Is there any truth behind coco runoff?

For example I'm wondering if runoff is lower ec than input do you need to up your feed strength?
And dame the other way if runoff is higher should you drop your feed ec or does this jnly work with hydro systems?

Roughly speaking if you put in 1.2 ec and it comes out 2.2 ec then you've likely got salt build up.

But coco is not inert , it releases k slowly and depending on the coco (pre buffered out the bag or dehydrated block) other elements.
So variation in ec of run off is to be expected.

The time to be checking it is when you see a problem.
Most likely if you've hand watered every other day in veg and you hit a problem 3 weeks into flower , youl probably find you've accumulated salts in the coco and caused a lock out and when measuring run of ec it will be very high.
So you flush .