RO water and CalMag

Indoor Growing Hydroponics
#1

Hi OGers,

I have recently bought myself an RO filter because the water in my area is extremely hard. (0.65 EC).
I have never prepared nutrients with RO water before so i’m a real beginner in this area.
I am setting up a RDWC system eventually and am finding it hard to get info on the use of CalMag. (perhaps i am just not using the right keywords in my searches). I often see information about what ratios to use for specific CalMag products but I also often see comments like “You may not need to use any if using Hydro” and a lot of other contradicting info but not much mention of RO water.
My question is:
If I use RO water that is EC of 0 and I intend to use Nutrients like the Canna 2 part nutrients. What EC should I bring the water up to with CalMag as a starting point if I am using it in a DWC system before adding the nutrients? Or are there other factors involved?
Thanks.

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#2

I would add 1ml of cal/mag or litre of water on top of your base nutrient line up.

Then check see where it is at ec wise.

My mate runs DWC still and I run Coco now. He said his plants were slow growing and gave him the same suggestion his garden looked lush last time I saw it.

Peace

Bonged

#3

@Bongedtobits Thanks mate. Good to hear you have a story to back it up too. :slight_smile:
I will go with that to start with and see how we go. :+1:

1 Like
#4

@BudSy Nps matey. I’m sure other people can share there experience to help even more.

Just wants to share something I learnt from actual observation.

Check your PH after adding the cal/mag to the base as it may go up.

Peace

Bonged

1 Like
#5

You should always add cal mag to ro water first then your base nutes. Not doing so could cause fallout.

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#6

@SeymourGreen, thanks, I was intending to. I figured the calcium and magnesium would normally be in the water before I add my Nutes if I wasnt using RO water so would add CalMag first.

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#7

You hit the nail on the head :grin:

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#8

Yes,I alike to add my silica y chelators before the calmag, than any salt based nutes starting with the “micro” formula first.

Depending on many things (% of Cal and mag) but, you wanna go at least 100-150ppm min.

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#9

Exactly how I do it to! :+1:

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#10

I’ve been using it and I don’t have any problems yet, actually it was two of my friends who recommend me to use it!! The only issue is that probably you have to adjust the PH after adding the CalMag solution!!
In my case I’m using Canna products (AquaVega A-B) but CaliMagic from General Hydroponics with PH5.8 in the water!

IMG_20181124_101613_734.jpg1080×1920 462 KB

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#11

I’d add calmag until it reached an EC of around 0.4 then add the nutrients :thumbsup:

btw some folk mix their RO water with 50% tap water to bring the EC into the normal range but they might still have to add some calmag, especially in coco.

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#12

I too run ro, my tap water is over 400ppm.

I add 200ppm calmag and no worries

Currently running gh Flora series.

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#13

Thanks to all, I am feeling a lot more confident about how to use it now. I have a temp setup at the moment which i upped the EC by 0.4 with the CalMag about 3 days ago so that sounds in the ballpark of what you are all suggesting.

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#14

@Doulovebeef, wow! over 400ppm. I dont feel so alone anymore with my 0.6 EC.
From what I can tell the ppm scale that is used in this forum seems to be the one that is 500xEC. If that is the case then you have tap water with EC of 0.8!!!
That’s just nasty!

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#15

My city water is well over 750 ppm. We don’t even bathe in it, I spent a grip on a whole house ro system. It’s retarded. EPA won’t even approve our water for human consumption. …

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#16

I was sick off and on for a year, I switched to full house ro and my health improved, coincidence?

Since cannabis is an accumulator plant, I don’t want it accumulating that nastiness from my tap.

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#17

Wtf!?!? That’s just not right!

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#18

I have just been through a year long learning curve for RO and CalMag. I tried a few (Canna, Plant Magic etc) but could not find one that was as good as putting some tap water back in (always a Mg def) until I tried the Canna individual micronutrients. Even then I made the mistake of mixing them together in a holding tank and watching them combine into a nice particulate and drop out of solution.

I now put the Mag into a holding tank containing the nutrient part that has a little of that in (the clear part for Canna) and the Cal into the other (the brown one).

This means I am not stuck with the ratio in a bottle of CalMag, and I can avoid putting the extra N into my tank that seems to be an integral part of making CalMag.

It did puzzle me when my plants were dark green half way through flower when I was heavily restricting N…

5 Likes
#19

It’s rare for plants to be deficient in both Calcium and Magnesium at the same time so i can see your reasoning. I have to use the stuff but my tap water has virtually no Calcium or Magnesium to start with so i’m ok with a lowish dose.at around 0.6ml per litre of water. Everyone’s water is so different that what works in one place wont necessarily work in another.

New growers should try if possible to ask people in their location (who grow good weed) how they treat their water. Many potential problems could be avoided with this info.

2 Likes
#20

@Dr_Jekyll, @SeymourGreen, I second that!!! Crazy!