The big keys in water retention would be the electrolytes, sodium, potassium, and chloride. Sulfur can also affect cell permeability, but for any candida sufferer, I would strongly suggested using molybdenum for a week or two before using sulfur to help improve sulfur metabolism. You may want to add about 1/4 tsp of Sea Salt to each liter of water. If you have no benefit from that, try adding potassium chloride, and see if that helps. Sodium and potassium are always in competition. If they get out of balance so does water regulation.
Plenty of water is still good, especially during detox, but self-regulation should occur, you should not have to become a fish to stay hyrdated. When all else fails, look to the minerals.