sproutco said:Many growers buy pre-made concentrates of fertilizer. They add so many mililiters to a gallon of water. These fertilizers are very expensive. You can make your own nutrient solutions from scratch very easily and it is alot of fun. To do this will require a gram scale accurate to .1 gram and a calculator.
When you see the numbers 10-10-10 on a fertilizer bag, they represent 10% nitrogen, 10% phosphorus with oxygen, and 10% potassium with oxygen. To convert the phosphate with oxygen to just pure phosphorus, you multiply by .43 This would really be only 4.3% phosphorus. To convert potassium with oxygen to just pure potassium, you would multiply by .83 This would really be only 8.3% potassium. (.43 x .1=.043 and .83 x .1=.083)
You will have to learn parts per million (ppm). 1 gram or 1000 milligrams of a pure element in 1 liter of water is 1000 parts per million (ppm) For example, I put 500 milligrams of pure nitrogen into 1 liter of water so that would be 500 ppm nitrogen.
Having these weights, measurements, and basic math will be handy:
inverse of a number is 1 divided by the number so inverse .2=5 that would be 1 divided by .2=5
100%=1 so 50% would be .5
3.8 liters of water=1 gallon
128 ounces(oz)=1 gallon
454 grams=1 pound
1000 milligrams (mg)=1 gram(g)
2 tablespoons=1 ounce=6 teaspoons
Plants require the macronutrients(require alot) nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur to grow. They also require the micronutrients (require very little) iron, manganese, zinc, copper, boron, molybdenum, and chlorine to grow.
Common ranges in nutrient solutions for these elements are in parts per million: nitrogen 100-200, phosphorus 30-50, potassium 100-200, calcium 100-200, magnesium 30-70, sulfur 50, iron 2-12, manganese .5-2, zinc .05-.1, copper .01-.1, boron .2-.4, molybdenum .05, and chloride 5.
There are hundreds of nutrient solutions to try and copy. There are so many because most of them work. If plants only grew with one type of nutrient solution or soil, the planet would have few plants. Hoagland's nutrient solution, named after Dr. Hoagland at the University of California, is probably the most famous. I am going to explain how to make Johnson's nutrient solution. It works well with indoor plants in medium light intensity. It is in parts per million:
105 nitrogen, 33 phosphorus(p), 138 potassium(k), 85 calcium(ca), 25 magnesium(mg), 33 sulfur(s), 2.3 iron(fe), .26 manganese(mn), .024 zinc(zn), .01 copper(cu), .23 boron(b), and .007 molybdenum(mo)
You would need the following ingredients to make this:
monopotassium phosphate 0-52-34
potassium nitrate 13-0-44
calcium nitrate 15.5-0-0 plus 19% calcium
magnesium sulfate/epsom salts 10% magnesium and 13% sulfur
Each of the micronutrients with iron, manganese, zinc, and copper chelated with maybe edta to keep them soluble and not oxidize. Compound 111 by Scotts is an example of a micronutrient mix you could use that would contain all the micronutrients rather than weigh them out individually.
You can find all the ingredients by checking around town at hydro stores and garden centers to save shipping on bags. You could also get the individual micronutrients from www.hydro-gardens.com They would also have the major elements as well.
To start, you will want to figure out phosphorus. We will use the monopotassium phosphate (0-52-34) 33 ppm p (33 mg in 1 liter of water) x the inverse of .23 Remember we had to convert 52% phosphorus on the fertilizer bag to real p by multiplying by .43 The inverse is 1 divided by the number (your calculator may have a x-1 key; .23 x-1 key). So, inverse .23=4.3 33 x inverse .23=143 mg per liter of monopotassium phosphate. For 1 gallon, multiply by 3.8 So, 543 milligrams(mg) or .5 grams(g) would be added.
We also added potassium with our phosphorus. To find out how much just work backwards. 543 mg divided by 3.8=143 mg x .28 (notice that this is not the inverse; we had to multiply 34% potassium with oxygen to pure potassium by multiplying by .83; .83 x 34=.28) so 143 mg x .28=40 ppm potassium was added.
