I had mutant new growth and posted a thread but got nothing, so took my pics too grow shop and I was told it was probably due to spraying them. I used neeem oil, but all sprays will coat the leaf and can suffocate them leading to deformed stunted growth, try spraying them with ph'd water to rinse any residue off. Also, with my PK alot of the new growth looked funny as it first sprouted, i kept trying to correct it thinking it was a deficiancy only to find they would look great in 3-5 days so have come to realise thats how mine grow. Also with promix hp check your ph runoff. I've found with both sunny#4 and promix hp that I have to keep ph going in a little high, 6.5-6.8 so that the runoff stays above 6. If ph going in is low 6 then I end up with runoff of 5.6-5.9 a little low for soil. Hope that helps.