I've been buying pre mixed salt from either LFS (red sea pro I believe) or Petco (Imagitarium), and was doing 20% water changes monthly.
About a month ago, I bought a 10kg bucket of Aquaforest PROBIOTIC for ~$50 It is the same as their "Reef Salt", but with some extras (amino acids, probiotic bacteria). This makes about 65 gallons @ 33ppt according to the box. This is enough for 4 rounds of W/C. I started doing weekly 10% w/c - 3 gallons in my nano, 12 gallons in my bigger tank.
This coming weekend will be my 4th water change using this batch of Aquaforest Probiotic. I definitely noticed a difference. My tank was in a sad state. In the last few weeks, corals are re-bounding, colors are popping, and the algae on my glass has gone down significantly. Also the salt mixes very very easily.
To be honest, I don't know if the change is coming from the salt, or better husbandry. The probiotic salt is a bit pricey. I did just order a 25kg box of their regular reef salt for $60. This will make 175 gallons. Now that I have been able to keep the nutrient levels down, I think making the switch to the regular salt make sense. I am also dosing 1 drop/25 gallons of probio S, and -NP Pro daily.
There has been a lot of hype behind the Aquaforest brand, but I have noticed a positive change since switching. Another pro is that it is very very very easy to mix. It takes about 15 minutes to mix.