This is what the full paper has to say about the lower levels of protein, amino acids, and N. Title of subsection: "Proteins, amino acids, nitrogen and nitrate/nitrite" "The concentrations of proteins, amino acids and N (which are known to be positively correlated in plants) were found to be lower in organic crops, and this is consistent with the results of previous studies that have linked lower protein concentrations to lower N inputs and N availability in organic crop production systems( 61 , 62 ). The nutritional significance/relevance of slightly lower protein and amino acid concentrations in organic crops to human health is likely to be low, as European and North American diets typically provide sufficient or even excessive amounts of proteins and essential amino acids. Also, while some studies concluded that protein content in most European and North American diets is too high and that this contributes to the increasing incidence of diabetes and obesity( 63 ), other studies reported that increasing protein intake levels may be a strategy to prevent obesity( 64 ). Therefore, the lower protein and amino acid concentrations found in organic foods are unlikely to have a significant nutritional or health impact. The higher $$NO _(3)^( - ) $$ and $$NO _(2)^( - ) $$ concentrations in conventional crops are also thought to be linked to high mineral N inputs, as both $$NO _(3)^( - ) $$ and $$NO _(2)^( - ) $$ are known to accumulate in plants under high-mineral N input regimens( 65 ). The higher $$NO _(2)^( - ) $$ concentrations in conventional crops/crop-based foods are nutritionally undesirable, as they have been described to be risk factors for stomach cancer and methaemoglobinaemia in humans( 65 ). However, while increasing dietary $$NO _(2)^( - ) $$ intake levels is widely considered to be potentially harmful for human health, there is still controversy about the potential health impacts of crop-based dietary $$NO _(3)^( - ) $$ intake( 65 ��" 67 )." Please keep in mind that the above was written by scientists in the field but the statements had to be approved by the reviewers and the editor. Here is a link that might be useful: link to full scientific paper quoted above

you will need to replant repeatedly for a continuous supply...

Yes it is acceptable to add more get your ppm up,that's what we use a meter for.You won't mess it up by adding.Unless you put way to much in.What I do is keep a record of how much I put in and then next time you redo your tank you'll have an idea how much to start with. mudcat

Hey I didn't intend to start a chemical vs. organic war! Yes active sewer contains microbes that make all the nutrients available to the plants and the treatment process of aeration provides the oxygen for the roots. If the churning sewer was contained below in the root zone I would have no problem eating what grows above as plants don't transmit pathogens from the roots to the leafy and fruit portions. This brings to mind the e-coli tainted spinach in the news. It was undoubtedly contaminated by rain splash from the soil or direct contact from contaminated foliar sprays. Back to the subject though. I plan to use chemicals in my patio hydro system and have no problem with them as such, just think excessive flushing and changing out entire reservoir systems every two weeks or so like I have seen written in various places is bunk. You don't need to flush any hydro system prior to eating any produce because the plants only take what they need from the solution to grow from whatever source. Japanese have been using human waste in gardening for centuries but they know not to get it on the plant parts they eat. If your system were not covered and allowed to splash the plants with chemical salts, they would surely be unfit to eat because of chemical residue. Yes I'm an old hippie...use less chemicals by being smart and not needlessly wasting them or dumping them out in places where they might do environmental harm! Use them wisely and they will produce as intended... On the other hand, if I can cause organic materials and methods to produce the same results without danger or likewise environmental harm, I will opt for organic.