Nutrient burn or deficiency?

Cannot tell if this is a nutrient burn or if it’s a deficiency.
Started experimenting with using half Britta and half inline hose filtered water in super soil. My pH here is insane. 8.2 out of the tap. I didn’t want to use pH down anymore so I mixed the two types of filtered water and the pH comes out to 6.5.
ppm out the tap is 560 today
They change water sources every so often
My pen calibrated
That’s what the water is like.
These were clones that I had put into purple cow super soil. I’ve used it a bunch of times.
Works great. Some of the plants have burn leaves, some of them are starting to have discoloration, and one of them is totally fine. The largest of the clones is not showing any negative affects.
Wondering if the Britta filter is taking something out or if the soil is just hot
I have a few other plants, and none of them are like this, only the youngest of these clones.
Last picture is the same strain, same soil, no issues.
Maybe it just hasn’t happened yet?
So yeah, is the soil hot? or is the Britta filter taking something out?

Probably a combination. Your water is probably high in calcium which locks out magnesium and potassium. And that soil was probably hot when you planted them and fried a little of the older leaves. What is the final ppm of the water you're using after you mix them?

Whatever comes out of the tap. It’s usually around 500
I only grow this way because it’s easy and really don’t want to go through Ro water and adding back what ever I am missing.
never had a nutrient burn from this soil so I am a little surprised.
I might go coco again
It’s turning into a hassle with the soil

Seems like it’s not damaging new leaves
Only getting more dramatic on the already affected leaves. Looks like a potassium deficiency from the water being off or a nutrient burn from the kelp that I foliar fed.