The loss of color can be attributed to lack of direct sunlight. Color in the foliage is from a concentration of sugars formed during photosynthesis. These intensify the red pigmentation. In a great deal of shade, these sugars are not produced to the same degree and the pigmentation is weak.

Some red leaf dissectums hold their color better in low light conditions but the best coloring will be in more sun. In fact, red leaf maples are generally extremely sun tolerant and can be grown in full sun in many areas of the country.

This color 'change' has nothing to do with watering or soil chemistry or anything other than sunlight and the plant's genetics. Some just hold their color better in low light conditions than others. If you want your tree to remain red, you need to locate it where it will receive more direct sunlight.

+1...and stop watering every day or you'll wind up with root rot.

I would guess it is sun exposure. I have two large Crimson Queens next to my front door and the branches that get sun exposure are nice and red. The underlying and low branches are green.