When diluting hard water with RO is extra magnesium via epsom salts typically required?

Hi all, greetings from rural Waterloo region, ON!

I live in a part of the province that feeds a lot of the rest of our province. There are farms and fields in every direction that as far as I know do just fine with the regions tap water.

But this being said – it’s extremely hard out here. Around 330 PPM from the tap currently.

I saw in another thread that target PPM for cannabis is somewhere around 100, so I use 10L RO to 5L Tap and this puts me right around 100-115PPM.

My question is this: without knowing the exact concentrations of calcium and magnesium in our tap water (I’ve checked the regions website, sadly they only test for heavy metals and lead), and knowing that we have extremely hard 330PPM tapwater diluted down to around 115PPM with RO, would supplementing additional magnesium be required with epsom salts?

I just picked some up after seeing conflicting forum posts online and am still unsure on this

Big thanks again for any advice, cheers!!

I would feed Epsom anyway, assuming that the product(s) you are currently using do not contain mag. You won’t hurt a plant with a little extra. I’ve never seen a magnesium excess.

What product(s) are you currently feeding?

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I’m with @MidwestGuy: Epsom is good for developing aroma.

Supplementing your water (nutes) is really going to be subject to what your medium is. If you are in coco you’ll want to add more C and Mg due to coco sequestering these elements. Many nutrient lines offer a hard water solution in their grow schedules.

I used to live in SoCal and the water was TERRIBLE! 550 to 600 ppm out of the tap. So yours is not so bad. I eventually went to straight R/O as I gravitated away from soil grows and more towards media grows like coco and Promix. Never had any issues, but you may want to run cal mag prophylactically.