Well water and calmag

My well water is 6.5ph and 15ppm out of the tap. Does this mean I should use calmag every feeding, watering, both or none at all? Thanks for any advice.

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You will need calmag to properly pH the water. So yes, except for flushes. With ppms so low the water will just take on the pH of the soil otherwise. And any readings of pH are potentially false. If you’re using a cheap pH meter, wiggle it around and watch it bounce while it fails to register. This is why a lot people don’t think they work. Generally well water isn’t that clean though. Double tank + brine tank set up? House filter? Curious because I have everything for my house upgrade except the brine tank, current set up rented from culligan, junk. 350 ppm on a good day.

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I have the yellow tester from Amazon and I have a Apera ph20. My well water just happens to be that clean, I don’t have a filter or any kind of purification system. @Budz

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Lucky. But yeah if your ppms are that low, an easy way to test against your ppm meter. The yellow should bounce around when shook in the water. If it doesn’t, your ppm meter isn’t working correctly. As a general rule you want 100ppm minimum to be able to set the ph.

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The yellow one does bounce from 6.8 to 6.3. @Budz

Good. So yes. I zero filter my water. I add calmag for every watering and feeding except on my seedlings and fresh transplants. Since I use happy frog I know it has what it needs at that point, and since my water has 0ppm I know it’ll take on the pH of my medium, which is already buffered to 6.3 if I remember correctly. Then if you do two week flush at the end that’s usually just di/ro/0 water straight too.

Thanks so much, that helps a lot. So when my runoff drops below 800ppm I should start feeding and how much calmag do you add to a gallon? @Budz

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I use 1.5ml of mine with feed. I see it as adding back the essentials I removed from the water, not using it at a nutrient in and of itself. Some nutrients even make lines for use in distilled water, in which case you wouldn’t use any calmag. I’m not sure the differences in calmags either. They all say 2-0-0 but there are always varriances. Tolerances n such. I use.


And that’s 1.5 in flower. It calls for 3-5. Which brings it up to around 250ppm. So I could probably get away with less.

If you want to know what people use specific to your nutrient line, I’m sure we could point you in the direction of someone who uses or has used the same nutrients as you do. For a more specific answer. I may even have it sitting around. Like if you’re growing hydro with GH nutes. I gots that already, was for someone asking how to use the trio/order.

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I draw my water from a 200’ well in a limestone aquifer. My ppm is 150+_ with ph 7+. I imagine you will have to supplement for the lack of calcium and magnesium in your water. The amount and frequency will depend in part how much is supplied by your nutrients. When I used fox farm nutrients I would always have to supplement. With advanced nutrients in soil, significantly less. Now growing in coco and using Jack’s 321 - back to adding CalMag.
When I use rain water I collect, its ppm is like yours. Virtually zero.

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Welcome ! I like to use Cal Mag on water day only. That’s just me , good luck

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Thank all of you for this info, it’s really helped a lot. Y’all have a great day :relaxed:

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