Rainwater pH confusion

So. I have a few hundred L of filtered rainwater. It's all from the last few days, and I just checked the PH and TDS. It's pH 8.6 and 60ppm.

Everywhere I look, I'm told that rainwater has a pH of 5-5.5, and would benefit from dolomite in the potting mix to stop pH dropping if using rain water.

Asked a few ppl, and their rainwater also tests between 8.2-8.8, and between 50-70ppm. How come our rainwater results are so different from anything on google? I even checked out local councils testing, and it states that our recent rainfall was pH 5.6, and averages 5.5-5.8 over the last few months. .

VincenzioVonHook said:

So. I have a few hundred L of filtered rainwater. It's all from the last few days, and I just checked the PH and TDS. It's pH 8.6 and 60ppm.

Everywhere I look, I'm told that rainwater has a pH of 5-5.5, and would benefit from dolomite in the potting mix to stop pH dropping if using rain water.

Asked a few ppl, and their rainwater also tests between 8.2-8.8, and between 50-70ppm. How come our rainwater results are so different from anything on google? I even checked out local councils testing, and it states that our recent rainfall was pH 5.6, and averages 5.5-5.8 over the last few months. .

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Depending on the filter it can raise the ph.

Lordhooha said:

Depending on the filter it can raise the ph.

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I've tested three lots (fresh In buckets, from a cement tank, and filtered). It's always between 8.2 and 8.7. The rainwater in the cement tank is 8.7, the fresh rainwater is 8.2. When I mentioned "filtered", I meant "coffee filtered" just to get rid of big chunks, probably not needed, so I don't think it would change the pH much, if at all.

Either way, it is what it is, just interested as to why it's pretty much unanimous online that rainwater is quite acidic, but unanimous from everyone I know In real life thats it's alkaline...there's not usually such a contradicting swing In Information, so I thought this might be easily explained, and something that has just gone over my head.

For example, I've had a pool for years. Every time it rains for a while, the pool goes alkaline and algea forms, but when I talk to any pool shop they claim that Rian water will lower my pH considerably.

VincenzioVonHook said:

I've tested three lots (fresh In buckets, from a cement tank, and filtered). It's always between 8.2 and 8.7. The rainwater in the cement tank is 8.7, the fresh rainwater is 8.2.

Either way, it is what it is, just interested as to why it's pretty much unanimous online that rainwater is quite acidic, but unanimous from everyone I know In real life thats it's alkaline...there's not usually such a contradicting swing In Information, so I thought this might be easily explained, and something that has just gone over my head.

For example, I've had a pool for years. Every time it rains for a while, the pool goes alkaline and algea forms, but when I talk to any pool shop they claim that Rian water will lower my pH considerably.

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Perhaps it where you live then. Most rain falls in to the bracket of acidic. Even out in the country like I am.

You have a good calibrated meter? Use drops or litmus paper?

Lordhooha said:

You have a good calibrated meter? Use drops or litmus paper?

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I'm Gunna have to try papers one day. I've got three Meters, a Hanna groline, a bluelab pH and a cheapo from the aquarium shop. I just figured as they all read the same with a quick buffer test, that it should be fine.

I test rain/tank water every day - tests regularly at 8.1-9.8 PH and a EC 40( pretty much RO), only use Blue Lab PH and EC testers , when I add nutrients PH comes down to 6.0-6.3, EC depends on stage of grow

Scuzzman said:

I test rain/tank water every day - tests regularly at 8.1-9.8 PH and a EC 40( pretty much RO), only use Blue Lab PH and EC testers , when I add nutrients PH comes down to 6.0-6.3, EC depends on stage of grow

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Yep, I've noticed that the pH drops to around 6.5 once it's at 800ppm as well. Im not going crazy then. I thought I was living in an alternate universe lol.

Catch some of that rainwater in a plastic pail or something other than a cement tank as concrete is very alkaline and would also contribute to the ppm. Do you happen to live downwind of heavy industry that could be pumping nasty stuff into the air? Could be a long way away. All the acid rain that killed lakes in northeastern Canada comes from coal fired generating plants and other heavy industrial pollution in the eastern states.

The only way rain can be alkaline is if it picked up something from the atmosphere. It's always a little acidic at least from NOx and SOx emissions from burning fossil fuels that when combined with water form their respective dilute acids.

