@WeedHound - Well I just got back from the store not too long ago and and I do now have a decent PPM meter and some CalMag. I would like to let you know that I talked to the guys at my grow store and now realize what the fuss was about with the 40gal resv. I have a 2x4 flood table that is ~6 deep. The 40gal has enouph water to flood my table all the way. They also said that adjusting PH and nutes is easier in a larger resv. So it looks like I'll just stick with the 40gal. Now the other thing I was thinking about is that, I have only 27 one gallon jugs for filling, so I won't be able to let all of the water sit out over night. I usually put 35gal. in the resv. so thats a difference of 8gal. that would be able to sit over night. The brita filter said it pulled chlorine out of the water so I was wondering if I should fill those last 8 with brita filtered or just regular tap? And lastly....about the PPM thing...I guess what I'm trying to say is, how do I know how much overall PPM I'm supposed to be sitting at, at any given time (for example, I know I'm supposed to be at 5.6-5.8 PH, is there some number like that for PPM)? And, if thats the case how do you mesure your nutes based off of PPM instead of tsp/ml/gal or whatever? I'm going to measure my PPM in my resv., tap, and brita filter and let you know what I come up with.