Anyone know the science behind feminized seeds, how does it work?

looks like nute burn.

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yep defo nute burn mate.

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my job supplements too many bad habits thats why i dont bother buying into a pension scheme........

yes your feeding too much, id stop for a week and then go to 1/4 str. then add 1/4 more till you get to rec. dose. your going to kill em, if you carry on.

Looks like white residue on hydro coral, could be signs of excess salts from high fertiling. crazy-mental sounds like he's got the cure for what ails them and I'd give'm a flush with water only 1st to leach away any excess salts.

check the ppm of your nutrient mix

What is optimal ppm nutrient read for hydro?

And thanx to everyone leaving their suggestions!

Each type of nutrient brand, strain, type of medium, general invioriment, all these things take a part in how much Nuts your plant can take. This is why people build up slowly to figure out how high of ppm their grow can go.

I am one to talk though, I changed strains, brand of Nutrients and even additives, to the grow I am on now. Luckily I caught the problem early. One person even said something about my plants looking like a gave them radioactive nutrients, but who cared, if they have nice buds. lol....

Even if you fix the trouble, you will not see the change in the growth that is there. The change will be in your new growth.

Why are you going for 1 hour watering duration?

I use a different grow medium though. I have 6"x6" rockwool cubes sitting on a 1 1/2" coco matt. I am in flowering cycle right now. The root systems are pretty good sized. So I only flood the tray once a day just deep enough to cover the bottom of the cubes by about 3/4". THEN every 8 hours I flood the tray just deep enough to flood the COCO matt. When I was in Veg. I flooded every 8 hours to about 2 1/2" from the top of the cubes. which was about 7 minutes start to end. and then I slowly lowered the water level I flooded as the roots built lower in the cube. As it is now, I can raise the Coco matt up and see a nice root system laying below.

Good luck on your grow. Does not look even close to how bad mine looked not to long ago.