EC levels variation when transitioning from top feed to roots in water?

After a few grows under my belt in my current RDWC I’ve come to learn that practically every single online “guide” to EC levels wants me to way over feed my plants. I do only veg for about 4 weeks, and run a chiller, a Venturi, waterfall returns, lots of DO, basically everything that helps the plant uptake more efficiently prompting a need for lower EC levels and from experience it seems like as soon as I get around 1.0 EC even in the heat of flowering that my ppm will creep up day by day indicating that I should lower feed levels.

EC levels around 1.0 in the heat of flower extrapolated out for an entire grow would make me think that something like 0.3 or 0.4 might be good for early veg coming out of the seedling phase but that just feels awfully low. Additionally I’m thinking that until the roots are in the water and the plant is feeding off of my top feed halos that all of the factors prompting such a low EC level in flower would just be irrelevant.

My entire system holds ~30 gallons so it’s difficult to see movement in that much volume when plants are so small and eating so little. A drop in the res by ~.25cm or around .5gals a day doesn’t change monitored EC levels regardless of what I’m feeding them. I bet I could set the EC at 4.0 and a week later it would only be at 4.1 with dead plants. So I’m hoping to fish for some guidelines here or generalizations.

1) GENERALLY do plants want/need higher EC levels when relying on the top feed portions of a bubbleponics system, and then as their roots get down into the water and they have easier access to a constant supply of high DO water and nutes their desired EC levels go down?
If so, any rules of thumb for EC levels for top feed potion of their early life, keeping in mind that 30gals isn’t easy to see movement in with such small plants.

2) should I view the top feed portion of life and the “roots in water” portion of life as two totally separate grows with separate desired EC levels, or are they comparable enough that extrapolating out from my observed 1.0 during flower isn’t a horrible idea (it’s difficult to have high confidence in observed EC movement before flowering because of my short veg time and large volume in the res, a seedling just isn’t going to move 30 gallons no matter how hot the mix is). Different styles of growing/feeding do have different guidelines for EC
 
1. no
2. no

my EC was almost always below 1 in rdwc. i usually started at about .3ec
I’ve only made a few posts here but you’re always there with a response, i appreciate it.

last post I had was about the need for cal mag when using tap water with a native ppm of ~120 (500 scale, ~0.2 - 0.3 EC) and now that I’m skipping it entirely it free’d up some ppm for NPK.
I’m assuming that’s the better use of my EC limit
 

rkymtnman

Well-Known Member
i think too many people use cal/mg when they "probably" only need mg. especially in tap or well water.
 
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