pH of water used on plants

[ChasWG]

So I was searching the forums to see what pH the water should be for my orchids, but didn't see much. It seems to me that these plants would want a more nutral to acidic balance. And of course the tap water in my area is very hard. High quality, but hard.

Should I be treating the water to lower the pH and if so with what? I know the plants don't like all the chemicals we put into tap water, so what should I do or be watering with?

Thanks

[camille1585]

The pH is not necessarily important for the plant, but for the assimilation of the nutriments in fertilizer. The optimal pH for maximal assimilation of all the nutrients is around 6.5, with a range of 5.5 to 7.5 which is fine. If you have a very alkaline pH, like 8 and above for example, Potassium, Bore and Iron are not as assimilable.

You mention that you want to lower the pH because the water is hard, but water hardness is completely different from pH. Hardness is a measure of the quantity of calcium and magnesium in your water, while pH measures acidity. The two are not necessarily linked. Hard water is naturally morelikely to a high pH, because it is also high in carbonates that buffer the pH toward the alkaline side.
You would need to test the pH of your water to know. Hard water is not a problem for plants, so if your pH is within normal range, you're fine.

[ChasWG]

Thanks for the chemistry leason! Yes the water here is hard and alkaline. The pH is around 7.2 to 7.5
But beyond the acidity or akalinity, what about the other things we put into drinking water like chlorine and chloromines? I know for sure those don't happen in rain water.

I have read that some folks use filtered tap water. Is bottled water suitable?

[Des]

I also aerate my water using an aquarium aerator, the disolved O2 in the water displaces the CL2 in the tap water making it a little more like freshly fallen rainwater. I also sterilize and oxygenate the water using Hydrogen Peroxide.Whenever I use H2O2 on my Cymbidium seedlings I can almost see the growth spurt.
There is no doubt that if the ph of the media within the pot (if you are growing Cymbidiums ) is too high that the plants will starve in the midst of plenty as they they are not able to take up important nutrients . I suspect that nitrogen uptake is also affected to some degree. This is one of the reasons why folks end up with a pot full of back-bulbs . Get the PH and nutrient levels right and the plants will have far fewer back-bulbs. The plant will then grow and flower for you like never before !!

[Ray]

Clorine is not stable in solution in water. letting is stand for 24 hours usually gets rid of most of it. Des' suggestion of aeration is an accelerator to the process by increasing the surface area, not really by substituting oxygen, as that would be an extremely transient effect.

Chloramines, on the other hand, don't go nowhere, and are not a good thing.

What Camille indirectly brought up is the alkalinity of the water - it's ability to withstand pH change by acids - is quite important, and is actually a stronger player than pH alone. If you have a head for it, and really want to learn more about all of this go to my website and read Dr. Bill Argo's 5-part series on Plant Nutrition

Some folks rely on relatively inexpensive RO systems to produce pure water for irrigation, as that allows them to control the chemistry quite precisely. Yeah, there's an initial investment, but on a per-gallon basis, it's cheaper than anything besides collected rainwater.

[ChasWG]

Thanks for all the help guys and gals! As far as an enthusists web site, this place ROCKS!!!
I belong to several different types of web communities and none so far hold a candle to the helpfulness and friendliness that this community has shown me and others here so far.

A huge THANK YOU!

ps, I just got back from trying to visit my favorite garden center. I wasn't going to do anything orchid related, but as my wife and I turned intothe driveway for the store, there hanging out front was a huge welcome banner for the local orchid society. They closed at 5pm so I did't make it into the store, but it's a 2 day event and Tagawa's so I'm back there for sure on Sunday!!!!!!!

[brush]

Where I live they really like to treat the water with alot of chlorine and it seems to be a lot stronger smelling at the beginning of the month . When I fill my containers of water , I will let them sit for 24 hours before using them on my orchids . Seems they don't favor the chlorine at all.