# Do I need to use Cal/Mag?



## Chen (Nov 27, 2016)

I've not seen any Magnesium or Calcium deficiency but everyone seems to think Cal/Mag is a necessity.

My hard tap water is ~350 PPM. My soft r/o water is ~50 PPM.

If I use hard water, do I still need Cal/Mag.. or do I need less of it?

How do I figure this out?


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## lyfespan (Nov 27, 2016)

Chen said:


> I've not seen any Magnesium or Calcium deficiency but everyone seems to think Cal/Mag is a necessity.
> 
> My hard tap water is ~350 PPM. My soft r/o water is ~50 PPM.
> 
> ...



look up your cities water testing results. RO should be 0ppm btw. please dont be using soft water.

those redish purplish stems are a sign of MG def, easily fixed with epsom foliar at 1tsp per gallon, bring ph up to 5,5 with silica. dont foliar buds after 4 weeks, or risk rot


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## The Hemp Goddess (Nov 27, 2016)

There is a big difference between softened water and RO water.  Like lyfespan said, you do noy want to use softened water to water your plants.  If you are using water that is softened, it could be why you are having problems.  Not all RO water will come out at 0 ppm though.  If you have a lot of dissolved soids in your water, the best an RO may do is 50 ppm...which is just fine.


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## Chen (Nov 28, 2016)

Well, I bought a Reverse Osmosis filter because R/O water is essentially better, right? You take out 300 PPM of crap and use more nutrients.

So, the question is - if I'm using 50 PPM R/O water, should I add calcium or magnesium, and if so how much?

With nutrients you can sort of tell by the PPM, but you can't know how much Cal/Mag is in the mix or how much needs to be without a feeding schedule.. and there are no specific R/O water feeding schedules that include Cal/Mag supplements.

In fact, I can barely find any at all. I've been using Epsom Salt for a few years now, every few months when the leaves get yellow.


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## pcduck (Nov 28, 2016)

With ro I always use cal/mag. 10 drops per gallon.


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## zem (Nov 28, 2016)

lyfespan said:


> look up your cities water testing results. RO should be 0ppm btw. please dont be using soft water.
> 
> those redish purplish stems are a sign of MG def, easily fixed with epsom foliar at 1tsp per gallon, bring ph up to 5,5 with silica. dont foliar buds after 4 weeks, or risk rot



i always linked the purple to phosphorus deficiency, mg deficiency shows up as interveinal  chlorosis and curled up edges ime


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## trillions of atoms (Nov 28, 2016)

What kind of r/o is it?


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## The Poet (Nov 29, 2016)

What's RO ?


                    Poet...


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## zem (Nov 29, 2016)

The Poet said:


> What's RO ?
> 
> 
> Poet...



reverse osmosis


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## grass hopper (Dec 1, 2016)

calmag fan..


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## Hushpuppy (Dec 3, 2016)

If you have been using Epsom salt with success then you will need to continue to use it. Measuring will depend on your medium type and size for each plant. If you are using coco based medium then you will need a little more Epsom, with "most" organic soils, you will not need as much. If you are purely hydro and use synthetic nutes then you will definitely need to add Epsom salt and possibly a little calcium. You will have to experiment with it a little to find out how much they need to stay lush. 

If after switching to RO water, you see the leaves suddenly begin to fold like taco shells or begin to get lighter around the edges of the leaves, or get little spots, both semi uniformly across the plants, then you need to increase the magnesium for the taco/edge discoloration and calcium for the little spots.


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