Backyard Aquaponics
A place to discuss aquaponics

Yes that's right Zman

DD - did you have the air stones in before the big pipes? I had intended to do the same thing but my stones just sit on the bottom and seem to be cycling the tank enough to keep the gunk from building up on the bottom. If i used this method would the water turn over be better do you think - would the pipe add more pull to the bubbler? I can see that i could mount the stone higher and therefore would be pumping more due to less pressure from the water...?

Hi BB, yes I had the air stones just sitting on the bottom before. I think ducting the air stones does pull from the bottom better, if nothing else because the holes in the bottom of the pipe mean the flow has to come exclusively from the bottom. It's just making it into an air lift, which should move the water more directed-ly than just an air stone. The difference in height is not that great between the middle and bottom the pipe, maybe two inches, so I moved the air stones all the way to the bottom of the pipe. The stones I'm using are cylinders and the air stream is not really complete until about three inches from the bottom anyway. I had the 4" pipe for awhile and I can't remember what I was going to use it for, so hey why not?

That it is...

The difference though is that normally you are making an airlift to actually pump water over the edge. But in this use it's just circulating, may or may not be obvious for people to try as I have not considered making air lifts for my system before because they have almost no oomph.

But for this purpose of circulating water in a bio-filter while also adding aeration, perfect use of an air lift.

What would happen if you put the air line into the 3/4 pip filled with gravel but then had a few holes to direct the air? Would that work in the same manner?

Nope... the media would prevet the "airlift" effect... which isn't that strong...

I've seen applications like this... to supply nft channels placed across the tank...

How about just a pipe with holes and air lines going in and something to hold down the pipe? Wouldnt it have the same affect?

yeah i do believe this would work, all that is required is air bubles traveling from near the bottom of the fish tank through a straght pipe to the surface, you dont really need to use air stons or defusers, this sort of thing is used by some marron farmers in dams to mix the water and eliminate thermoclines and keep water temp reasonably even throughout the water body.

Cool. I always intended to do this but when I got my bubbler it was rated to 2meteres and at 1 it is bubbling but i never got around to my original ait lift action. I think it could work better. If i can lift my bubblers to 50cm or so - my bubbling would increase greatly and get maximum turning and effect.

- i have always wondered on this. is a bubbler in this scenario going to create a better result than a open air tube? Also, should i split my stones to make 3 pipes (like yours dd) or put them all in 1 pip for max effect? I have an IBC so could do maybe 1 in each corner where the pump is not (its in the 4th corner), or 1 big 100mm pipe with all 3 stones.

I'm not having any D.O. issues, or sediment buildup isues, but if it costs $5 to get the best cycling avaiable....

Going on from that, couldnt we just stick an air line on the bottom on the tank, pointing it upwards have the same effect?

Hey Z i think you missed the post from DD a few above. Yes is the answer but the tube imprves the effect by pulling from the bottom layer of water more strongly resulting in more mixing effect...

Google eductor or on Wikipedia, the fast moving bubbles get a larger mass of slower moving water going. You can get the same effect by streaming a narrow stream of fast water from a pump into a large diameter tube. This gets a much larger mass of water going, but more slowly than the stream from the pump. A small fast moving stream transfers energy to make a large slower moving stream. This is good if you're not trying to pump to a head height but just want to circulate a large mass of water.

I plan to suspend net pots on the surface for the Winter, so needed some way to circulate it well. I'm thinking of switching the four line air pump to FT duty and putting the two line pump on biofilter duty. I think I have enough pipe left to make one or two more lifts. I want two row of pots going down the long edges of the pond.

Here's an eductor in a reef tank, could be an option instead of a propeller pump or air lift:
http://home.comcast.net/~reefboy1/Eductor.jpg