There are a few things I would like to mention.
@420masterofdon
These 700mA far-red puks should have ~14-15μMol/s/m²(calculated with 40% efficiency). Thats ~40μMol/s in a 0,36m² tent(2x 2'). One need ~2000-4000μMol(not per s/m², just μMol) to put the girls into sleep mode so you need to run it only for 50-100 seconds to give them the amount of far-red they need. It works with the dose princip just like UV..
If you use far-red you'll ALWAYS get more stretch! Thats normal behavior! It depends on how much they get.
I usually use 2000μMol EoD treatment at the beginning(12/12h) and increase slowly to 4000-5000μMol until finish. When the stretch is done I also use it over the day for other beneficial effects(increased leaf temps, compensation between PS-I and PS-II, emerson effect). This way the additional stretch is pretty small and the plants finish only ~2-4' taller in the end.
White light already contains red and deepred wavelength so you should profit from emerson effect even without additional red/deepred diodes. For this reason many user have switched to CRI90+ because it has much more red and deep-red and twice as much far-red compared to CRI80. Even though CRI80 is more electrically efficient the better spectrum compensates for this and depending on the strain you are using you can get even better yields in less time if you use CRI90.
But remember, the emerson effect gets weaker with increased brightness. With 1500μMol/s/m² there is no improvement anymore. With only 400-500μMol/s/m² you'll see huge improvements.
This is how mother nature has created a way how plants get along well with less light.
But when you add more red/deepred wavelength you make your whole light more efficient and depending on the brightness level it also increase the emerson effect.
I've added a few science papers about red and far-red and a link to an interview with doc hernandez. I know, its a lot to read and the interview starts with UVB light but it's still worth watching it completely.