Pool: Backwash water distribution...Spray?

[Brandon]

Here is the situation... I have a new sand filter( Hayward 310t) and a Pentair Whisperflo 1 hp pump. I had a cartridge filter prior to this( big pain in the rear). But now I need to backwash this occasionally, problem is that the flow rate is about 75 gallons per minute from the 2" backwash hose for about 3-4 minutes total cycle time.This is way to much water for my backyard, as it soaks into the cinderblock fence.( I am in Arizona), and erodes the landscaping while discharging. So, I spoke to the city, I can discharge the water into a common area behind the back wall. I have to be careful about erosion here though as well. there is 10 foot wide strip of decomposed granite between the wall and the greenspace. I need to get the water OVER that. So here was my thought... Hard plumb 2" PVC from the discharge outlet on the valve( buried) to the back wall, run the PVC up the wall to the top edge and put in some sort of spray mechanism. What to use for that.... How about a 2" cap on a 45 degree elbow( so it angles up and away) that has been drilled with 8 - 1/4 holes or 16 - 1/8 holes . ( I cant believe it would be that simple to get the same flow rate) Maybe someone versed in Fluid dynamics can /will clarify... What combination of holes/diameter would I need to allow the same volume of water to escape as an open 2" pipe? Perhaps slots rather than holes?

I also thought about using an agricultural sprinkler head( like for golf courses, but can find one that flows greater than 66.7 GPM.

I have thought about plumbing the discharge to the waste outlet in front of the house, but the distance is prohibitive, about 150 feet.

Any suggestions greatly appreciated.

Thanks Brandon

[Tom]

How about adapting that 2" pipe to a short section of 4" pipe, in which you've drilled the top half full of holes. Kind of like the device you get for the end of your garden hose to water under plants without washing away the soil. Drilling only the top half would cause the water to spray upward and then fall to the ground and I would think you could experiment with the number and size of holes until you felt comfortable with the results. However, for what it's worth...I lived for ten years in Chandler, AZ and backflushed my pool into the grass area in the back yard. After about 5 years of that, the grass turned brown where the pool water was going. It must have somehow changed the chemistry of the soil because I couldn't get grass to grow there, even after I stopped backflushing there. Maybe the chemicals, increased salt in water from pool evaporation, or the diatemaceous earth from the filter....I don't know. Tom.

[Brandon]

That's sounds like an option that may be better if I try to fabricate this myself.

Interesting about your grass, I have been told by every pool person I have talked to... "just use the water to irrigate the lawn or the trees"( this was before I decided it as to much water.) I wonder if they really understand the long term chemical effects. City may not like it if this ended up killing the grass in the greenspace. I should see if I can get the "ok" to discharge there in writing.

Thanks Brandon