# Lucas Formula: Add Back Calculator!



## Smot360 (Apr 17, 2011)

> * https://www.rollitup.org/hydroponics-aeroponics/4387-lucas-formula.html *





> *addback calculator - (for advanced users) (smot360- add back calculator1 )
> 
> say you were running the 0-8-16 formula, at 0.7 conversion with a 22 gallon res. When you first fill it up, your ppm will be around 1330.
> 
> ...


The "*add back calculator 1"* when you have a 50 gallon tank, and you are trying to reach a target ppm of 600 and your current ppm s are at 450 the calculations come out to say 100 ml of micro and 200 ml of bloom....

Now As you can see the "*add back calculator 2"* when you have a 50 gallon tank, and you are trying to reach a target ppm of 600 and your current ppm s are at 450 the calculations come out to say -250 ml of micro and -500 ml of bloom?? And then with a 30 gallon tank you are lookin at -90 ml of micro and -180 of bloom??? I do not understand these conversions....I was wondering if someone could help me out with this formula or maybe I am doing it wrong. 

Which Formula/ Calculator is right! Can Anyone help me out PLEASE!​

If Anyone Wants to use these conversion methods quickly, I have Built and attached at the bottom; 2 Calculators Based on the above formulas

View attachment 1555754
View attachment 1555756


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## Smot360 (Apr 18, 2011)

Seriously no one has anything to say?


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## ExDex1x1 (Apr 19, 2011)

using markdown math is the way to go. This will give you a low estimate of how much to add. Calculate, mix, adjust. Its always easier to add more than it is to try and dilute your concentration so go for a lowball number and work from there. Keep in mind this isn't precision math and experience with your individual nutrients will always be more effective than calculations. Do rough quick math and let your experience fill in the gaps.


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