Hwo to do the conditional snat

If you have multiple VIPs, you only apply the SNAT config to the VIPs that need it.

If you are using a single VIP for all traffic, then something like this will work in an irule

when CLIENT_ACCEPTED { 
    if {!([IP::addr [IP::client_addr] equals "10.0.0.0 mask 255.0.0.0"]) } {
        snatpool snatpool1
    }
}

The above irule will use a snat pool called snatpool1 for all clients that don't have a 10.0.0.0/8 address.

Regards,