Simple head question

[RonL2]

Looking at pump curves charts, it would seem that when a pump starts up (40 psi) it is roughly 47 less head than when it hits its cutoff at 60 psi. Would that mean the pump would actually deliver more water when it starts and slowly diminish until it cuts off ? And the same principle for the static water point ( if it drops while the pump is running, increasing the head) so you use worst case of 60 psi and the low static water point (I guess it wouldnt be static then.. would it ? ) and maybe since they're an opposite force, they cancel each other out ? I just find this very interesting. Any thoughts on this ?

 

[Reach4]

Looking at pump curves charts, it would seem that when a pump starts up (40 psi) it is roughly 47 less head than when it hits its cutoff at 60 psi. Would that mean the pump would actually deliver more water when it starts and slowly diminish until it cuts off ? And the same principle for the static water point ( if it drops while the pump is running, increasing the head) so you use worst case of 60 psi and the low static water point (I guess it wouldnt be static then.. would it ? )

40 is 33.3% less than 60, but that does not matter. I am OK with the next stuff.

and maybe since they're an opposite force, they cancel each other out ? I just find this very interesting. Any thoughts on this ?

Head the pump sees as pressure goes up goes up, and head the pump sees as as water level in the well goes down goes up. So not opposite.

In deciding if you have enough to gpm to backwash a filter, I think you would care about the gpm at 40 or even lower (typically 30 at the input of the backwashing filter). I mention gpm for a backwashing filter because a backwashing iron filter is typically the highest gpm user in a house. Irrigation is not in the house, and for irrigation for a house, it is best to match the irrigation setup to the pump rather than the other way around.

If the gpm from the pump reduces as you approach 60 cutoff, that is expected and probably desirable.

 

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[RonL2]

Yes, I had that reversed, increase pressure, head goes up, lowering water, increases head also. So as pump runs, gpm will start high and then go down.
And yes I have a back washing filter (not for iron, just a large carbon plus mineral filter) I had actually forgotten about it, since its automatic once a week in the middle of the night. But it has it's own valve mechanism, and I dont believe it just opens wide open, just enough to stir up the carbon to create new pathways.
Thanks to experts like you this forum is very educational and i for one appreciate all the help given here !!!

 

[Reach4]

And yes I have a back washing filter (not for iron, just a large carbon plus mineral filter)

Carbon and what mineral, and how are the two medias separated? -- or are they mixed? Is that carbon to remove chlorine or peroxide that you inject earlier?

Typically a 10x54 inch carbon tank will backwash at about 5 gpm, or a little more. Some media takes a lot more flow. Softener that size backwashes with 2.4 gpm usually.

 

[RonL2]

It is a kdf/gac filter.
The kdf is encapsulated in a perforated sleeve surrounded by the gac.

Here is the page for it.
https://www.pure-earth.com/backwashing-KDF-GAC-whole-house-water-filter.htm

 

[RonL2]

I use it on my well even though its suppose to be for municipal

 

[Reach4]

It is a kdf/gac filter.
The kdf is encapsulated in a perforated sleeve surrounded by the gac.

Are you injecting chlorine bleach solution before that?

 

[RonL2]

No sir, no injections, just the filter.
Original purpose was to remove a smell from the water. It had a garlic smell. Not the unusual sulfur.
Smell it in the shower, in the ice from refrigerator. Plus once in a while a pond type smell. The filter has eliminated all of that. That's why I used the kgf along with gac. You never know for sure what's in your well. It can change every day. And since mine is only at roughly 40 feet, I always thought it couldnt hurt.