I germinated a variety of seeds and I now have the starts inside, under two full small spectrum LED lights. I'm using a couple different mediums. Some are in rock wool. Some are in a store-bought starting medium. Some a combination of both. I'm watering once a week by pouring ~1 inch of water into the tray for an hour (then dumping out). I'm adding an organic kelp fertilizer to the water at the recommended dilution.
I notice almost all my plants have crispy yellowing tips and it doesn't seem isolated to specific types of plants or mediums I'm using. Any ideas what's going on?
More requested details
I'm using two of these full-spectrum LED lights: https://www.lowes.com/pd/GE-1-in-1-Light-White-30-Watt-Single-LED-Grow-Light/1001001640
They're hanging approximately 3 inches above the plants. I turn them off for about 8 hours every night, but occasionally I forget and they get 24-hours of light.
Details about the water: I'm using tap water + a splash of organic kelp fertilizer. Where I live, there's no chlorine in the water.