Backyard Aquaponics
A place to discuss aquaponics

Ive been relying on the water splashing from the grow bed back into the fish tank to provide the oxygen in my system but now it seems ill need to get an air pump. The dissolved oxygen level was around 5 ppm but now as my tilapia grow it has gone down to 3ppm. They've all begun hanging out where the water falls back into their tank rather than swimming around the entire area. I have a 650 gallon, 3 ft deep fish tank with a 170 gallon grow bed and 20, 1 1/2 lb. tilapia. The pump runs 24/7 and turns the water over hourly. With that sized system, approximately how many liters per minute would I be looking at?
I was looking at this -
http://www.theaquaponicstore.com/Active ... phf011.htm
Maybe its too small though or maybe not very good quality?
I understand the air pumps are usually loud but are they REALLY loud? As in would neighbors be able to hear it?
Thanks

What size water pump do you have, if its a little bigger then needed you should put a t-piece in it after the pump then a tap and send it back to the fish tank and reduce the end nozzle size or put a large hole spray nozzle on the end to create extra air into the system... Do you have your fish coming to the top for air if so you really need an air pump but if you dont you shouldnt need extra air....

just looking at some of these air pumps and they seem expensive in power (as in wattage/LPM) if you are ever looking at a backup power supply... good price i think in dollars.... just the wattage used for the litres of air per min is the only thing i would look at...

The pump is pumping about 600 gallons per hour and the fish tank is about 600 too so I don't think I safety divert any of the water from the grow bed. The water flows in on one end of the tank and the fish have started hanging out right there near the surface. They are not gulping at the surface (or at least I have not seem them gulping) but they do all stay near the top. They appear to be feeding the same as always but they are not swimming all around the tank.

Hi Delilah, I was in the same situation as you and spent ages looking through the forum for an answer. The advice above regarding returning water as a means to add oxygen is sound but so also is an air pump. I could not decide between the 2 so I use both.

I got a Pond One O2 plus 4000 (http://www.pondone.co.uk/airpumps.php). it is fantastic and turned my 4000l tank into a spa. It is important to make sure that the stones you use match the output of the pump so it does not "wear" out the diaphragms.

These pumps are quiet. In fact they are so quiet that when I plugged it in i went and got the instruction booklet to see where the on/off switch was so I could turn it on.
They come with a 3 year warranty which is a real bonus.
the only down side is that it may be too big for your system but then you could just bleed air off to ensure it is working to capacity.

Here in Oz they retail for around $100 which to my mind is real cheap.
Best of luck with your system

Marc

I have one of these air pumps too. Very quiet.

There was a discussion on air pumps a while ago where I learnt that while they have a 3 yr warranty it doesn't cover the diaphragm.

One question that I have regards durability in an outdoor setting. The ones that I have used that failed seemed to rust up on the inside, or get intermittant electrical shorts. I assume they don't like the gulf coast humidity here. Do typical aquarium air pumps work outdoors well, longterm ?

I can't speak for your typical aquarium air pump and their outdoor use. All mine are indoors and work well. The Pond One O2 plus is designed for outside use and is enclosed in a weatherproof unit. So far mine has worked well without a hitch.

Now It's time for me to 'fess up. I put my air pump on the ground when I was installing it up near the roof. It was intended for only a couple of minutes so water returning along the air lines would not be an issue. Well the couple of minutes turned into 45 and when I returned water had made it all the way back to the unit and was inside. I pulled it apart and drained the water from the inside and then started it up again. It worked and has not missed a beat since.

Hi All
this air compressor/pump i used for +- 2 Years outside
standing under bucket with a brick on top
all aluminuim ....still looks like the day i took out of box
and most important ...still working 100%
untill i need the pump for the system i use the pump to make brew vermitea
very big for what i need but something i had

No problems with mine yet. Very quite as mentioned.
Runs cooler than the Haliea I had as well.

The information you are looking for is here...

viewtopic.php?f=12&t=6646

From that thread:
Aeration
Though flood and drain grow beds provide all the aeration that the plants and bacteria needs, it is good to have supplemental aeration for the fish tanks even if it is not strictly needed to keep the dissolved oxygen up for the fish, the extra circulation provided by the aeration can help keep fish tanks cleaner. Also having a supplemental air pump can make it easy to hook it up for battery backup in case of power failure.
-1 cfm (cubic foot per minute) at 2 psi (pounds per square inch) for 400 gallons of fish tank.-
?aprox 18 liters per minute at 13 kPa for 1000 liters of fish tank

If you need help with the math, let me know. I'm feeling too lazy to do it right now... (although I do like math...)

these are my aqua400's they have been like this (and are still like this)yes iam a little slack as they have been there for over 22months sometimes under the plastic sometime not(when i have to go get the plastic sheeting from next door from the wind hehehe) has been in the rain and sun many a time and still going strong.... Its quieter the the feeder fish eating...
In the middle of the picture on the blue crate under the reel of tubing...