Sodium Aglinate? Water Softener?

Those ingredients are options, depending on the results you are trying to achieve and your water hardness. Hard water can cause duller colors. Sodium Alginate thickens the chemical water, and will slow the wicking of the dyes. This is useful if you don't want a lot of bleeding between colors. Urea is a humectant and helps in the batching process if you are doing direct application dyeing and you live in a low humidity climate. I don't use the water softener, even though my water is pretty hard, and I am satisfied with the results, color-wise. I detest sodium alginate personally, and prefer Dharma's Superclear if I want thickened dyes, but many use the s.a. with great success. Most of my dyeing is low water immersion these days, not direct application, so I don't use urea, since batching is different for LWI. I think it's a matter of experimenting and finding what works for you... I have found that dyeing is a pretty loose, forgiving process, with guidelines rather than hard and fast rules. The most important thing is that you use your mordant (soda ash solution for cotton & rayon, vinegar for silks) to achieve bonding between the dyes and the fibers... the rest is optional.
Judy