Roots growing upward??

My 3 plants have roots growing out of the rockwool cubes through the top/ side that is not covered by hydroton. Does anyone know what could be causing this?

Lights: 150 watts MH and 150 watts of CFL
Nutes are the bubbleponics nutes. The plants have also been developing brown spots on the tips of the leaves but I think that was due to a high PH which i recently resolved.

I will upload pics as soon as i get my camera in about an hour or two

They are just growing into the moist medium. If it were to dry out fast they would not grow there.

Here are the pics:

Wow! No way of getting them deeper?

Well they are growing down too. Just not as much as normal. I think it may have something to do with teh difference in PH of the water in the res and the water in the rockwool?

I cant seem to get the PH to stay below 6.5 so I am going to get a better test kit and better PH down.

It seems like no matter how much ph down i add, i cant get it below 6.5. What could be causing this ph spike?

i know rockwool cubes are like ph of 9 if you don't soak them for 24hours in ph'd water of 5-6

but they should have adjusted by now. not sure. hopefully someone experienced in hydro will come along.

hmm

anyone else have a theory?