Is 18 Gallons too much?

Ok, so we originally went with the stelthhydro 6gal res bubbleponics system. After researching about how a 6 gallon res. obviously isnt going to be enough to grow properly, we have modded a sterilite 18 gallon tub. We have 3.75 inch net pots up top and all of the pumps tubing etc from the original bubbleponics system. We're using the Flora Series. My concern is the cost of the nutrients that will going into the 18 gallon res. In fact we're not even sure how much nutrients should be added on such a large scale (we're use to the aerogarden lol ). Can anyone that is familiar with the flora series help? We're looking for how much nutrients to add per gallon in what increments and how often. Thanks to all in advance...

bummmp....

I ran into the same size problem. I Built a 6 site system and found the 18 gal to be a little more than I needed. I put the same lid on a 10 gal storage tote, and it worked just fine. As far as nutes, I have used the flora series in hydro and found that 1/3 to 1/2 strength works just fine. Hope this helps.

how many plants. i belive the bigger the res the more stable the temp. mine is 15gal. on 6 plants and it seems to work fine

I find that 5L per plant is generally sufficient. Much more and the plants won't have a chance to make a dent in the amount of nutes in the tank before you dump, clean & mix a fresh tank every 2 weeks. Much less and the plants will use the water faster than the nutes, causing nute strength to bump up, requiring frequent topping up with plain water.