Depends on how you purchase it. Let’s look at a cost comparison of GH Flora using Lucas Formula + Calimagic at full strength compared to the GG formula using four parts. And we’ll game this out using my flower tent as the baseline to keep it simple, and assume I use all the space in the 40 gallon reservoir.
So, for the entirety of the grow, let’s assume it goes 10 weeks. This typically means something like five reservoir changes for me, so 200 gallons of water in total, let’s say (in reality this is probably close to accurate because I usually run 30-35 gallons in the tote and top it off every couple of days in mid- to late flower).
40 gallons of water would require the following in Lucas Formula (totals):
Flora Micro - 8ml/gal x 40ga = 320ml
Flora Bloom = 16ml/gal x 40ga = 640ml
Calimagic = 5ml/gal x 40 = 200ml
Multiple that then by 5 times for all the system changes and we get the following:
Micro: 320x5 = 1.6L
Bloom: 640x5 = 3.2L
Calimagic: 200x5 = 1L
A one gallon bottle is 3.79L (according to the label), so at the end of this one flower period we’d have the following leftover:
Micro: 2.19L
Bloom: 0.59L
Calimagic: 2.79L
Extrapolating the math you can figure the following ratios used up per flower period:
Micro: 42% of the bottle
Bloom: 84% of the bottle
Calimagic: 26% of the bottle
So rough calculations let’s say we can get one grow out of the gallon of Bloom, two out of the gallon of Micro, and four out of the gallon of Calimagic.
So let’s base our cost on four grows.
Costs per gallon of each:
Micro: $31.99
Bloom: $29.99
Calimagic: $40.50
For four grows (flower period only), then, our total would be two gallons of Micro, four gallons of Bloom, and one gallon of Calimagic.
That totals up to $224.44 to get us through 4 flower periods, or $56.11 per grow for nutrients.
Now let’s do the GG formula for 40 gallons of water.
Jacks Part A: 2g per gallon x 40 = 80g
Jacks Part B: 2.7g per gallon x 40 = 108g
Epsom Salts: 2g per gallon x 40 = 80g
MKP: 1.2g per gallon x 40 = 48g
Multiplied by five system changes:
Jacks Part A: 400g
Jacks Part B: 540g
Epsom Salts: 400g
MKP: 240g
Typical purchase size for dry nutes is 1kg, so these prices are for 1kg bags.
Jacks Part A: $23.99
Jacks Part B: $22.99
Epsom Salts: $10 for four pounds (1.8kg)
MKP: $13 for 1 pound (.45kg)
So with the original purchase above, the Jacks Part B becomes our limiter (540g per grow) - and we can get four grows out of one bag (540g * 4 = 2.16kg). MKP is also a limiter (240 out of 450g used for each grow means we need roughly one bag for every two grows).
Going with four grows, we’d have the following left over:
Jacks Part A - 200g
Jacks Part B - 40g
Epsom Salts - 200g
MKP = 0g
Looking at four grows, then we need to purchase 1 on of each of the first three parts and two bags of MKP. This puts our total, for four grows, at a whopping $82.98. Or $20.75
The cost comparison then is:
Lucas Formula + Calimagic = $56.11 per grow
GreenGene Jacks Formula = $20.75 per grow
So switching up is costing me less than half what Lucas was costing me. If this all works out and I like this nutrient line, then I will be buying 25# buckets of these nutes at a reduced cost per gram.