I used the sensi calmag the entire first grow and i think its N is 4. Never had nitrogen issues with it. Do you think the flush would be able to flush what was absorbed by the plant?
Ok, there are 2 different flushes. One is to eliminate salts and / or start correcting pH problems and nute lockout.
To do this flush you water right up till you get a tiny bit of run off then you let it sit for a while to break up / disolve what you want to eliminate. Then you run 3 or 4 times the size of your container worth of water through to flush out your medium. (3 gallon pot, run 9-12 gallons through) some people use a light nute solution to do this flush with, some don't.
The second kind of flush is a pre harvest flush.
We used to do it just to get rid of as much as we could of the stored nutes because with the slow dry and cure method I was taught you get a much tastier and smoother smoke. Some people can taste the difference, some can't.
Now I also do it to try and get rid of contaminates that are unhealthy. Soil is the worst but you can also get heavy metals in peat and other mediums, and you can get mercury in fish byproduct based nutes, or crap leaching from Chinese pots into your medium, etc...
Unless you pay for a lab analysis proving otherwise it's best anymore to just assume you at least have some level of contaminates.
That flush as the name implies is done right prior to harvest and you have to be able to read your plants to determine how long to flush. 6 days, 8, 10, 14...... depends on size, fullness, bud maturity, medium, heavy drinker, etc.
I was taught that the perfect flush ends up being just like in nature. You get rid of excess and the plant then eats itself from the bottom up to finish out and you chop when done.
Time it wrong one way and you hurt bud production (worst case) time it wrong the other way and bud production is fine but you need to chop before completely flushed.
Obviously the latter is better. It's also the best way to learn.
Definitely a helpful thread. Thanks 
