New Grower Question / Hydro Problems

I am having problems with yellowing spotting on my the leaves, this follows with a the leaves drying up and dying. The plants are a couple of months old and now in the flowering stage.
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I am using an ebb and flow active hydro set with 400 watt lightin a 6x6 room. A co2 system also runs 24 hrs a day. The room temp is kept between 72-78 degrees at all times, the hummidity between 40-60%. PH is regularly checked and maintained between 6.6 and 7.0.
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In an attempt to fix the problem I flushed the plant with plain water for 2 days and cut down on the nutrients(Fox Farm, Bcuzz and Diamond Nectar) by only adding 13 Gallons worth of nutrients in a 15 Gallon reservoir.
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1 and 1/2 weeks later the yellow spots are still spreading and the leaves are still dying.
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I probably won't harvest anything worth wild on this batch, but I want to know what I am doing wrong before I begin a new set.
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Any advice would be greatly appreciated.

 

Yellowing of leaves is normal during flowering . Remember to remove dead leafs to stop possible mould problems. Do buds look OK?

 

One plant turned into a male so I took it out immediately the other 2 plants are not showing any signs of male or females. They have branches that break off from the main stem that look like they are going to be flowers, but there are no hairs or pistols.

 

Be patient.

 

What else? Is it possible they can still be females?

 

i agree with buffoonman, be patient and manicure the plants to get the dead leaves off. during flowering some leaves will start to die off, mostly the bottom ones and the ones in the very center of the plant close tothe stem. this is normal. you just want to remove them to avoid mold issues. its a good thing you took the male out to avoid hermes. keep up the good work!!!

 

I wait until the leaves fall off then remove them.

Males do not cause "hermes".

 

So do I