Our nutrient solution requires more potassium(k). 138k-40k=98 ppm k still needed. We will use potassium nitrate(13-0-44) for this. Remember to convert the 44% to pure potassium by multiplying by .83=36.5% pure 98k x inverse .365=268 milligrams in a liter of water. For a gallon, 268 x 3.8=1020 milligrams or about 1 gram of potassium nitrate.
We also added nitrogen with our additional potassium. Just work backwards. 1020mg divided by 3.8=268 x .13 (13%nitrogen)=35 ppm nitrogen
We still need more nitrogen
If you work backwards like before you will see that we also added 85 ppm calcium with the nitrogen.
Next magnesium using the magnesium sulfate/epsom salts.(10% magnesium and 13% sulfur). 25 ppm x inverse .1=250 mg in a liter. For a gallon, 250mg x 3.8=950 milligrams or about 1 gram of epsom salts.
If you work backwards like before you will see that we also added 33 ppm sulfur with the magnesium.
Those fertilizers with multiple elements in them are tricky. The rest of the nutrient solution is easier. It uses individual elements for the micronutrients.
iron: I have an iron chelate 13% fe. I want 2.3 ppm iron. 2.3 x inverse .13=17 mg per liter. To find a gallon, 17 x 3.8=67 milligrams or .067 grams of the iron chelate.
For the rest of the micronutrients, your source of these might be boric acid(17%b), manganese chelate(13%mn), zinc chelate(15%zn), copper chelate(14%cu), and molybdic acid(50%mo). You would do the math just like the iron...its straightforward.
boron: We want .23 ppm boron(b) x inverse .17(from boric acid 17%b)=1.35 mg per liter. For a gallon, 1.35 x 3.8=5.14 mg or .005 g boric acid.
manganese: We want .26 ppm manganese(mn) x inverse .13(from mn chelate 13%mn)=2 mg per liter For a gallon, 2 x 3.8=7.6 mg or .0076 grams mn chelate.
For the molybdenum, you will use very little. .007 ppm mo x inverse .5(from molybdic acid 50%mo)=.014 mg. For a gallon, .014 mg x 3.8=.05 mg or .00005 g. This is so small and that is why the micro's are in a stock concentrate (i'll explain stocks later) . If you make your stock for 64 gallons, .05mg x 64 gallons=3.2mg or .003 grams. What you could do is take .1 gram or 100mg molybdic acid in 8 oz of water(1 cup) and then put 11/2 teaspoons out of this into your 64 gallon stock. (6 teaspoons=1 ounce) .003 g divided by .1 g=.03 so .03 x 8 ounces=.24 ounces
Zinc and copper are also used in small quantitys like molybdenum. Put like .1 gram or 100 milligrams of each of the chelates into 8 ounces of water just like what we did with the molybdenum. Then add some out of this into your stock.
zinc: .024 ppm x inverse .15 (zinc chelate 15%zn)=.16 mg For a gallon, .16 x 3.8=.6 mg For 64 gallon stock .6 mg x 64=38.4 mg So you could put .1 gram or 100 milligrams into 8 ounces of water(1 cup) and then take 38.4mg/100mg x 8=3.07 ounces into your stock jug.
Copper(cu) is "double diluted" like zinc and molybdenum were. We want .01 ppm cu x inverse .14 (from copper chelate 14%cu)=.07 mg per liter. For a gallon, .07mg x 3.8=.27 mg of copper chelate. To add this to a 64 gallon stock of micronutrients: .27mg x 64 gal=17 mg or .017 grams. Put .1 gram or 100 milligrams of cu chelate in 8 ounces of water. Then add 17mg/100mg x 8 ounces=1.36 ounces of this into the 64 gallon micro stock.
Although not in the formula, plants require a small amount of chlorine to grow. You can add 2 ppm chloride by using table salt in with your micronutrients. Table salt is 60% chloride. 2 ppm x inverse .6=3.3 mg per liter For 1 gallon, 3.3 mg x 3.8=12.5 mg or .01 grams
Weighing the fertilizer takes some time. It is best to get 3 quantity of 1 gallon milk jugs or bottled water containers and make a stock. This is just concentrated fertilizer. Put the calcium nitrate in 1 jug, micronutrients in another, and everything else in the last jug. You will not have to weigh fertilizer all the time. The micronutrients especially have to be made into a stock because so little is used. It would take an expensive scale to measure out the micronutrients for just 1 gallon. Making the concentrates strong enough to make 64 gallons of finished nutrient solution makes things easy. Then when you would need to make 1 gallon, you would add 2 ounces out of each stock. For example, we wanted 1.7 grams of calcium nitrate in 1 gallon of water. You would make a stock 1.7g x 64 gallons=109 grams of calcium nitrate in your stock jug. So each 2 ounces of stock would contain 1.7 grams calcium nitrate. If you wanted to reduce your nutrient solution to 3/4 strength(79 ppm n), you would only use 1.5 ounces per gallon of water out of each stock. If you wanted to raise the strength to 1 1/2 times(158 ppm n) you would add 3 ounces per gallon of water out of each stock.
