Brown spots please help me.

ihave rcently put my seedligs into my dwc system. they are growing strong and have nice color but im noticing some small brown spots coming up on the leafs in the middle. everynew se of leaves looks good but shortyly after the new set comes the prevous set starts do develope tiny bron spots all over the leaves. any suggestions on this problem would be great. i could take some pics but my camera isnt good nough to pick up the tiny spots.

More often than a deficiency when you start seeing anything brown that is starting with the older leaves and then progressing usually means it is due to too high a concentration of nutes, which is throwing off your pH...this is my assumption without seeing pics, but that is most likely to be the culprit...unless you are using RO water and not supplementing any calcium... I have never every given my plants calcium in 4 years...ooohhh except once...Lol... and because I added calcium to a plant that didn't need it I really got to see what a Cal-Mag deficiency looked like because adding it messed everything up..most nutes add calcium and magnesium, besides the fact that they are in most water in most places, including but not limited to well, city, and bottled water...so again unless you use distilled or Reverse Osmosis water, than it is super super unlikely you have a calcium deficiency....too much nitrogen will lock out calcium, and cause brown spots..which is what a calcium deficiency does look like, but it is more likely to have too much N locking out Ca then it is too have not enough Ca in a plant....plants really don't need much calcium to survive and thrive...