Clones with Dark Brown Tips

Hi everyone. I have a few clones that I've transplanted from a bubble cloner into an aerospring a few days ago (maybe 4 days). One of them, oddly the fastest growing one, has developed some very dark brown tips on its upper leaves. About 4-5 leaf tips are infected, or rather, were infect. I snipped the dark tips off. Bad move? I couldn't bear to see them anymore lol. They are not spots. They are only found at the leaf tips and have infected approximately 0.5 cm of the leaf edge. I suspect it's due to over fertilization, but this is the first time I've done this so I'm in the dark. The only plant exhibiting this is growing faster than the rest, and it's got 5 nodes. I wish I could post some pictures, but I don't have a camera atm; very low on funds. Here is my troubleshooting form.

H=aerospring/hydro
T= HydroTon
E-indoor
E-Water source - tap
E-Source water pH - 6.8
HRT-Source water EC (if hydro) - 250 ppm
E-Age of plant - 10 days from cutting
E-Type of fertilizer - GH flora
E-Rate of application - 750 ppm, 4 gallons
E-Lighting source and distance from plant - 4xT12 Daylight CFL, 3x 42W 2700K CFL
E-Air temperature - 73 degrees daytime 67 nighttime
HD-Reservoir temperature - 70 degrees
E-Air % Relative humidity - not sure, but its not humid
E-Lighting schedule - 18/6
E-Type of ventilation your room has - 6" exhaust, passive intake
TR-Did you pre-soak your media in pH corrected solution? - yes

Thanks. Now back to studying...

sorry, that should be 4 nodes and closer to 12-13 days from cutting. Not exactly sure though. roots are about 7 inches long.

You ever treat them with any sort of anti-transpirant? If so, what brand, and how heavily? Do the affected leaves look very glossy, even shiny? Sounds like the verbal description of a wilt-pruf overdose, which is suffocation of the leaves. But pics would help a lot to be sure.

You should be adjusting your fert mix to 5.8 after adding nutes btw.

Hye stink, thanks for dropping by. Sorry, no pics anytime soon. anti-transpirant? Not sure what that is, but I'd say that's not the problem. The only product I use other than the standard 3 part GH formula is AN Jump Start for starting the babies. But I think you might be on to something when you say they might be suffocating, which is why you mentioned the wilt-proof overdose, right? I use those black foam pucks for cloning, and I decided to leave them in because they provide great stability. Did I mention they're extremely constricting and would very likely cause suffocation? And this one plant happens to be the fastest growing in the bunch! so the others who are lagging behind could easily follow suit in the next couple days? Eureka? The ONE thing I didn't mention in the problems form. This newb is impressed :D

I'm gonna go yank the puck out of the sick one, and leave the rest with them in place and see what happens.

right, and PH is always adjusted to about 5.5-6.0

how healthy is the mom?

humidity and moisture combined wth an unheathy mother, have given me black tips on my clippings after about 12 days from clip.

The mom LOOKS healthy, but she has gone through a lot. for a while she was squeezed onto a shelf that only has 2 feet vertical. mind you she was about 2.5 feet tall until i chopped her head off. I wasn't aware that plants in veg could be butchered without harm. so for a while she was kissing up with the cfl's, and i mean tongue to tongue ewww....until i took the axe to her. i don't yet know what the repercussions are from all this, whether or not her babies will be affected adversely, and so on. maybe someone could tell me?