Ok, this is not for a home use or a pond. This is a tank filled with 60 gallons of water and a 2inch tube going upfrom it to another similar tank, im wondering how much air pressure i need to exert to push the water straight up
Each foot of elevation is equal to .433 PSI of water pressure. You would have to overcome this pressure difference to move water upwards. I'll leave the compressibility of air calculations up to the number crunchers, but this should give you an idea.
Good luck.
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If the speed of light hasn't changed, why is it getting dark later?
Also be aware that the air will pressurize the lower tank, so make sure the tank can withstand the pressure. It may even need to be tested and certified as a pressure vessel.