Agreed...Light also plays a role...what type of lighting are you using? My hottest point is 1600ppm and then down from there.Denser buds come from genetics, not a bottle.
you should always aim for 65 or you're going to have problems, in dwc at least3000 PPM is sure yo kill your plants within a couple days if you dont change the water out.
Seedlings- 200-250 ppm
Veg-300-600
Pre Flower-600-800
Flower- 1000-1600
Keep you Ph between 5.8-6.2 is you can. You also want colder res water (around 65-6 while flowering. During veg you should aim for 70-80.