The nutrient formula N P K reads as follows in the USA:
N= % total Nitrogen
P= % P2O5
K= % K2O
Some times a Formula gives only a ratio between N:P:K
What is important is the total dissolved substance or nutrients and this can be measured by the EC meter.
There are many recommendations of nutrient formulas specific for each crop and for different stages of growth, Seedlings stage, Vegetative stage, Flowering and Fruting stages. Also every grower adjusts the particular nutrients to his or her needs. I would read further in the subject of plant nutrition and consult with the Agriculture Agent in your area for recommendations.
Here is a good website that may give you some info.

http://hydro-gardens.com

Safwat Zaki
Horticulturist

Thank you, Safwat,

In the book, "How to Hydroponics", there are general formulae; 9.5-5.67-11.3 for growth, 8.2-5.9-13.6 for fruting, and 5.5-7.97-18.4.
But the composition of this formulae from chemicals(such as Ca(NO3)2, KNO3,,,) are wrong in the same book. You can find that if you trace the amount of P, which are provided only by KH2PO4.
This is the only source I could get, but wrong.

Help Me!

Thanks and regards,

Hi, I just purchased some commercial products from Southern Agriculture. The smallest size of their hydroponic special product comes in a 25 pound bag. Also, some Epsom salt and some Calcium nitrate is added to complete the basic nutrient. The Calcium Nitrate comes in a 50 pound bag. Epsom salts are purchased at any drug store in small packages. I got mine at Wal-Mart. Now, to make 5 gallons of nutrient solution, it takes 4 teaspoons of the So. Ag. 5-11-26, 1 teaspoon of Epsom salts (fully disolved in enough water to be a liquid,and 2 teaspoons of Calcium Nitrate, (also disolved in water prior to mixing). So, I take 1 gallon of water and mix in the Ag So hydro mix. Another gal of water to disolve the Epsom salts, and finally a gallon of water to disolve the Calcium Nitrate. That leaves 3 gallons of plain water to start with in the tank. The instructions say that the So Ag 5-11-26 must be added first to the tank with the 3 gal of water and mixed. Next mix in the gal with the Epsom Salts to the tank and mix. Finnaly, add the gallon with the Calcium Nitrate last and mix. The result is 5 gallons of nutrient ready for use. This is only a general guide. The instructions also say that young tomato plants could be started out using 1/2 strength, and full strength at middle growth. I am going to start out at 1/2 strength to start and go up in strength as the plants grow. This mix should have the following PPM. N 150 PPM, P 52 PPM, K 250 PPM, Ca 121 PPM, Mg 52 PPM, AND A BUNCH MORE TRACE MINERALS RANGING FROM .1 TO 3 PPM. I intend on making the solution full strength and then taking a measurment with my cheap meter, and also a half strength mix and measuring that. Because I seem to have SO MUCH of the ingredients, I will probably be changing the nutrients when the readings change by 10% or so. The cost of the 25 pound bag of the 5-11-26 was just under $20. The 50# bag of Calcium Nitrate was $13. The Epsom salts was a couple bucks. To make a 1000 gal of the mix, the ammounts are 8 pounds 5-11-26, 2 pounds Epsom salts, and about 5 1/2 pounds of Calcium nitrate. So, it would seem that I will be able to make about 3000 gallons approx. for a cost of about $35 dollars. (I should live so long.) I guess that if you have to have the ingredients shipped, you might end up spending another $20 dollars shipping for a total of around $55 dollars, or about 2 cents per gallon for a known good professional product. I hope that this will help you decide how to handle the nutrients. I will be glad to share the results once I have my new system set up and working. chuck

Here is a link that might be useful: Hydro expirements

I am very new to hydroponic's and I was wondering if I had a 40 ft tube, could I grow different veggies in one tube.
Like tomato's, watermelons, canalope, peas, beans???
Thanks

Tim

Hi Tim, I tried a bunch of different things over the past couple years. You might get some ideas from my website of construction projects. I tried several kinds of tube systems using inexpensive 4" plastic drain pipe. chuck

Here is a link that might be useful: Some hydro projects to expirement with

You can always try several different types of plants. You will probably have better luck if you choose plants that like a similar level of nutrient strength. Say lettuce and peas might grow in the same nutrient level while tomatos and peppers like a stronger mix.

Although preparing a balanced N-P-K solution sounds somewhat confusing, itâÂÂs quite a simple process when you have the right constituents and instructions. The formula requires you to mix 1 quart of full strength liquid plant food and 3 quarts of water in a clean container.

This post was edited by HassDan on Wed, Jul 9, 14 at 12:03

Since all the nutrients are supplied through water in a hydroponic system, it remains highly important to prepare a hydroponic nutrient solution using the right ingredients. The best commercial formulations involve a mixture of flexible plant nutrients that are suitable for most plants including tomatoes, marijuana and almost all vegetables that can be grown hydroponically.

Regardless of which brand you use, make it a point to add balanced amounts of nitrogen, Epsom salts and Calcium Nitrate. The key is to water your plants with plain water and keep the pH level within the grow room ideal, depending upon which stage/phase your plants are in.

The nutrient make-up, strength and PH should be geared to the plant and hydroponic method used. No need to use plain water unless you have a salt build up which will likely be due to gardener error, aka, not gearing the nutrient strength to the hydroponic method used.

Nitrogen is a gas :)