I agree with a lot of the others on this thread. Chicks do not need a de-wormer. Most worms come from free-ranging and eating worms + grasshoppers. Your chicks will not have had that opportunity; and if they are from a hatchery, their parents likely didn't either. They likelihood of gape worms and other types is highly UNLIKELY. There are A LOT of uneducated people raising chickens.
There are a number of reasons that your chicks might not be thriving-- though it sounds like your heat is adequate. I would recommend using a medicated chick feed. While I tend heavily towards organics, the amprolium in medicated feed will address coccidiosis which is the most likely cause of chicks perishing. For electrolytes, a 1/2 tsp. of blackstrap molasses in the chick waterer is far superior to sugar and store bought electrolytes. It is filled with vitamins, and makes absorption of nutrients more efficient in the body. Also, I have had success with dipping the beaks of weak chicks in a tiny bit of yoghurt.
Like so many have expressed, death is a part of the life process and sometimes there are just some weak chicks. I have raised THOUSANDS of chickens and losing one now and then is unfortunate, definitely sad, but to be expected.