Bastard white streaks on my laundry

[Vitamints]

Help!

I have a washer-dryer, and always do an extra rinse and spin for allergy reasons. Colour tablets, hard water, no fabric softener. Recently I've been seeing white streaks occasionally and wondered if the machine was overloaded but this green hoody went through on a very small wash. What's going on?

I have a box of white and a box of colour tablets to use up so was hoping the washing soda might work without having to shell out for a new box of detergent so soon But you make a good point about it dissolving and I guess it does allow more flexibility with dosing.

Hard water is the devil's own spit.