Is Run-off EC measurement affected by EC of base water?

Hi,

I saw on cocoforcannabis that, when doing high frequency watering, you want to aim for the run-off EC to be around +300 compared to input EC, in an ideal situation.

Question is, if your starting water isn't at 0 EC, how does that effect the ideal run-off EC? Does it go up by 100 if your input starts off at +100? or down by 100? etc?

Lets say my water is starts at 200 EC, and then I end up watering at a level of 1600 after adding nutrients. Run-off should ideally be 1900 in that case? Or lower?

Thank you

Pretty sure its simply what goes in and what comes out. So no it shouldnt matter other than that its part of what the runoff ec is.

Funny you say I asked myself that question yesterday but answered it since I been doing this a while. I could be wrong but just my two cents.

Of course whats more important is whats in that starting water. I was told I have things in mine that can effect a grow. I been lucky lately though.

I asked myself because I was testing runoff and asked myself, does it matter if I rinse the tray with water that has .5 ec? Will using a wet tissue wet with said water effect the reading?

I used it to clog the tray to take a reading. I think thats similar to what youre asking.

What can however effect readings that someone pointed out is if you didnt clean the tray its in.

You're overthinking it.

If the EC is substantially higher then you need to flush and lower EC

You don't even need to check run off unless you're having a serious issue

With substantial run off every time, you should never have a problem or a need to check it.