Thanks small_ranchu. I thought I post some pics of my testing of the 1" airlift that I took today. There has been a lot of research for airlifts but they are mainly for aquaculture type of research and use large diameter pipes. Submergence, bubble size, air injection etc etc will affect water volume moved and height lifted. For most of our applications in aquariums and tubs, we do not need to lift the water above the water surface and our pipes are usually smaller than 2 inch in diamter. I have been trying various types of air injection (air hose, various airstone/diffusers, pressure chamber, etc). What I have found is that the original czech airlifter is the best compromise among water volume moved, lift height, and bubble noise. The same czech airlifter design is the basis for the excellent jetlifter (mainly used in the Hamburg matten filters and sponge filters) and the Yamabuki airlifter for koi ponds that is popular in Europe. So here are some pics of 1 inch diameter PVC pipe using an old German Wisa 110 air pump (oh, boy, I wish air pumps are still made that way) that delivers about 3.5 liters per minute of air. The airlift has a 19 inch submergence (for the 1 inch above water surface lifted pic) and 15 inch submergence (for the 5 inch above water surface lifted photo). For the 1 inch lift, It can fill a one gallon milk jug in about 16 seconds. Remember, for our use, we do not need to lift the water out of the surface and there is no absolute need for the 90 degree elbow so the air lifts will move even more water. However, measuring and testing that is a little more complicated by using vented plastic bag tied to the water output. In my 3-gallon bucket filter, I use 1.5" PVC pipe and it moves even more water but it is difficult to measure because with that type of pipe and volume of air injection, it can only lift water above the surface a little but it does move a lot of water when the pipe terminates at or just under surface. You can see the water level near the exit pipe shoots above the static tank water level and that is showing how much water is being moved. The pic with more flow is for 1" lift. The center of the PVC pipe is 1" above water. If I lower the pipe so the top of the pipe is just at water level, the amount of water increases dramatically. Generally, smaller diameter pipe has less water volume moved but higher lift and large diameter pipe has more water volume moved but lower lift, when everything else remains the same. In many youtube videos, there seems to be much water velocity/pressure. However, keep in mind that they typically use 1/2" or 3/4" pipes. (and a 1" pipe has 4 times the area of a 1/2" pipe and almost twice the area of a 3/4" pipe). I have tried these as well and they have higher lift and higher water velocity but less volume. That is why I am mainly using 1" diameter pipe. It seems to be the sweat spot for the typical aquarium use (air pump volume and water exits below water level). Plus 1" pipe is the perfect diameter to DIY sponge filter using many of the large replacement sponges (hydro or XY type). The pic with less flow is for 5" lift. The center of the PVC pipe is 5" above water. Also the submergence decreases from 19" to 15" (more submergence is better). This is not the best or most efficient way to use airlift so it is just for reference/comparison. At 5" lift, there is still quite bit of water moved/lifted with 1" diameter pipe. The other pic shows my DIY Czech airlifter.