When you pee try to hit the dry part of the toilet bowl. Afterwards, look at the bowl surface and look for fine crystals.
If you can see them then you need more fresh water. I used to get that when I had heartburn problems and took a boatload of TUMS. The high levels of calcium can not stay in solution and precipitate out as a calcium salt.
Dark urine means dehydration yet you're taking in a lot of electrolytes... so you might be seeing (peeing?
) something like I had.