The method you use should be determined by what type of results and samples you have. I have a Spectrex Laser Particle counter, a Sedigraph 5100, and all the stuff to do the pipette technique. I bought the Spectrex laser particle counter for measuring size distributions in very dilute suspensions. The unit also counts particles, so you can tell if your solution is too concentrated. It is very difficult to get water clean enough to use for your dilutions.
Tap water has thousands of particles in it.
The best method I've found is to let a great quantity of distilled water sit for 6 months and then decant from the top. The method you use should be determined by what type of results and samples you have. I have a Spectrex Laser Particle counter, a Sedigraph 5100, and all the stuff to do the pipette technique. I bought the Spectrex laser particle counter for measuring size distributions in very dilute suspensions. The unit also counts particles, so you can tell if your solution is too concentrated.