how to calculate psi from a power head ?

[newfishliny]

I need to know how many psi come out of a power head so i can add on a check valve , so when I do a top off i can prevent siphoning out of the water container. they make small check valves for tubeing . I know each head is diff but is there a rule,
thanks
new fish

 

[broomer5]

Yes there are rules - many rules.
Each pump manufacturer should provide you with a chart that shows flow vs. head pressure.
You'll need to get your hands on this chart first off.
What powerhead ( pump ) are you considering ?
What is your vertical distance ?
Flow is a function of pressure drop.
Pressure drop is a function of vertical head.
Sounds like you're wanting to fabricate a system where you can pump up water to top off tank - and when the correct level is reached - having a device shut off the powerhead without backflowing~siphoning water back down through the pump ???