Want to turn it up a notch.

So I am about to complete my third grow. I have had not bad success (about 6 oz per grow) but would like to turn it up a notch. I have my suspicion of where I went wrong but would like some constructive criticism.
At the end of each grow in about the last 4 weeks of flower I tend to get nutrient burn in the tips of the bud leaves and through out the plant. I did notice early this grow and did not add any nutes since. I follow the feed schedule for the flora trio but this continues to happen..
I am growing in a 4 ft x 30 inch space. It is well ventilated and I have a king 1000w led light.
I water approximately every three days, only every second feed with nutrients. Usually every watering I use cal mag. Approximately 2.5 ml per gallon.
Once larger they get about a half gallon of water per plant in 5 gallon pots.
So I am thinking one of downfalls is that I do not water until there is run off. I do read a lot and I am guessing that nutrients build in the soil and at later stages it burns the plants.
I have 1 plant about 2 weeks behind. I stopped adding nutrients and it seams to be doing better.
Pic 1 shows the worst plant. It is at 63 days of flower. The one in the second pic shows the one 2 weeks behind in the front left.
This is black jack from bag seed.
My buds always seem to have good potential but just don't really fatten up.
Thanks

Youdidwhat said:

So I am thinking one of downfalls is that I do not water until there is run off. I do read a lot and I am guessing that nutrients build in the soil and at later stages it burns the plants.

Click to expand...

Indeed. I use a drain to waste system so all my runoff goes to my floor drains. Bucket in a bucket type setup so there is no open standing water for gnats to grow in.

What temps are you running? You need warmer temps under LED due to the lack of IR.

A better light wouldn't hurt.

Thanks
My temp is about 82 with lights on and 70 off..
Humidity is about 60 but I have very good air flow and ventilation
Last 2 grows I lowered rh to 45 at the end.

I think you have been underwatering.

With not enough runoff I suspect your salts are buiding up causing toxicity of soil, which can effect nutrient uptake.

You should be running way more water through a 5gal pot. My 2gal pots takes over a gal to water them....?

Water til you get a good amount of water coming out bottom of pot and you'll have less issues later in flower cycle.

Lime