Questions about PH levels before and after watering (runoff)

Hey GC,

Please point me to the right direction on this one. My filtered brita water seems to have a PH of 7.2 so I PH down to about 6.5 on the water and then water the plant.

Then I measure the runoff of this brand new Roots Organic Soil I just watered with and it comes out like 4.

Naturally it tells me to just water the brita water at 7.2 PH and see if it balances it out, but it's still reading around 4's (PH).

So I have 2 questions:

1) The PH reading on the runoff water is the most important value, right? Meaning it doesn't matter what PH water I put in, because it only matters what comes out right?

2) What do I do then? Ph UP to like 8 and water it and see what it comes out at?

I wanted to clarify this first before doing anything actually.
Stats: 400w HPS, Roots Organic, Fox farm trio line, Only PH meter is the dye drip tester (The kit that has that + PHup/down)

 

/bump

 

/bump - hasn't been answered yet.

 

Of course man.

I measure the PH of the runoff water on my roots organic soil and the PH comes out to be like 4. So naturally it tells me there is something in there that is really low in PH and I'm not sure if my plants get nutrients from it.

So you guys don't measure the PH off the runoff water?

 

This is why I got into measuring PH of my water and what not. My stems are purple too but healthy. But a lot of the times they show a calcium and on rare cares magnesium deficiency. So I tried Cal Mag. It didn't help...

So at this point, it really narrows it down by saying the nutes are gettings locked out due to PH issues because certain nutes are only available on certain range of PH's.

Then I decided to get new soil from Fox Farm Ocean Forest to Roots Organic. On the FFoF, the Brita filtered water I adjust the PH so that it's at 6.5ish or slightly lower and then water it (all nutes are available in that range). Then I measure the runoff and it's about the same when it comes out. I also adjust the PH on my brita water that I put Big Bloom and Grow Big/Tiger Bloom into and again, the runoff water is about the same.

But when I changed it to Roots, Everything comes out like 2-3 ph lower. I'm thinking Roots PH'ed it down on purpose so that it doesn't result in other people's plants getting nute burned?

Either way, I'm thinking the PH I get from the runoff is more important than the PH of the water you put in (or equally important); because it's the soil that takes the benefit either way and it shouldn't come out all off on the PH after you mix water+soil together.

Can someone correct me on this if I'm wrong? This is what I'm trying to find out. Is the PH level on the runoff water equally as important? Should the water you put in be adjusted to reflect the ph outcome of the runoff water? Meaning should I adjust my PH of the water that I put in so that it balances out @ the runoff.

Below is a Nutrient Availability Chart.

 

It's ok, but the reason you get purple stems is because your PH is off.