New Sprout, growing very slow

So i am on day 10 of my plant, and at first when it sprouted it came up quick but not to tall and its standing up fine. Recently it seems to be growing a much slower rate, the seed leaves are yellow n falling off i think. I also found some gnats and i am currently dealing with them, i'm just wondering because the first set of leaves look nice and the next set look as if they are coming out of top but have not made only a very small amount of progress next to none, and thoughts/ideas? Also using mg:/ all i can use, its a pretty welfare set up haha

if you have knats then thats the problem, the baby knats feast on the roots and the adults eat dead plant matter they find on the ground or around the bottom of the plant, if you can get a jar of lady bugs they will make short work of the knats, the larve live in the soil and thrive in wet conditions so its tough to get rid of them

yea, stupid miracle grow soil seems to have a bad rep. I put about a half inch layer of sand and i've only seen 1 or 2 gnats the past 2 days. Killed my first indoor sprout but i have another going now, thanks