OldMedUser said:

Catch some of that rainwater in a plastic pail or something other than a cement tank as concrete is very alkaline and would also contribute to the ppm. Do you happen to live downwind of heavy industry that could be pumping nasty stuff into the air? Could be a long way away. All the acid rain that killed lakes in northeastern Canada comes from coal fired generating plants and other heavy industrial pollution in the eastern states.

The only way rain can be alkaline is if it picked up something from the atmosphere. It's always a little acidic at least from NOx and SOx emissions from burning fossil fuels that when combined with water form their respective dilute acids.

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I've tested plastic buckets of fresh, filtered bucket, and cement tank. It's strange. My city has pretty good air quality according to testing, and ranks pretty well. I know we have a bunch of limestone and calcium quarries around here, if that makes any difference.

I figured the stuff in the cement tank would be alkaline, but the fresh rainwater at 8.6 was news to me.

VincenzioVonHook said:

I've tested plastic buckets of fresh, filtered bucket, and cement tank. It's strange. My city has pretty good air quality according to testing, and ranks pretty well. I know we have a bunch of limestone and calcium quarries around here, if that makes any difference.

I figured the stuff in the cement tank would be alkaline, but the fresh rainwater at 8.6 was news to me.

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News to me too but if I had that I'd be tracking down the reason. Not normal. Just google 'ph of rainwater' and normal is from 5 - 5.8. Just the CO2 in clean air makes it mildly acidic. Doesn't take much to alter the pH of what is basically distilled water.

Sounds like a lot of chemtrail activity in your area maybe. Could be testing Bill Gates idea to spray powdered calcium carbonate into the atmosphere to radiate sunlight back out to help cool the planet. Won't need CalMag.

OldMedUser said:

Catch some of that rainwater in a plastic pail or something other than a cement tank as concrete is very alkaline and would also contribute to the ppm. Do you happen to live downwind of heavy industry that could be pumping nasty stuff into the air? Could be a long way away. All the acid rain that killed lakes in northeastern Canada comes from coal fired generating plants and other heavy industrial pollution in the eastern states.

The only way rain can be alkaline is if it picked up something from the atmosphere. It's always a little acidic at least from NOx and SOx emissions from burning fossil fuels that when combined with water form their respective dilute acids.

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Correct, listen right here. I collect in plastic and all my.rain water comes back with at 6.5ish.

Ive gone all tin foil now lol...especially when I leave a cup of distilled water beside it and the pH drops...I wanna get it tested now lol.....

All paranoid about strange amounts of alkaline oxides/hydroxides floating around now.

VincenzioVonHook said:

When I mentioned "filtered", I meant "coffee filtered" just to get rid of big chunks, probably not needed, so I don't think it would change the pH much, if at all.

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Big chunks of what?

There's little to no buffering in rain water. Low and unstable level of ions. It's very likely going alkaline from what was in it. Water in nature is rarely pure and it doesn't take much (impurities) to change an electrode reading in nearly pure water. 60 ppm, I wouldn't worry about it.

Of course this is just my opinion and further research on your part is always implied.

Flork said:

Big chunks of what?

There's little to no buffering in rain water. Low and unstable level of ions. It's very likely going alkaline from what was in it. Water in nature is rarely pure and it doesn't take much (impurities) to change an electrode reading in nearly pure water. 60 ppm, I wouldn't worry about it.

Of course this is just my opinion and further research on your part is always implied.

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The stuff from the tank has a few bits of leaf litter and what not. The freeing wasn't necessary anyway.. I just did it for the hell of it.

Funny when i check water make sure the temp is between 22 & 26 That’s water temp in Lake Victoria Kenya , rain water should give you 6.3/7.1 depending on where you live in the world . Maybe thats just me , i Think one should measure Ph at the temperature you want to use the water or whatever,

Kayaganja said:

Funny when i check water make sure the temp is between 22 & 26 That’s water temp in Lake Victoria Kenya , rain water should give you 6.3/7.1 depending on where you live in the world . Maybe thats just me , i Think one should measure Ph at the temperature you want to use the water or whatever,

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Most pH pens have built in temperature compensation so you don't need a perfect temp to get a fairly precise reading. Not sure about the cheap Chinese $20 units you get on eBay and Amazon but I don't buy those.