Maximum water flow from an
airlift pump 
Limitations of calculation (outwith
these parameters the calculations will become less accurate): 

Pipe diameter 1.5  8cm 

Pipe length 60  300 cm 

Q = ((0.758 x (%s)^{1.5}
x h_{t}^{0.33}) + 0.01196) x d^{2.2} 
Where ; 
Q 
= 
Water flow rate, litres per minute 
h_{t} 
= 
Total length of pipe (cm) 
d 
= 
diameter of pipe (cm) 
%s 
= 
Percent of pipe under water (measured from
point of diffuser to discharge) 
Air requirements for optimal
water flow are typically 89% of the water volume. Above 10%, normal
bubble flow ceases and the efficiency of the airlift drops rapidly 