HYDROPONIC LINKS

This first one has amounts to use:

http://res2.agr.ca/harrow/bk/tomch9.htm

http://www.hydromall.com/grower/suite101/fertilize_me_baby.html

Most commercial Hydroponic growing operations use premixed fertilizers to reduce the chances of nutrient defficiencies occuring caused by human error and to reduce the labour involved in ordering and preparing nutrient solutions from scratch. Various recipes used for lettuce, tomatoes, and cucumbers can be found at:

http://www.cals.cornell.edu/dept/flori/lettuce/stock.html
http://www.usu.edu/~cpl/nutrwht.html
http://res.agr.ca/harrow/bk2/cuke1a.htm
http://res.agr.ca/harrow/bk/tomch9.htm
http://www.ag.arizona.edu/hydroponictomatoes/nutritio.htm
http://members.tripod.com/Client_Profile/l_form.htm
http://www.biotron.slu.se/bio3375.htm
http://www.np.edu.sg/~dept-bio/sssc/nutr.html
http://www.hbci.com/~wenonah/hydro/nitragen.htm
http://www.atlantic.net/~elifritz/hydroponics.htm

Another good source for recipes is the Journal of Plant Nutrition, esp. Vol. #21. Issue #10 which compares 12 different solutions.

The units of measuring concentration are Siemens and Mhos where 2 microSiemen(uS)=2 micromho(umho)=~1 ppm(approximation). Siemens and Mhos are units of Electrical Conductivity (EC) as described in an earlier article and are reciprocals of resistance (Ohms) as the EC of solutions increases linearly with nutrient concentration. Typical nutrient concentrations are from 1000-3000 uS/cm (~500-1500 ppm) depending on size, type of, and growth rate of the plants.