Backyard Aquaponics
A place to discuss aquaponics

Nup... I have never worked on that rule....

By big system at home used to only pump about 1/3 of it's volume every hour.. viewtopic.php?f=18&t=1360

But as a general rule of thumb for those with no idea trying to work out a custom system, there's no harm in following the idea of 1 tank volume per hour..

EB, your system which turned over 1/3 of the volume per hour. Was it lightly stocked with fish?

Not really.. Grow a crop of over 90 Barra in it, then Silvers, can't remember how many there were in it, here's a pic..

Terrible water quality there EB. Are you sure you know what your doing?

I am SO confused!!

I bought a pre-made bell syphon, 4000ltr/hr pump and a cut up IBC.

What do I do? syphon, f&d or continual flood???

Do whatever you want.....

There is no right or wrong really.

Actually there IS a right and a wrong, but the choice of 'To siphon or not to siphon' seems to be where the confusion is.

Right - whatever gives you pure water for your fish and lots of nutrients to your plants.
Wrong - high levels of ammonia/nitrites in your FT, lots of much in the fish water, bottom full of sediment.
Really wrong - dead fish, sickly plants, smelly system.

Personally I prefer a F&D system - not sure why except the idea of plant roots in constant water seems a bit odd to me. I happily accept those who say there is no difference, but I keep in mind their aeration system has to cope with both FT AND GB's. In a F&D the aeration is provided for the GB and any extra (venturi and air pump) is for the fish. I have a consideration from the many sites I read on about 12 months back that high DO in the FT is an insurance against many problems that kill fish.

But a decently designed system will have multiple passive sources for aeration as well as air pumps. I have yet to be convinced a constant flood system will deliver any incoming aeration to the base of the GB - what little I know of fluidics suggests the incoming water will flow across the top of the water in the bottom half of the GB, taking aeration with it back to the ST or FT.

I'd be happy to view content that shows otherwise, but in dense media (non-moving) the drain will pull along the least line of resistance PLUS aerated water is less dense than solid water, so it will remain at the surface, not somehow sink into the depths. Near as I can work out, the only deep aerated area will be concentrated around the outlet where the holes low on the stand pipe will suck water down from the surface.

And, given the evidence of those here who prefer CF systems, I don't even know if it matters. Maybe plants simply don't need oxygenated water around their roots?

Well yes, the answer to his question IS that there's no right or wrong... I was answering his question, not just making a sweeping reference to all things aquaponics. Of course you have to provide a reasonable environment for both the fish and plants..

So far as the theories behind CF and F&D, I have read many different thoughts and theories, and many seem to make a lot of sense, but often two arguments that seems to make a lot of sense can be completely contradictory to each other..

To date I don't know of anyone that has compared the differences except for the trial we ran of the three systems, and judging by that trial as well as the anecdotal evidence of people running CF systems, the CF systems perform very well.

Aeration? There's only so much oxygen can be dissolved in water, and there's not much point in doubling the amount or methods of oxygenation if it's going to make a 2% difference in the levels of dissolved oxygen. I've seen people with ridiculously large aerators running in tiny little IBC systems because the general consensus bandied around is that "you can never have to much aeration". Yes, you need enough aeration, but you don't need more aeration than is useful. And there can be down sides to having ridiculously large amounts of aeration as you see in some systems. You are far better off being able to see the activity of your fish so that you can watch for unusual behavior rather than more aeration than is physically needed..

Mine runs a 3000lph pump with a 2000L tank on timed F&D.
It holds 75 rainbow trout without issues.

I don't see the start and stop principle being an issue with these pumps, they are magnetic drive.
There are no parts expanding with heat etc

Yep, in nearly eight years I think I've replaced a couple of capacitors in two pumps... and about three timers.... in all my own and client systems.... running timed F&D...

Sorry, but I just don't buy the "timers always fail"... or "turning a pump on/off wears them out faster" arguments...

I've had just as many total pump failures running continuously pumped systems in that time span...usually with small volume pumps...

Hanzelz,

Great thing about what you have bought. You can see what works for you.

Bell on - have siphon. I was fascinated by it to start. Use a coke bottle as the bell and you can watch how the vortex forms.

Bell off - constant flood

Add a timer, timed Flood and drain.

Just make sure your media guard is big enough to get your mits into when you have the bell on.

Thanks guys this is a really useful discussion.

When I get started I am hoping to try different setups on different grow beds and see which I like best. So I will set up one with a bell siphon and one constant flood. Maybe also try the timer method. I will probably also want to try a bell siphon and an external loop siphon.

All of that will teach me a lot and also lead me to where I get the best plant growth. One day....

Regards, Martin.