Weird plant, need help

Hi, I'm new to all this so pardon me if I'm doing it wrong. I planted my seeds that I ordered. Out of 9 seeds only 3 sprouted. 2 of them are doing great but one of them, well it's getting brown splotches on some of the leaves. You know how when it grows two leaves come out then new growth starts to come up, four leaves grew at the same time, then the new growth is growing out the side and it's only one leaf. I have them all in the same dwc unit. I'm using cfl's. I have 2 of the long aquarium air stones. I haven't added any nutes yet because I understand I'm supposed to let the cotelydons yellow and fall off which hasn't happened yet. It's been growing weird from the start. Please help. Is it just a bad seed? Should I not go back to this vendor? Can't figure out how to post a pic. Any help with that would be great as well thanks in advance

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Maybe root problems?

Yeah maybe. The roots just got down to the water though

check the roots and check for light leaks

and your going to want like 100ppm to 300ppm of micro feed or a weak seedling feed in that water

I concur, that's big enough for some nutrients. As said, 300 ppm or so will work but ya, get some nutes in there. Sorry you got stuck with hydro corn. Roots love growing into the nooks and crannies of it and it's a bitch to clean and get any dead root out to reuse. I'd suggest shooting for some of the perfectly spherical stuff next time, i used the corn once and will never use it again, switched to use Canna Aqua pebbles and love it.

Hydro corn? Never heard that. Yeah just got the cheapest thing. Didn't know there was a difference

Changed res, added nutes. pH is good. Hopefully I'll be able to tell something by morning