Height of LED lighting - Trying to make plants stretch

[ToughCall]

Howdy,

I have a Spider Farmer SP4000, great led, love it so far.
Directions for height state Veg cycle 18" to 24".

Is that the height from the soil surface to the light?
Or is that from the top of your plants to the led light?

I'm asking as I'd like to make the plants grow taller prior to switching to flower.
They're entering week 6 in Veg and I've done super cropping, trimming, as well as LST the past 3 1/2 weeks.
The plants seem to be fine and recovered from stress. There is no bleaching or burning of the leaves.
The SP4000 is about 16" from the top of the tallest plant, and 18/6. I'm feeding 700PPM, & Ph is 5.6 to 6.5 random averages.

So, If I were to raise the light to 24" from the canopy top, would they naturally grow/stretch towards the lights more?

May 16th marks their 6th week in Veg phase. They're height has been manipulated to be lower with the LST. But are all at least 12" at the height after LST.

The OG Kush are typical Indica, bushy and short. The Kryptonite are tall & leggy. Two of the three Kryptonite are 8 days younger and notably smaller but at 12"

Long story, but hopefully that all helps.
Goal is to understand if I should base everything on height or the age befor flipping. Should I raise the SP4000 to stretch or would it?

Thanks,

[sourshoes]

Use the height of the plant.

sent from space

[ToughCall]

Much appreciated, thank you.