Water gurus - cal/mag question

I have never added Cal/mag to my water but I see it’s something a LOT of people are doing here…

If my plants are not showing a cal/mag deficiency should I be adding it anyway?

I water with untreated ground well water.

I’m usually of the mindset of not adding stuff unless the plant says it needs it, just seems like a lot of folks add it regardless.


You would be hard pressed to push your plant into Calcium or Magnesium toxicity, adding
a cal/mag wouldn’t hurt.

On the other hand, your plants are getting all the calcium and magnesium they need so
why mess with perfection.

You could add gypsum, egg shell meal or a series of other soil amendments to bolster the
mineral content of your soil in the off season so you can continue to grow as normal.

You are in a unique position here because you can do either and still be ok.


I got a water test last year and here’s what it said if that is any insight

1 Like

Oh. Well that explains it really clearly I guess. My raw water is basically a cal/mag supplement

Hardness of 25 is fricken Harrrrd.

I never knew what makes hard water “hard” until today.

From the USGS:
“ In scientific terms, water hardness is generally the amount of dissolved calcium and magnesium in water”

So no. I don’t need cal/mag it would seem!


My tap water is around 200ppm. I don’t know if that’s hard or not but I still have to supplement cal mag

1 Like

If it ain’t broke dont fix it. Imo. I wouldn’t hit em with calmg last u knew u needed it.

Greetings all a very new guy here. I got my meters in yesterday and played with them and here are my results for you water experts. My question is would you work with my tap water or should I start with distilled water? Results below.

Distilled on hand from store
Which would you all suggest? I was just going to go with distilled and add FOX FARM NUTRIENTS to meet the spec’s for the weekly feeding guide for FOX FARM OCEAN SOIL, in which I intended to use.
Thank you for your time!

Is that tap water municipal or well water?

1 Like

Hopefully well are city water is full of chlorine and chloramine, but then again the way are earth is being polluted.

I’ve grown with municipal tap water before. It’s … less than optimal :roll_eyes:

1 Like

Thank you for your reply and time! The water is municipal on the weekends it reeks of choline. I used to have aquariums and had several fish spawn, good after I removed it, so decisions, decisions.

1 Like

I would ask for the annual water test report from the town before you decide. Good to know what’s in it and how they’re treating it. If they are softening it that’s gonna make it less than optimal for your plants due to the salt

1 Like

Thank you for your reply, I am going to get that information from the county. Thanks for the idea.
Thank you

1 Like

Here is my findings, hope this is the information you were talking about?
Thank you
Contaminant Date
Tested Unit
MCLG 90th
Above AL
Major Sources Violation
Copper 2019 ppm 1.3 1.3 0.1 None1 Corrosion of household plumbing
systems. NO
Lead 2019 ppb 15 0 ND None1 Corrosion of household plumbing
systems. NO
Contaminant Date
Tested Unit MCL MCLG Detected
Level Range Major Sources Violation
Barium 2020 ppm 2 2 0.045 (0.02-0.04)6 Discharge of drilling wastes;
Discharge from metal refineries;
Erosion of natural deposits
Chloramines 2020
MRDL = 4
As Cl2
= 4
As CL2
3.14 (1.0 – 4.5)6 Water additive used to control
microbes NO
Fluoride 2020 ppm 4 4 0.75 (0.6 – 0.7)6 Erosion of natural deposits; Water
additive for strong teeth. NO
Nitrate+Nitrite as N 2020 ppm 10 10 0.35 (0.1 - 0.3)6 Runoff from fertilizer use: Leaching
from septic tanks: Erosion of natural
Radioactive Contaminants
Combined Radium 2020 pCi/L 5 0 0.2 N/A Erosion of natural deposits NO
Microbiological Contaminants
Total Organic Carbon
(TOC) 2020 RR TT N/A 1.12 (1.0 to 2.4)2 Naturally present in the environment NO
Turbidity 2020 NTU
TT, < or = N/A Soil runoff NO
0.3 NTU
(95% of the time)
Volatile Organic Contaminants
2020 ppb 80 N/A 514 (14 - 102)6 By-product from drinking water
chlorination. NO
(Haloacetic Acids) 2020 ppb 60 N/A 434 (ND - 120)6 By-product from drinking water
Non Regulated Contaminants
Sodium 2020 ppm N/A N/A 307 (12 - 30)6 Erosion of natural deposits NO


I would not give it to my
Plants nor do I give it to my cats. Your water report is about the same as my city water. I either get pure store bought spring water, or where I live we have reverse osmosis water you can buy cheap at the grocery stores.
I seen chloramine in that report. I read That can only be filtered out or as hell raiser said condition out Or invest in a RO unit.
If I give them pure to water or distilled water I always add a little kelp

If my tap water was 138ppm, I would use it, but the chloramines need to neutralized, can use a water conditioner for that, like Stress Coat made for fish aquariums.

1 Like

Thank you for your reply and time! I am very happy for your advise and it will be put into action tomorrow., heading to the grocery store. I use distilled water for my c pap and always have three gallons around, so will that be fine?
Thank you both for your great help!

Thank you Hellraiser for your time! You are correct in the fact of stress coat or treatment for the levels listed, and it out of control on Thursday thru Monday. I had aquariums for years and was very successful with this water even in breeding, but treatment was very important.
Thank you for your time

1 Like

Greetings all, and thank you for your time and replies. I am hoping this photo up loaded ok never tried in this on this site. What the pic shows a way of flushing plants into a clothes washer catch pan. I built a 2x4 frame to lift it up for drainage and to clear the zip door on my tent. All that has to be done is attach a garden hose to the fitting that I drilled and threaded for. I heard several people ask about flushing and having a wire SOG in place and not to be able get rid of run off in side the tent, so I am hoping that this will help me as well. Pan size 30x32 perfect for my 4 5gal. Containers.


Nice, that’ll make runoff easier to deal with.

1 Like