From a fellow grower: I am having a very difficult time balancing PPM and EC. When I add just a small amount of seedling fertilizer to the water, the EC shoots up substantial above your nutrient guidelines, per Bergman’s Hydro Feeding Schedule. For example, with a ppm of 350, I am getting an EC of 630. How do you suggest I handle this? Which of the two measures is the more important one to manage to?
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Ppms tell how many parts per million are in the mix and ec tells hiw much nutes the plants eat out of that mix. If not using distilled or ro water u have to add in the ppm numbers for the tap water which will throw off all the numbers bergman gave on his chart. Yheir charts go by ro water or distilled water which have super little to no ppms. @Dman1969 @CMichGrower @Oldguy @Happilyretired may e can leave a better reply to break down more on this or tag a family growmie to help.
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Thanks for the tag @Mark0427
Here’s a chart with the correlation between the different scales for total dissolved solids in your mixes.
Ec is the first column.
Looks like you forgot to move your decimal point 3 places to the left
The 630 reading should actually be .63 ec.
That = 300 ish ppm on the scale chart.
So both of your reading cross over to each other on the appropriate scale.
EC readings are converted to get the other numbers on the scale.
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@Oldguy some ya got brains some ya got braun. Put them together u get awesome weed growers lol. Im not awesome yet but working on it.
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All good @Mark0427 
It doesn’t happen overnight my friend. 
So long as you learn a bit more each grow then that’s progress.
I still learn something new about this wounderous plant every day.
Love it. Love it. 
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Me too my wife got the demon staryed in me getting me going with 3 seeds at the start of the covid lockdown here in michigan. Now she cant pull me away from it i love it it is fun relaxing and the reward at the end it just marvelous
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TDS PPM and EC are basically all the same thing. TDS and PPM are a measure dissolved salts / minerals. The difference between the two is which salt is being used to obtain the reading. But meters we use aren’t actually measuring TDS or PPM it is actually measuring electrical conductivity EC and then uses a formula (conversion factor) to display the amount of dissolved stuff in the water
So the disparity of the your numbers is what do the numbers represent and what scale is being used.
More than likely it is like @Oldguy says.
630/1000X500 = 315 - just ending up with a wacky conversion.
If interested this is an article that does a much better job of explaining this stuff than I do. Can’t do a direct link
trees ^ . ^com/gardening-and-landscaping/tds-ec-ppm
More than likely you need to change the MODE, that is the scale, your meter is displaying. Choose the mode / scale that is used by the nutrient line.
Way back when I put this conversion table together when I used fox farm nutrients and it used a 700 scale.
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That’s actually .63 which is around 350 ppm. You are reading the same thing but reporting different types of output. Use one or the other…
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