First Hydroponic Grow, NL99. Advice needed.

What's up world. This is my first grow. I'm at an important point and I need some advice.

Joey Weed Northern Lights x Cinderella 99 from seed
Ebb & Flow system w/ 7 gallon reservoir
15-minute flood cycles every 6 hours of light
FloraNova and FloraMicro nutrients currently kept at around ~750ppm and 5.3-6.3 pH
400W white spectrum Metal Halide, currently 24/0
Hydroton medium

Today would be Day 17 since germination and the plants are in full-on veg. I started with 15 seeds (maximum the hydroponics table could hold), but pulled four from the table at Day 13 after observing no germination, or very stunted initial growth.

I'm pleased to say that the rest are growing explosively, but some appear stronger than others. My flood table is relatively small (about 2' x 2') and I need to pull more weaklings/males to make more growing space for the stronglings/females. But at this point there are no preflowers so I don't know for certain the sex of the plants. My only clue is that I noticed from the start that these seeds produced two types of plants, (1) the faster growing, slender ones, and (2) the denser, squatter plants. The squatter plants with the broader leaves seem to be much happier on the whole than the taller, slender variety. As you should see in the picture, three of the five plants of the slender type have leaves that are fucked up in some way (edges curling up, tips bending down -- and this has persisted since the first true leaves formed on those plants).

I don't think the environmental conditions at this stage are the primary cause, as the majority of the plants appear to be very happy and are growing fast. Just bad genetics on those plants?

For those familiar with the sexual dimorphism of cannabis or the strain NL99 specifically, do you think the taller plants (which also generally have more fucked up leaves) are the males? Do you think it'd be wise to pull the plants that appear to be the least healthy so that I can have more space on the table to veg the healthy ones?

First they look very good for a first grow. Way to go.

At this point all you can go on is the health of the plants. You can weed out the weak ones. However you can't tell male from female untill flowers start. They are just showing phenotypes of parents. Seems like all I see no matter what strain they do this.

Best thing to do is start to flower when you have 4 true sets of leaves. When they proof and show sex then pick out the best plants. The ones that show you the best health and go back to veg and clone away. These will be your mothers. I know it takes more time but in the long run you will more than ketch up. And all will be female without dought.

Hope this helps, I'm shure we will get more opinions. Go with what you feel is right.