Hello all.
Lot’s of rain here lately. I’m collecting in 65 gallon rain barrel. Straight off, it tests closer to 7 on pH scale. Question. If I bring down to around 6.5, will the water store at this level for let’s say one month?
Thanks in advance
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Might be worth waiting until you need it, or test a small sample to find out.
Good stuff, keep us posted on what you find.
99
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Just a little musing on my part, but likely your rain water is pretty close to distilled water. You said 7 pH, and I would assume low EC too. This is often called “soft” water. Without other minerals to buffer the pH, it will naturally drift back to 7 pH. Can I ask you why you want to lower the pH to 6.5?
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Damn @ReikoX you beat me to it again! @Sadiemei
If your running soils that ph level of 7 is just fine. If your running hydro you should be testing ph after mixing nutes and rainwater, but rainwater has natural “nutes” in it so easy does it. . .
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Im not sure about that 
Like @ReikoX said, rain water starts out as distilled water ‘vapor’. When it condenses into drops to form clouds, it sometimes condenses around particulates in the air - dirt, smog, etc. Those drops can then pick up additional particulates from the air, but again, thats usually SMOG type stuff or dirt.
I suppose you could consider dirt a nute, but I dont know how nutritious smog is
That however, will vary a lot depending on where you live. We have very little SMOG where I live and no dust storms - most of our air comes in from over the ocean, so it doesnt pick up much dust/dirt either.
Living in LA or some other major metro area would be different.
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@anon32470837
Rain contains nitrates—an important macro-nutrient. Rainwater contains nitrate – the most bio-available form of nitrogen. … Nitrates, which are made up of nitrogen and oxygen, are formulated by nature for maximum uptake by your plants. Plants typically absorb most of their nitrates from the soil.
Does this count as “nutes”?
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Sure. But, I’d guess you’d be looking at about <1PPM for some of the macro-nutrients. Which will come from the rainwater dissolving/absorbing whatever it hits. The roof, the ground, particulates, gases, etc.
Hey @anon32470837, here comes the PH and CO2 thing! 
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Then add in @anon32470837 “dirt theory” it’s like <3 ppm hahaha so. . . .
The old lady always said it’s not the PP-m
Its how you water it😉
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@ReikoX To get mid way as I’ve seen suggested (between 6 and 7). Reckon 7 is best?
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If you have a healthy soil, you dont have to worry about pH. It won’t hurt to adjust it, but I would wait until you water to do so.
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I wonder why it’s illegal to collect rain water in some states in America. Anyone know?
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@StevieG I found this site http://www.ncsl.org/research/environment-and-natural-resources/rainwater-harvesting.aspx
You’re correct. It does contain nitrates as well as sulfates, and phosphates - in many places, but not all. However, as @Northern_Loki suggested, the concentrations are so low I dont see how its anything to worry about.
The source is air pollution as I said above, which makes me ask what ELSE is in that water?
I found this rain water study.
https://people.carleton.edu/~bhaileab/environmentalgeology/RainWater.pdf
They found the following results from samples taken all across the country.
Chloride - We found that all 51 samples of rainwater contained chloride, ranging from .12 mg/L in Bloomington, IN to 4.21 mg/L in Kurtistown, HI
**Nitrate was found in all but 8 samples. Our largest concentration was found in Northport, Michigan with 8.16 mg/L. The smallest concentration identified was .13 mg/L in Lake Norden, SD **
Nitrite was only found in 5 of our samples.
**The largest concentration was .154 mg/L from Fair Banks, CA, **
Phosphate was found in 7 samples. Las Vegas, NV had the highest concentration of 1.14 mg/L.
Here is a graph of the distribution in the samples across the US. As you can see, a significant majority of the samples were under 1 PPM - most of those well under 1PPM and a large number with near zero nitrates.
On second thought, if your rain does have some of these higher concentrations of nitrates, then I would be far more concerned about acid rain or other pollutants in the water than a few PPM of nitrates.
I think this whole ‘rain water is full of nutes so its super good for your plants’ is at least partly an old wives tail Yes, it has nutes and yes its probably good for your plants - in many cases, but it does not have enough nutes so you can throw away your bottles just yet
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I use rain water myself out of my 300 gal sistern and no problems at all. Just pH after you put in your nutes.
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My guess would be so that the water company can continue giving it to you without lube…
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…Yes, Agenda 21.
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Basically the way I read it in response to that weedguys posting is that it all boils down to business and state water rights. My suggestion is if your going to harvest rain water in said states where it’s illeagle, treat it like your grow… Don’t tell anyone and hide the sistern.
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