How much liters/gallons during backwashing?

[rickv]

The pool has bene placed last week. I took pictures of everything, which I'll share soon

Anyway, we need to sort the backwashing of our sand filter. In Perth, Western Australia, you have to ditch the water inground in a soakwell

How much liter/gallon do you flush away during a backwash? That'll help determining how big the soakwell has to be

 

[Brad_C]

I'm in Perth too.

I have a small pool and a small sand filter. My pool is about 2/3rds the size of yours. I have an Onga P21 sand filter that *requires* a minimum backwash flow of 125Lpm (and I get somewhat more than that). I backwash for about 4 minutes and rinse for a good 30 seconds to a minute. Sometimes I repeat the process, so I'd lose a specified minimum of 625L of water. Because the filter is a bit oversized for the pool I don't have to do it often, but it's still quite a lot of water for such a small pool. I'd hate to have to try and get rid of that water in the yard.

I'd also be wary of pumping that much salt into the ground over a prolonged period, but that is based on nothing other than gut feel and absolutely no science or background.
I have a *long* set of pipes I put together to get my backwash into the stormwater on the road (like nearly 40M). Big pipes required to keep the pressure drop low.

 

[rickv]

Thanks Brad. I just spoke to the pool building company and they said it needs at least four 600x600 soakwells, sjeez...I can't put that into the ground without redoing my entire garden.
Besides that like you said, you are pumping quite a bit of chlorine/salt water into the ground...hmm