You can make adjustments to the nutrient solution by just reducing or raising the total strength of all the fertilzers used from each stock. You would want 3/4 strength for seedlings(79 ppm n) and 1 1/2 times strength(158 ppm n) for extra growth. The micronutrients used for this formula are weak except iron. You could easily double the amount used except for maybe iron. For flowering, you could just reduce nitrogen to 75 ppm and not all the elements. To do this easily, just use less calcium nitrate at the end of getting all the nitrogen for the solution. If you do the math, you will see that it would be 1 gram instead of 1.7 grams in a gallon of water. Simply reduce the amount you use from your stock jug by 1/1.7 or 59%. If full strength calcium nitrate was 2 ounces out of your stock for 1 gallon of nutrient solution, you would only use 1.17 ounces. Of course reducing nitrogen like this would also lower your calcium.
It is best to double check all your math for errors. Also, make sure you have included all the elements required and not left something out like a micronutrient.
A note to soilless media growers using dolomite lime in their mixes for ph control...you would not want to use this nutrient solution because it contains alot of calcium and magnesium that is not required. A way to get around this would be to use very little lime like 1/2 teaspoon to a 6" diameter pot or 2 tablespoons per cubic foot of soil and get the calcium and magnesium through the nutrient solution. Because of national security, we are no longer able to get ammonium nitrate and are forced to get some of the nitrogen from calcium nitrate. So, the trend will be to use little lime.
Growers using hydroponics with a reservoir: Plants will use water/fertilizer and the level will drop. You can monitor the electical conductivity(ec) of the nutrient solution to know how strong this water plus fertilizer to be added back should be. Just compare original ec to current ec. Then raise the ec to original levels with the nutrients/water. Micronutrients should not be included in this. A rule of thumb would be to use 1/4 to 1/3 strength nutrient solution without micronutrients to top off the reservoir. In time (few weeks), it would be wise to completely replace the solution in the reservoir and start with fresh nutrient solution.
You will want to adjust the ph of the nutrient solution to 6 or slightly lower. Here's a link for what to use:http://www.icmag.com/ic/showthread.php?t=31294
Now that you understand the basic way to make a nutrient solution, you could copy any formula or make your own unique recipe. If you make your own recipe, use the common ranges previously listed for the elements and try to maybe achieve these ratios: 1.5-2:1 potassium to calcium and 3-4:1 calcium to magnesium. Also, use as much nitrate nitrogen as possible rather than ammonia or urea nitrogen. You could do things like raise phosphorus during flowering if desired and make a "bloom booster". If you ran into an iron deficiency, you could raise just iron levels. Once I raised my manganese levels from .55 ppm to .65 ppm and called it my "I can't drive 55" formula. (Sammy Hagar song)
This thread is interesting in that it shows the parts per million of common "store bought" fertilizers that everybody seems to be using including the popular lucas formula. While it only lists nitrogen, phosphorus, potassium, and magnesium, you can can get an idea of what is in them. Using my basic directions, you could copy any of them. This thread also has a link to common ranges of nutrient solutions specifically for mj. http://www.icmag.com/ic/showthread.php?t=21119
Reference books that show calculations and other nutrient solutions to try:
Hydroponic food production, a definitive guidebook of soilless food-growing methods by Howard Resh
Hydroponic nutrients-easy ways to make your own by Edward Muckle
Hydroponics: a practical guide for the soilless grower by Benton Jones
I hope you have found this information useful. Let me know if something needs to be clearer or you have any suggestions.
octodiem said:
Yee, Hah!.. 
Good 1...
sproutco said:
