Bell Siphon and Oxygenation

[Julian Chawarski]

Greetings,

I am new to aquaponics but have been researching for months and am ready to start an expirmental setup in my home before I take it to a large scale. Its seems that the bell siphon system with a media bed seems the simplest and most cost effective way to start a system. I know that the bell siphon draws a good amount of oxygen down into the roots of the plants growing, but does it also oxygenate the water well enough for fish without haveing to add supplemental oxygen? I know everyone says to use tilapia which tolerate wide ranges of conditions, and I might well use them, but I am more interested in developing a system for other species that may require higher DO conditions.

Any info would be greatly appreciated!

Losing sleep over the excitement of starting a system!

Julek

[Jonathan Kadish NYC AA Chair]

If you had 5 fish in 100 gallons you could probably get away with it but at higher stocking levels having your aeration depend on pumping water is setting your self up for a catastrophic result if your pump fails. Having both a water pump and a air pump gives you another level of life support redundancy. Ideally you would want another level beyond that if your power fails having a battery or generator that automatically kicks in.

[Julian Chawarski]

Thanks Jonathan, that makes sense. Redundancy was one of the last bits I needed in the design process. Appreciate it

[TCLynx]

I was able to get away with only water pumping and the water falling back into the fish tank for the cooler months of the year on my 300 gallon system with small bluegill in it but as soon as the weather warmed up the fish quit being interested in food  and I added the air pump back into the system and the fish started eating again.  Warm water doesn't hold much oxygen and even tilapia won't eat well when the dissolved oxygen falls kinda low for them so your redundancy doesn't have to be an air pump/air stone but you probably will want some means of extra aeration beyond just what the siphon emptying the grow bed does for you, at least during warm/hot weather.

And as noted, an air pump on a battery backup switchover is a good thing to have in case of power out or water pump failure.  Sure there will be more things that could go wrong but hopefully not all of them will go wrong at the same instant and perhaps give you a chance to fix what does go wrong before the fish die on you.

[Keith Rowan]

you can find a 4 outlet air pump that only uses 5 to 8 watts...

higher oxygen levels are good for the fish and the plants and the bacteria