I don't use Master Blend combo, I only use General Hydroponics so I'm afraid I really can't help you with a comparison between the two mostly complete fertilizers. I am a GH fan. I have used GH for 30 years now, and I am still loving it. Even after the worst happened, and Monsanto bought the company. It's still a great product. They do not include calcium or magnesium in any great amount in the formula. Making you buy that product separately from them, or from somebody else. Still it's a great fertilizing program whether used indoors, or Outdoors. It's also a wonderful product for fig tree cultivation, and also propagation. It helps promote those nice thick main stem whip trunks, and thicker Scaffolding branches so helpful in growing a great fig tree. Also having it have built-in pH balancers is very helpful, but you'll still want to dial it in with their ph up and down products to get it exactly where you want it.