I came up this system after learning what others are doing. As far as I know, no one is doing exactly what I am working at. So I would like to report shortly what I do. For those who prefer to watching the video, here is the YouTube video I made:
I already reported this system on my website here
https://dripgrowtower.com/1/new-design-dripgrow-towers but for those who can grasp the concept quickly, I summarize below...
Basically I used a T connector to make a low power airlift pump which can lift water to vertical grow towers up to 7 feet high - could be higher. Here is a picture showing the simplicity of the T airlift pump:
I then placed the airlift pump and associated tubing inside a gutter drain downspout. Holes are drilled on the downspout to hold grow net cups. Then I inserted this downspout into a plastic container which was really a Christmas gift wrap container I got from Canadian Tire right after the Boxing Day. The finished setup is this (the black tubing is the only part sticking out which acts as the air inlet):
I like the vertical grow towers because it is perfect to use the DripGrow method for slow drip feeding and it has eliminated all the plumbing problems associated with water-filled system powered by water pumps.
Using airlift pumps can also supply both the water and air at the same time (a must for aquaponics especially), which works even if the grow system is almost entirely enclosed to prevent water evaporation.
Here is another shot showing a second tower placed inside a shallower container with snap-on cover, side by side along with the first tower:
Hope my design inspires others!