Hi, just arrived from Istanbul, and finished checking my setup, all is well.
This is for Frank from Carolina, we had a quick conversation on skype about a week ago, and he's trying to set up 14 half barrel with loop siphon. Roughtly something like this should be the setup.
Roughly, I would recommend about 20 ~ 30 watt pump (1000 lt/hr) per siphon, so you require about 40 ~ 60 watt pump (2000lt/hr) for 2 loop siphon.
The best arrangement would be one pump per siphon, this is easiest to requlate and provide fail safe arrangement, one big (reliable) pump can do too. I've made a mistake of using a big pump, its works just that water management/division is a bit more difficult.
In Frank case, the pump is more then required, the excess water can just be dump back into tank via the third ball valve, or you could send it to a filter.
On using timer, its all depend on how fast the water will fill up those half barrel, I would recommend switching off the pump at night. During day time operation you just have to see how it goes.
The setup should not have problem with or without a timer, as long as you don't forget to incorporate a small leak/drip hole at each siphon.
BTW Frank, as per your note on skype, "15 min ON and 45 min OFF" cycle with a Timer, with this setting you don't need a siphon system for flood and drain, this timing is for flood and slow drain using stand pipe in each half barrel and a small leak hole at bottom of each stand pipe to slowly drain water out.
This arrangement is more simple to do, and in one of my Aquaponics How to Start, I did briefly include this method.