is my res big enough? also need to know where i can get something to auto top my res

I have the CAP ebb n flow system, I will be vegging for 2 weeks and using the Lucas formula the whole way through. what is the maximum # plants I should put on a 55 gal res?

Also I have a stealth 100 reverse osmosis filter, anyone know where I could find a automatic device that will top of my res when it gets low? Thanks

You can pick up a float valve from any hardware store for about $5, or you can buy one from a grow store for $25 - no kidding. I'm not familiar with the workings of your E&F system, but if your res. empties temporarily, only to refill once your cycle is done (like my aero system does), you'll not be able to use a float valve. Your res would overfill during your first feed cycle.

this will require a 2nd control res to top it with a timer and float valve, IMO it's more work and trouble than help. if you just get a big res you could go for a week or so without topping

5gal of water per plant is good.