Stem Problem need help!

This is my first time grow. I am using an aero garden i have several plants about 3weeks old and one of them is beginning to have a build up of a white crusty substance on its stem. Any Advice would be appreciated. Thanks

from the looks of it, it looks like the stem is shedding, whickh means its getting thicker, but the pic is fuzzy so im not 100% shure

If it isn't the stems skin cracking from growing larger, then it is most likely salts build-up.

Try flushing the system with PH neutral water, Reverse Osmosis or Distilled would be best due to the lower PPM levels.

Yeah its a cell phone pic... there was much more at first but i kinda knocked some of the white stuff off with my finger, but there are now 2 light brown spots on the stem as well and a few of the larger leafs on the bottom of the plant are a little brown at the tips. I was told it may be white powder mildew but am not sure..ill try to post a clearer pic.

do u have a fan on your plant so the air is moving? that might be your problem

Should the fan be blowing directly on the plants? or as just in the room to circulate the air?

Directly on plants,they should wave in breeze.