Do I need cal/mag if watering with hard well water?

Was told i had hard well water years ago and did a quick google search that claims hard water usually has high levels of both calcium and magnesium. Should i get this checked before purchasing a cal/mag product? Is it ok to water with higher levels of cal/mag on a regular basis?


Welcome to the community @NCStealthGrowr

I used calmag just small bottle, i will recommended just cuz you never know went you plants going to ask for more calmag

Happy growing :green_heart::metal:


like @Mefis stated the plants will let you know. here is a guide to nute deficiency.


It depends a lot on the nutrients you use too. With Jack’s for example it isn’t usually needed. You can modify the ratio of the 3 parts to up cal & mag. If you are using fox farm trio, order calimagic. you will need it sometime. I have fairly hard well water and had to add calmag when I used the trio.


i started adding it to mine on the FF trio about 7 weeks in.

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I’m going to order a bottle to have on hand. If my well water naturally has high levels out the ground tho, will it harm my plants i guess is my biggest concern. I didn’t see it listed on chart, so is it safe to assume i’m good to continue using my well water? Or hard water period. Water is full of minerals. Hot side is like slowly sandblasting at metal fittings in plumbing, its so bad. i got 10 years out of original before they started blowing out


So im reading high mineral, hard well water in general can potentially cause nutrient lockout. It said high levels of cal/mag will do the same. Is this when a flush is needed? Should i get a 2gl capacity brita and filter, then add cal/mag supplement in as needed?

do you have a PH meter? im curious what your PH reading is on your water. what medium will you be growing in and what nutes will be used?

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yeah, mid 5’s i think it was. In COM stonington. Have the FF trio on hand. Wanted something simple for first grow

ph of 5? when you mix the nutes based on my water it drops my ph level.

yeah, that’s low right? I’ve only really watered good once, but i had to add a decent amount of ph up to get around 6.5

@beardless what was your ph on your water before nutes? BRB gotta charge my phone.

Base PH of water is 7.5 - 7.8. I have a softener so my ppm will approach 200.
@NCStealthGrowr do you have a ppm pen. What are your readings? plain tap water PH PPM


i got the cheap ph meter pen and tds meter pen duo from vivosun when i ordered the tent. I haven’t used the tds/ec meter yet. let me go check real quick

Ph 5.8 PPM 75

now i see why you need PH up

@noddykitty1 really knows his stuff about water and pH. Could you offer any advice here my friend?

Probably not but good idea to have some on hand just incase

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That’s the numbers of the well water?
If so its not hard. Thats very soft water and will need full strength calmag


Yep. Hard water causes stains along with many issues in plumbing and appliances fed by it. I get horrible iron build up in toilets/showers, even with inline water filter. Have been told by different companies that my water is hard from all the mineral, and only solution was a water softener system. You can taste the metal from it in the water. It may not have calcium or magnesium, as it seems what the rainwater filters through as it goes down, determines what minerals are in it. Limestone and something else in the ground caused higher levels are cal/mag i think i read. I’ll order some cal/mag to have handy and keep an eye on the leaves