Backyard Aquaponics
A place to discuss aquaponics

Hi,


I want to bild my own Aquaponic and I was wondering why you need a bell syphon and not a normal one?

Welcome to the forum. A bell syphon is not needed. A simple overflow pipe with constant flood or timed flood and drain works just as well

But why do people use a bell syphon what are the benefits of it?

If you install a bell siphon you can remove the bell at any time and you have a constant flood system, so you can switch between the two systems as it suits.

When the water is siphoning out of your growbed it is drawing oxygen to the root zone.

It probably isn't necessary if you have plenty of dissolved oxygen in your water.

The original idea and function of the bell syphon, as Arbe has mentioned is to drain the grow bed so that it can be replenished with a new volume of water and to introduce oxygen throughout the media and roots of the plants.

But also as Mantis and MrD has commented, there are other methods to get similar outcomes such as flood and drain via timer or a highly oxygenated constantly flooded system. All of which are aimed at turning over the water volume and providing air.

BYAP did a fantastic trial between 3 different methods that I think everyone should read through at some time. It really puts things into perspective and as we all found out.... there is no real right or wrong.

viewtopic.php?f=51&t=8621&hilit=trial%2A

Thanks a lot !! I have my answer

There is one more issue not mentioned - a siphon system (look up afnan also) allows you to run a Flood and Drain system WIHTOUT turning the pump on and off. Most electrical and mechanical equipment suffers wear in the start phase, and can get stressors in the warming and cooling stages. There is a reason a taxi will get a million kms of use where your car, exactly the same model, will probably die at 150,000kms - the taxi very rarely gets to cool down.

Basic physics (or engineering if you wish) says a pump will last a LOT longer if it is never turned off than if you are doing a regular on-off cycle - and most recommendations are along the lines of 15mins on and 45 mins off, or even more frequent.

with a bell or afnan siphon the pump runs constantly - the F&D is achieved by the physics of the siphon, not by a switch.

There is a 4 year warranty with the $110 BYAP 3000LPH pump.
It costs around $120 per year to run that pump 24 hours or $30 to run 15 min on, 45 min off.

If it only lasts its 4 year life, by running f&d you spend $120 in power compared to $480.

So even if your theory is correct, as long as the pump lasts 18 months on f&d it pays itself off

You are neglecting the other costs of failure. That pumps is the life of your system - potential costs far exceed mere replacement of the pump.

True if you're comparing the same pump...

...but the pump in a timed flood and drain system running 15 min on, 45 min off will need to be 4x the size of a pump in the same aquaponic system running 24/7 through a siphon... if you want both methods to turn over the same fish tank water volume every hour, which is what's recommended.

The pump in the timed F&D system has 15 mins in which to get the entire fish tank volume through the GB, whereas the pump running constantly in the siphoned F&D system has the whole hour to turn over the same volume of water.

+1 - Beat me to it Mr Damage.

And you need a reliable timer!

I ran first two years with a bell siphon, changed it over when I didn't have the water level right in the growbed, and haven't put it back on. I have noticed no difference in plant growth since changing to CF 6 months ago.

I did find that before roots were established in the GB, that muck cycles between bed and tank with the bell, but all goes to bottom of bed if CF. With established plants, little gunk gets back down and water remains clear. Is that important. I figure if the fish are in clear water they will taste better than if swimming in mud. Not sure if that will actually be true, but happy to give it a go.

We've had one of our pumps cycling 15 on, 15 off, 15 on, etc 24 hours a day for over 2 years now without skipping a beat... We have not had a timer malfunction here at the shop in my living memory. Yes there used to be some dodgy brands early on, now we have found a reliable one and get NO problems at all, ever... I keep hearing this around the place, "Oh but times are dodgy, they break down all the time." Spend $10 instead of $3 and you have no problems..

As to having a larger pump? Hell yeah, the bugger the pump the more likely it is to pump your solids, better to pump more for 15 minutes, and suck up those solids, rather than trickle 24/7.


But then I'm arguing for the sake of it, personally I prefer a constant flood most of the time, and have a dislike for flippant siphons..

EB,

Do you still work on the rule that you need to pump at least, ie as a bare minimum, one volume of water per hour.