Advanced Nutrients HammerHead Advanced Nutrients HammerHead is a PK formula that’s a bit different than the PK 13/14 that the majority of the market makes. Advanced Nutrients claim that the PK 13/14 is not the right ratio and that science dictates that PK 4/10 is much better for flowering plants, with PK 4/10 you are much less likely to create nutrient burn by over fertilisation. Advanced Nutrients HammerHead also contains many ingredients to aid plants in peak blooming periods What we know is, it works very well and is a good flowering stimulator. Advanced Nutrients HammerHead is hailed on many forums and by many top international growers as the optimal PK booster. Advanced Nutrients HammerHead is compatible with Advanced Nutrients pH technology meaning growing just became easier when used with the rest of the pH perfect range there is no need to check or adjust pH levels as they are automatically adjusted and maintained at the perfect levels. Advanced Nutrients HammerHead Feed rate – 2ml/Litre in late Bloom.