ph 6.3 in, ph 5 out... wtf?

I'm using promix HP. I've only watered it twice... once with ph 6.3 for planting, then with ph 6.3, ppm 600 for the first feeding. I'm using botanicare. The runoff tests 4 days later came out at ph 5 and from 1000-1600 ppm! This is just nuts! I don't understand.

The HP is brand new, so the lime should still be in there... I didn't add any more dolomite, which could have been a mistake...

I've never seen such a drop. I'm flushing now, and I've only fed once. This is not cool. My leaf fringes are curled up, and there are some twisted leaves. Oh, and some of the lower fan leaves have rust spots.


So it turned out that Promix HP (high porosity) contains nutrients from the factory (as stinkyattic pointed out... thx).
http://www.hort.purdue.edu/hort/faci...s/proMixHP.pdf
So the plan is to not feed until the second week at the earliest, and then only with a mild nutrient solution. I'm thinking around 300-400ppm... I followed botanicare's instructions for seedlings, and this was way too much.

more to come...