Nutrient Calculator Introduction
This program is designed for a particular brand of Hydroponic
Nutrient solution in which the user can calculate how much nutrient solution is needed to add to a specific volume of water (Target
Conductivity). The program takes into consideration any natural
Raw water Conductivity to achieve any Conductivity Factor value
desired by the user in a Tank of water. This can be used to gauge the
strength and amount of feed required measured in units either as
CF, EC, ppm (EC x 500), or ppm (EC x 700) (all of which are
supported by the Nutrient Calculator) for plants at different stages
of growth in hydroponic systems or soil or Coco set ups. The units for liquid volume measurement supported by the Nutrient Calculator are Litres & millilitres (Metric), Quarts & teaspoons (USA). The Nutrient Calculator is designed to work with Growth Technology nutrient
solutions only and calculates their main Hydroponic, Soil and Coco nutrients.
There are three variants of water that can be taken into consideration with use of the Nutrient Calculator; these are Tap Water, Rain Water and De-Ionised Water. Tap Water is set as
default to calculate the users Target Conductivity. (Smartphone Apps only) For rain water
simply subtract an EC value of 0.05 from your Target conductivity and for Deionised water
subtract an EC value of 0.1 from your target conductivity. (EC values of 0.05 and 0.1 or their
equivalent in supported Nutrient Calculator Units)
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BEFORE YOU USE THE NUTRIENT CALCULATOR
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Always check your Conductivity Factor measuring device before and after use
and calibrate on a regular basis. A good quality affordable Digital meter type
such as the Hanna HI 9813-6 (Or later model) is recommended for use. This device displays the readings in EC and TDS. (Electrical Conductivity and Total Dissolved Solids)
Know your tank volume to your fill level. (Litres or Quarts (USA)) Good accuracy
of your tank volume is essential.
Try to get consistency between your liquid measuring devices (Jugs, Syringes,
Beakers and Buckets etc.) as close as possible i.e. they are all measuring the
same in quantity. Unfortunately, more often than not, you may find that buckets, measuring jugs, measuring beakers and syringes tend to differ in volume
measurement substantially. If you are having difficulty achieving your target
conductivity and the error in your measured tank conductivity is relatively constant after 2 or 3 uses of the Nutrient Calculator, then the most probable cause
is due to either: (a) Defective volume measuring container, jug, beaker, syringe
or bucket etc. (b) Incorrect tank volume measurement.
A way to overcome this problem is to simply customise your target conductivity
value to work with the volume containers and measurements you have, for example:
After Use of Nutrient Calculator.
Example (a) Your Target Conductivity was EC = 1.5
But your Measured Tank Conductivity is EC = 1.57 (Fine Tune to EC = 1.5)
Next Time Simply subtract the excess error from your Target Conductivity (EC
1.5 – EC 0.07)
Therefore Target conductivity is EC = 1.43
Measured Tank Conductivity is EC = 1.5 = Original Target Conductivity.
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Example (b) Your Target Conductivity was EC = 1.2
But your Measured Tank Conductivity is EC = 1.15 (Fine Tune to EC = 1.2)
Next Time Simply add the deficit error to your Target Conductivity (EC 1.2 + EC
0.05)
Therefore Target conductivity is EC = 1.25
Measured Tank Conductivity is EC = 1.2 = Original Target Conductivity.
The error will remain relatively constant and can be used to adjust your proposed Target Conductivity, either negatively or positively (Depending on measured Tank Conductivity) to achieve the required Target conductivity. This compensating adjustment applies to all further use of the Nutrient Calculator as
long as the user continues to use the same liquid volume measuring devices
and continues to use the same chosen nutrient solution. Any change in these
factors may result in a different conductivity error that can be dealt with by repeating the same process.
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know how the Conductivity value being either too high or too low in your tank
can have an effect on the plants health and physical appearance. Regular observations on the plants themselves are a must to avoid damage to your plants
health from incorrect Conductivity values for the different stages of growth.
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Know the Raw Water Conductivity value for your local water supply. For accuracy test your local water supply with a Conductivity meter that can measure to at
least one decimal point. For an accurate reading with instruments that are temperature dependent we recommend that the instrument probe is left submersed in the water for a minimum of 3 minutes ( 5 minutes is even better). Remove any air bubbles that may be trapped around the probe sensor by gentle
agitation before a final reading is taken.
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MANAGING YOUR NUTRIENT SOLUTION
When temperatures get up towards 100F (38 degrees Celsius) nutrient uptake tends to Decrease quite
a lot. The plants are interested in water, but not so much dissolved ions.
There is a complicating factor in this as well. Nutrient ions are not all absorbed the same way. It is
quite a complicated thing to get ions past a cellulose wall and then through a phospholipid bi-layer
and only then into the cell. There are 3 mechanisms for mineral absorption and a dozen minerals and
each of these 3 absorption mechanisms behave differently under different environmental conditions.
The classic example here is when it gets a bit hot and humid; calcium and boron absorption can stop
completely while potassium and nitrate seem to have their absorption unaffected by those conditions.
Nutrient absorption is not a constant process. Different nutrients have different mechanisms of
absorption and these mechanisms can be affected by environmental conditions. The end result of all
this is that nutrient solutions can get out of balance and what we think we have in the tank isn’t
necessarily so. A fresh tank of nutrient solution starts to get out of balance in a process that starts
within minutes of it being exposed to the plants roots. Nutrient solution management has never been
an exact science. It operates on rules of thumb more than anything and unless the grower is prepared
to fork out for selective ion electrodes and injectors for each nutrient element it will continue to be.
When it comes to purchasing multi packed nutrient solutions where all the various nutrient elements
needed to sustain the plants health are packed into one container of solution, it’s worth bearing in
mind the following. It would be very difficult for the “hobby grower” to segregate the various
elements of nutrient needed from the container of solution to solve the Nutrient solution
management problem. Usually, the only tools available to the hobbyist to manage his/ her nutrient
solution, are measuring devices such as either a Truncheon, or a CF / EC /ppm probe meter, or
perhaps you may own a Brix refractor meter. None of these devices will tell you which element of
nutrient your plant needs at any particular stage of growth. All the hobbyist can do with these devices
is take Conductivity measurements which will be one of 3 measurements for Conductivity values, i.e.
higher than what it should be, lower than what it should be, or, the measurement is reading correct.
The hobbyist would naturally dilute with fresh water for the first measurement, add nutrient solution
for the second measurement and for the third measurement either leave “as is”, or top up with fresh
water and nutrient solution at the same ratio of what is in the tank. What the Nutrient calculator does
is put the user in the right ball park for nutrient solution management right from the start with the
initial tank set-up. If the user gets to the stage in which the user is having to use the Tank Top Up
procedure of the nutrient calculator where the user is running at his/her plants full strength of
nutrient and the user is topping up at the same Conductivity ratio as what is in the tank, then it is
worth bearing in mind the problems of nutrient solution management as mentioned in the previous
paragraph. To avoid this problem complete water change is recommended every 7 to 10 days
maximum and using the tank top up procedure after this recommendation will only buy you a short
period of time before the effects of poor nutrient management become apparent with your plants.
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