception is if your purpose was to use a pump only for aeration
I believe that to be a better solution than a blower, but for the above reasons, venturi's on the outlet of the pump not to be the best solution
I'm not sure about a venturi on the pump inlet.

I have lost my line of thought (am getting older)
so I cannot remember exactly what the third exception was

there is a positive side to my alzheimer:
it leaves room for anybody else to suggest an exception

frank

I forgot to add:
I absolutely agree with Rupert that no extra O2 injection is needed in a well designed flood and drain system

frank

Think the third exception was heat/cold, transfer and water loss on a return gravity feed using gutters

I think the third was a venturi on the outlet from a GB. It is a free ride with no extra cost in power or stress for the pump. Very efficient and the only cost is a bit of PVC. Gets left out a lot because it weighs in more on the pro's of venturi for adding o2.

Sorry thats what I meant
The above was why some of us prefered to put a venturi rather than gutters.

Hey all....

im back from my vacation in PA. spent a week and was bored LOL....

jT