Backyard Aquaponics
A place to discuss aquaponics

How do I know if the air stone/curtain is suited to my air pump? I have a 30L/min air pump but dont know how much air stone I need

What type of pump is it. And what is the pressure. My air blower does 300L\min but it does not do a great pressure. So it will run 60ish stones but only at a small depth.

Its best to check the pump specification and try to keep the backpressure within reasonable limits otherwise the pump wont last as long as it should. Long runs of small bore pipework can add a lot of resistance

+1 for getting one with pressure.
My 30L/min electromagnetic does SFA below about 40cm.

Is it possible to put to much air into the tank.

If so what effect would this have on the fish.

Not when using normal air. It can happen when using pure oxygen.

Too much (plain air) would probably be when the fish are getting bubbled right out of the water by the amount of air.

How to know what air stone to get. If getting good ones, there should be info on the packaging or in the catalog about how much air (liters per minute or whatever) is recommended for the stone at a particular pressure. I understand that a depth of 28 inches of water requires a pressure of 1 pound per square inch to push air down that deep and the rule of thumb I learned for the stones is that they usually require another 1 psi to push the air through them. I needed to figure the amount of air in cubic feet per minute my pump could push at 2 psi. I'm not sure what the numbers are for other unit measurements and I'm sure everything gets more complex if you are using long runs of tubing smaller than appropriate for the amount of air you need to push.

My air pump is supposed to push about 3.5 cfm of air at 2 psi. The air stones have a suggested cfm and say if you push more air through them than the suggested amount, the bubbles simply get bigger. In the big tank I have a stone with a suggested cfm of 1 and the smaller tank has a stone with a suggested cfm of .75.

I don't know if any of this is of help to ya. I've noticed that many little aquarium air pumps don't even tell any info about how much air they really push, they just say they are appropriate for a certain size aquarium or bowl.

Good quality airpumps aren`t cheap, even the replacement diaphragms are pricey so it pays to look after them. You can buy pressure relief valves for pond air pumps, they usually operate when the pressure exceeds 200mbar.

It may be worthwhile making up a simple tube manometer situated well below the pump height and tee`d into the outlet to indicate what the pump is doing pressure wise.
If the reading rises overnight to some silly level you`ll know an airstone is blocked or a pipe is kinked/trapped etc and if the reading drops by a large amount then you could have a leak in the pipe, an airstone fell to pieces or the pump diaphragm is on it way out

For long pipe runs its better to use a ring manifold made from large diameter rigid pipe and spur off that to individual airstones.

I have heard of people using this stuff as an alternative to airstones.

http://www.bunnings.com.au/products_pro ... _1001.aspx

http://www.bunnings.com.au/products_pro ... _1002.aspx

Thats what I use

Probably not as efficient as an air stone as it does not break the bubbles down to a really small size. Trout dont seem to mind.

don't use airstones or air pumps
they are not efficient (my opinion)
use the power of your pump and growbeds for aeration
more efficient as you have that anyway
(sorry, guys, just couldn't hold myself for more than 3 days)

frank

Im with Frank on this one
Ive got a pump in each tank specifically to circulate the water and on both of those there is a small "venturi" like fitting ( which comes with the pump in the box ) , they push out a huge amount of bubbles but the pump needs to be fairly close to the surface to get maximum bubble-making flow

Im eventually going to get around to putting needle-wheel impellers in both of them to smash the water into tiny bubbles as it sucks it in

excellent solution, Boris
but I would be careful with the needle wheel impellers as too small bubbles might be dangerous for the fish

frank

What about when your not pumping water then Frank?

I dont run the main pumps to the growbeds during the day.

Practical Experience Here.
1 x 65 watt water pump running through a 0 head pressure inverted (spraying upwards for more aeration) spraybar = sad trout.
1 x 20 watt air pump running through weeper hose = happy trout.

I used to think that running an extra pump for aeration worked the best, and was efficient - I now know that for my circumstance it is not.

Nothing scientific here, just my observations.

empirical evidence FTW!