the way i see it is you pay for what you get, to me an extra 30 bucks isnt much when im only using 12gallons of saltwater a week so a pale does me quite a while i can see price being a problem if you need to make a couple tankloads in a hurry. i use to use instant ocean but after visiting some other peoples tanks the proof is in the puddin, ill only use two kinds now h2ocean or reefers best.im sure others will ring in the exact differences as some have been testing to see whats better but i bet the majority of the better tanks are using h2ocean
cheers