Measuring EC/ppm of runoff

So I've never watered to runoff before. Trying to switch to Mega Crop nutrients and they suggest at least watering to runoff twice a month. I checked the runoff of the first two plants. Super high, not even sure if it's possible. Second plant measured in at something crazy like 4500 ppm or like 9.0 EC.

Is that even possible without killing the plants. They seem to be very healthy. This is the third watering. Before I was watering plain water with organic amendments.

Canna Coco Professional with perlite.

Yes, it's possible as I had run off that measured at 8000! But I had lockout with salt build up and was in flower, it's my first grow, but I do know that you should always water till you have runoff water at least 15/20% or you can get a build up of nutes, but I'm using coco, not soil.

Cococakebaked said:

Yes, it's possible as I had run off that measured at 8000! But I had lockout with salt build up and was in flower, it's my first grow, but I do know that you should always water till you have runoff water at least 15/20% or you can get a build up of nutes, but I'm using coco, not soil.

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Hmm. I'm also in coco. Checked in with Greenleaf Nutrients for directions on whether it's required to water to runoff. They suggested watering to run off once every two weeks to prevent any build up.

Definitely going to have to keep even closer watch going forwards...