Leafs getting light green color

I would say that looks like ph spotting due to too lower ph or too much ph swing. If you google cannabis ph spotting you will find a few images that look identical to your first pic.

I though it was a light stress,thanks m8 for reply

Those seem to be signs of slight Phosphorous (P) deficiency and a Potassium (K) deficiency - foliage starts to yellow from tip to center of the leaf with light blotching, petiole and stems become weaker and purple in color. It's quite easy to get that kind of deficiency during flowering since cannabis needs a lot more Phosphorous and Potassium during that stage to produce flowers. Try increasing your PK fertilizer (usually labeled as "Bloom" or "Flowering" fertilizers) by about 20-30% and if the leaves turn back green (except for the blotching which cannot be repaired) then slowly increase that dosage as the plant matures. Don't forget to water until there's at least 20-30% runoff (water coming from the bottom of the plant while irrigating), and to check both irrigation solution and runoff for pH level (optimal range for cannabis is 5.5-6.5). Hope this helps! Good luck and happy growing :)