I meant also taking the cost of trace elements ( for instance I use to use Red Sea A, B, C, and D. At almost $20 each)
And at Bulk Reef Supply I can get 3.5 lbs of all for reef for $75 that makes more than 2.6 gallons =10 liters, I use 1 liter in 2 months at 17 ml every 24 hrs, that gives me 20...