Ok, so to play a sort of devils advocate... I believe you, and trust your expertise (I recognize you from another forum, b/c of another thread in which you "revealed yourself" :coverlaugh: not to mention, you've always given sound advice here as well), but if chlorine is important, then how do growers that use RO, or distilled water only, not have problems with chlorine deficiencies? Or do they just not know it? Or, is it just that it's required in such a low amount, that it would take years to even recognize/see the symptoms? And what are the symptoms of a chlorine deficiency? I'm assuming that fertilizer meant to be used with RO/DI/Rain water doesn't have chlorine added... A fertilizer such as MSU brand, for example... Am I wrong in assuming that? :hmm you've got me curious! :waving

Heheh, :blushing: sorry for all the questions... Please don't take it the wrong way, I just wanna learn - and love to learn - as much as possible, and haven't (to my recollection) heard chlorine mentioned as a necessary micronutrient ;)

Interesting question, Mary Linn.

Here is a table of plants' 17 essential elements, and yes, Cl is one of them.
List of Essential Elements

I assumed that MSU has all 14 elements (3 are from atmosphere and water, C, H, O), but you are right, it doesn't have Cl and Ni. I don't know why Cl isn't in MSU (Cl isn't usually taken from air as far as I know). My RO system doesn't remove all ions, so mine probably contains residual Cl. Maybe whatever media (inorganic or organic) contain enough Cl?

Dyna-gro Grow does contain all 14 elements + 2 beneficial elements.

This is exactly why I started using Neptune's Harvest with every second or third watering (the other 2 are K-Lite and DG Grow). While the inorganics are convenient and inodorous, I don't think that a powder combination can adequately provide all that a plant needs. So between the 3 of them, all at very low doses (no more than 20 ppm N), I figure the plants are getting a well balanced diet. And I'm sure NH has plenty of chlorine.

One couldn't run a commercial greenhouse this way, but for a home collection, alternating fertilizers is very doable.

Don't forget that some fertilizers include potassium in the form of Potassium Chloride, just as one example of how chlorine may be provided.

Rain water also contains chlorides:

Rainwater Chemistry Across the United States

AMS Journals Online - THE CONCENTRATION OF CHLORIDE, SODIUM, POTASSIUM, CALCIUM, AND SULFATE IN RAIN WATER OVER THE UNITED STATES

My plants have seen nothing but MSU RO or K-Lite for the last ten years, neither contains any nickel or chloride raw materials, I use RO extracted from well water, and I have seen no signs of deficiency.

I believe silicon is also in that category of "essential/nobody knows the amount needed/nobody has ever seen signs of deficiency"

Most living organisms don't utilize the form of chlorine that's added to our tap water or used to make Clorox. Plants use an ion of chlorine known as chloride. Chloride is found in many fertilizers and in tap water. It is only needed in very small amounts.

@ Mary Linn

I think your question about RO is an excellent one! (We all learn from asking questions; I certainly do! So, I never take questions the wrong way, and I always appreciate the sound advice that I see you offering to others!)

I have never run a chemical analysis of RO water (perhaps Ray has, as I know he sells these systems). I would be curious to see the results of such testing. I suspect (but don't know for sure) that RO reduces the concentrations of various ions in the water, but maybe does not eliminate them entirely? Maybe Ray will see this & post some test results. Naoki has suggested that this is what her RO system is doing.

I currently water with rain water whenever I can. I think that if you are using rain water or RO water, you are also getting some Cl from the atmosphere. As Naoki, ALToronto, and Jayfar have suggested, a lot of elements are also provided in our fertilizers. We all make different choices regarding what fertilizer to use, but as long as the plants are getting the elements needed to grow well, the plants will be healthy.

Your plants have also been getting KelpMax, which contains lots of trace elements that the manufactured inorganics don't have.

I would point out that ground water, including well water, often contains naturally-occurring chloride.

I sampled a spring recently that had very low total dissolved solids (only 27 ppm), but still had 2.7 ppm chloride. Spring water is also classified as ground water, BTW.

It is not unusual to see ground water or surface water with chloride in the 10 to 100 ppm range; the limit for drinking water is 250 ppm, but only because water with greater than 250 ppm Cl begins to taste funny (still safe).

---------- Post added at 09:59 AM ---------- Previous post was at 09:56 AM ----------

Ray, do you have an analysis of your RO water and a comparison to the water before the RO? This would be interesting to see if you have it.

What an interesting thread and much to learn from it in different issues :thanx:

I am not at all an experienced orchid grower, all my previous orchids have been "in the wild" only, so I can't give an opinion about fertilizing. But I would like to comment on the word "organic":

It means by definition that something is grown in a "natural way": no sewedge sludge or chemical pest control, no genetical engineering, no synthetic fertilizers used; for plants they have to be grown in soil that has not been treated with any of these for 7 years (that's in my country, laws may vary). For animals and their products: their food has to be organic, they need access to outdoors, no antibiotics,…

That means that a fertilizer is not organic because it uses chicken droppings. It's organic only if the chicken and its food are grown according to organic standards.

As for an element in a fertilizer: if you extract a certain element from something organically grown, chemically it is in no way different than an element produced in a lab.

In Canada "Le Paradis des Orchidees" in Montreal is producing their own organic fertilizer. How organic it really is - no idea :hmm