Foglie gialle 4 settimana fioritura

I think it's too much fertilizer.. Measuring the EC of the runoff was 1,100 ppm and the leaves are a bit claw-like..

Hi, if the lower leaves turn yellow, it's usually because of too little nitrogen. Nitrogen is a mobile nutrient, so the plant can move it from where it's less important (old leaves) to where it's most important (new leave growth), if it does not have enough. Given that you're currently in mid-bloom i think that you switched from veg-nutrients to bloom-nutrients at the beginning of bloom, however people tend to forget that at the beginning of bloom the plants will still go through a stretching-period where nitrogen is still needed, and the switch to bloom-nutrients should only be done after the stretch is over, when focus is made on the building of the buds.