How big of a reservoir would you use?

For a 49 site aero, 4x4 nft/aero setup, Al B Fuct style? I'm hoping to get away w/ a 35 gallon res, but I'd need it to last 16 days before a res change. Of course I'd top it off as necessary, and the plants would be lollipopped.So what do you guys think I can get away with? I really don't wanna go up to 40 gallons, but if I have to I will.

I run 50gal res for 10-12 plants in a nft/aero set up and after week 4-5 in flower they can suck it dry in 5-6 days.

Rule of thumb here is 25 gallons per 1000 watts.

A~~~

I have never seen or heard of any comparison of res capacity to light wattage. Who's thumb?

All depends on how long you veg for an how big they get.

16 days could be to long for before need a top up

18 gallon res. Is all you need for a 4x4 setup with 49 little plants gauranteed

Okay, so based on the responses in this thread, I'm gonna start off w/ 30 and up it if need be. Thanks fellas.