I just had some rain last night so I stuck a 30 gal tub under the drain gutter. It’s full and i plan on using it. But should i give it to my indoor plants. Ppm of the rain water is 13. Ph is 8.8. Would have to ph it but is 13 ppm water ok for plants?
If anything I could still use it in my garden or make compost teas with. There is a lot of grit from the roof on the bottom of the tub.
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If yourppm is 13 then any ph reading your getting is not accurate as most people agree you need ppm at around 100 to get accurate ph. That being said your rainwater is ok to use anywhere.
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I’ve been using rainwater for a grow and going into my second with it now - it’s GREAT!!
As stated, Ph readings won’t be reliable - it’s almost like working with RO or distilled and will have to have at least CalMag added to get a reliable reading. On a side note - if you’re doing just straight water and no nutes you don’t have to worry about the Ph. It’s so pure it’ll just take on the Ph of the medium it’s being applied to.
Obviously if you’re flushing to adjust the Ph of the medium you’ll have to add CalMag to get enough charge into the water to have an effect on.
My rainwater comes in at 14.3PPM and 6.6 Ph, but it’s not a reliable reading.
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The rain water will be fine , once you add a little nutes or cal-mag to rain water on feed day you will have plenty of PPM to Adjust PH. Good luck
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Thanks for the quick replies peeps. I did add a little fish n guano liquid nutes to a gal of the rain water i was going to water a few vegging plants with. After that my ph dropped a bit ppm of the water is closer to 450 now. Thanks again. 
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You’re good to go , the more nutes added in the water will drive your ph down.
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ive been using rain water for my entire grow. see below. TL/DR its been good for me!
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What if im not planning on adding nutes to the rain water. How would you raise the ppm and adjust the ph then? I have flowering plants i need to water today but have already fed nutes too less then a week ago. I could just use the filtered water i have instead of the rain water i suppose.
straight rain water is probably fine. No need to PH.
If you must however, just add enoigh cal-mag to your rain water to get to about 100PPM, then ph adjust
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I used a lot of rainwater early on in my grow and never pH’d it and had no issues but I prefer tap water because rainwater had me using more nutes.
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I kinda do a hybrid honestly when mixing nutes. I use Jacks and generally will pour my rainwater into a 5g bucket save for a half gallon of hot water I’ll draw from the tap to mix in. Once I’ve got everything dissolved into the half gallon I’ll add my silica and Calmag to the bucket then pour in the nute mix, stir it up well and Ph it. After I get the Ph in the proper range I add my microbes and let it rip.
So I get a slight boost in PPM from that half gallon but not a lot which is why I’m adding Calmag with the nutes. I’ve got 2 BIG eaters going now and withut the Calmag they start to yellow between feeding because the eat so heavily. I also increased my Ca/Ni by a gram per gallon and they seem to be loving that. I have another strain going that was just fine without it.
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What kind of question is that 
?
Rain water 
? Okay 
!
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So how would you get the ppm’s up. My tap water is 24 ppm and 7.2 pH.
lol @yoshi, yeah sometimes you get too close to the problem, and need to take a step back to get some perspective. “Is rain water good for plants”? 
@GrnyGrows, adding cal mag or nutrient solutions to the water will raise the PPMs. If you don’t need either of those things, no correction is needed.
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A tsp per gallon of cal mag mixed first then veg nutes till the desired ppms
Awesome, thanks for helping. I’m so new, I’m still wrapped in plastic.
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Fresh water aquarium is just as good as rain water ?
@GrnyGrows I am very new so take this with a grain of salt but from what Ive gathered from all these nice folks here, having such low PPM, you will not get an acurate PH reading.
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I got good responses from folks I trust.
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I use rainwater and General Hydro Nutes.I used to use pots that utilized having water in each one, but now have gone to Jiffy potting mix and lava rock, with a single water reservoir feeding each pot.The mix has peat moss, coconut noir, and vermiculite. I stated seeds after germination, in the mix, and when 8” tall transplanted into the hydro pots. Plants are much bigger than any previous grows!
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