Distilled Water - Calmag?

Hello friends!

I’ve been using store bought distilled water to get my seedlings going in order to ensure no issues with local water and plan on switching them over to tap water once they are happily transplanted into their final homes (5 gallon felt).

I have read in a few places that distilled and reverse osmosis water use requires the addition of calmag, is this true? If so, why is it?

Any info and education on this topic is greatly appreciated.

Thanks in advance!

Yes, that’s true, you need to add Cal Mag because distilled, or RO water contains nothing, so you need to add everything into it. People do this so they know exactly what is in their water, only what you put into it.


What he said ^^^

The cal-mag directions even have a dilution specific to seedlings.


What she said! If your TDS is above about 250 ppm it may not be necessary to add cal mag, depending.


What they said! Seriously though, @SmoknGranny found an article about Cal-mag (I think produced with the assistance of them) stating that needing their product is very rare if you use tap water. One of the specific reasons people need it is using filtered water that has those micro-nutrients removed. Another is weed growers in flower, that notice a specific deficiency.

My chlorine (or chloramine, or whatever) was high in my tap water, even after filling the bucket with a sprayer to aid in aeration and sitting it out for 48 hours. I use a zero-filter and it removes pretty much everything, then I add cal-mag every other watering with the other nutes.

I did my last one-plant grow with a zero-filter, and one cartridge was sufficient for the grow. By the time the filter starts losing its efficacy, the plant is old enough to not care. So for $10-15/plant, you know exactly what is in your water.


Thank you to everyone here for the educational info and for the response. Loving the community here so far! So glad I signed up :slight_smile:


Ive been buying Gerber water for babies at WalMart. $1.28 a gallon compared to .84 cents for distilled water. The Gerber water is labeled as all minerals included. I figure if its good enough for babies its good enough for my ladies as well.


I think there’s probably stuff in there (like sodium) that really isn’t a good idea for plants. You’d be better off with the distilled and some cal mag.

Here’s that article


The water analysis report of Gerber water has very little sodium and it does have Calcium and Magnesium. I am just not sure the amounts of the cal and mag are correct.

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