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Old August 24, 2017   #187
zipcode
Tomatovillian™
 
Join Date: Jun 2010
Location: Romania/Germany , z 4-6
Posts: 1,582
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I made a mistake 2 pages ago when calculating the NPK of 'the formula' (masterblend+calcium nitrate etc).
Noticed this when I saw accidentally someone selling pre-mixed stuff on ebay, and they call it (they and everyone else on amazon and wherever) 19-18-38 premix etc. Which is a big fat lie (not obvious it seems since no one in the amazon comments even mentioned this).
Those numbers are supposed to represent percentage of weight. But if you mix half masterblend and half whateverer in weight (be it sugar or calcium nitrate), you get half the values (yeah, obvious).
So the formula (rounded up a bit) is 7.5-7.5-15 +10Ca +3Mg (all values as oxide, except N).
So the complete Kristalon red if you would blend the 3 ingredients above would be quite exactly 12+6+2 oz (instead of 8+8+4) (if anyone cares, maybe it could be a better mix worth trying).

Later edit: looking at the cheapest prices on amazon, without shipping, comparing 4 complete fertilizers in reasonably bulk quantities (~5lbs or more/ingredient):
masterblend mix (self made, using 3 components, 7.5-7.5-15+ everything else) - 3.3usd/lb
miracle grow tomato complete (9-4-12+everything) - 3.1 usd/lb
texas tomato food (4.0-2.9-6.7 + everything, pretty much half strength of masterblend) - 2.3 usd/lb (assuming a sensible density of 1.3, no idea what the actual density is)
kristalon red ca (not available in usa) (11-11-24+everything) - 2.1 usd/lb

So in USA, miracle grow seems even cheaper than the powders somehow and it's premixed, which is a pro for the small grower who doesn't want to tweak anything, but not for a pro probably. TTF is not bad price but half strength, so basically the most expensive.
This doesn't tell the whole story, I have not compared how they actually perform, just comparing main raw numbers.

Last edited by zipcode; August 24, 2017 at 08:49 AM.
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