"Good Quality" water?

[Undergrounder]

What makes good quality water to use on orchids? I know the total dissolved solids of my drinking water is pretty low (around about 100ppm) and the pH is 7.5 - 8.

But what micronutrients are required in tap water if i just want to use a 'regular' fertiliser?

I've attached a printout of our local water quality. Mine is under the 'Prospect' source. Can someone have a look and tell me if anything stands out about it as something to be corrected?

Mostly my plants grow very well, although a few of my more tricky Phal. violacea species have developed yellow colour on the leaf tips (not die-back, just plain yellow colouring) and i was wondering whether it was some kind of nutrient deficiency.

thanks!

[nhman]

G'day!
First question is probably the key: What are you using for fertilizer? You NEED something more than just water for most orchid species to grow, develop and bloom well. If you are not using a fertilizer designed around the water base that you are using, that would be the simple answer right there.
Secondly, in specific answer to your question, not bad water from a public source, (IMHO based upon evaluation of our home water sources over the years)- sodium isn't that high, but may build up in potting media (depending upon what you are using for media) and that may eventually cause problems.
Again, "may", "can", etc.
Reverse osmosis water is "pure" and might be a benefit if questions arise over public water supplies.
Hope that this helps.
Perhaps someone with a more chemical background than I could more critically evaluate your chemical analysis.
Best of luck!

[Undergrounder]

Thanks that's very helpful!, so can i assume its got the micronutrients present that would allow me to use a 'regular' fertiliser? (as opposed to requiring a hydroponic fertiliser?)

I know i should add the details of the fertiliser i'm using. But i am using a fairly balanced liquid fertiliser at about 150-200ppm strength. Next time i'm downstairs i'll find out the nutrients in it.

And i'm using purely inert medium, either LECA or perlite.

[Ray]

nhman is dead-on! There is no water supply on earth that provides sufficient nutrition for most plants.

Most of the time, "good" is used as a measure of purity and pH. From a purity perspective, yours looks OK, but the pH is a bit high, with something in the 5.5-6.5 range being better.

As to the chemistry, I have calculated the ionic contributions of three fertilizers - Dyna-Gro "Grow", and the Greencare "MSU" formulas in a 125 ppm N solution. As the MSU RO formula is used in water containing nothing (and it's a really good product), I think it is a reasonable target for what the final fertilizer solution should look like.

Based upon that, you can see what is NOT in your water supply and look for a fertilizer to fill that gaps.

(Don't sweat the ammonium versus nitrate nitrogen levels, as they are used to contrl the pH based upon the water source.)

[orchids3]

Wow, 100 ppm, some orchid growers would kill to have water quality that good. Have read that Santa Barbera California has ppm levels as high as 1800 and 800 is not unusual in a lot of that state. I have 400 ppm in my part of Fla.
I like my pH to be 6.5 to 7 and deffinately would adjust any water as high as yours. The advise about fertilizer from Ray is great. It is good to know what is in you water - sometimes it is toxic to plants.

[Undergrounder]

Thanks again Ray and orchids3,

Looking at my fert there's nothing really missing in it that isn't in Ray's sheet so i think i'm OK for nutrients with my fert/sydney water mix. The only thing is i might have to watch the pH levels a bit more closely because i've possible been keeping them too alkaline. I know my fertiliser does acidify the mix down to about neutral but i haven't been keeping tabs on it.

Does P. violacea like a slightly acid environment? that would explain the yellowing perhaps.

[etex]

Great chart!! Thanks Ray!