I actually grow my AR mini under medium- medium high light, with minimal CO2 (or none) with the similar light and it doesnt stretch like that.
Im not sure what you are dosing, but you did increase the saturation in your photo to try and make it look more red and cover the significant algae on the bottom leaves. So it seems to me the photo could be misleading.
I guess you could try more light and popper ferts.
Giving back creates a virtuous cycle that makes everyone more successful (as long as they cycle!)