Electro conductivity measurements

I am not very technically literate . . . I posted a question yesterday but I can’t find where I posted it or any of the replies. My apologies for this. Hopefully I’ll be able to find this post and the answers. lol

I’m using Oneness for my fertilizer. I used to grow years ago and always tested PH and PPM of electo conductivity. Does anyone know of a good resource for information on what the PPM should be at the various stages of gowth? The instructions on the Oneness container indicate the amounts of fertilizer used varies depending on the stage of growth but doesn’t indicate how to measure the water (PPM). I assume I’d need to know what the ppm should be when there is a variance of how much fertilizer is to be used (see all the stages below except cuttings/seedlings).

Any help is greatly appreciated.

Cuttings/Seedlings: 1ML/gallon

Vegetative Stage (Week 1-2): 3-5 mL/gallon

Flowering (Early/Transition stage Week 1-3): 5-10 mL/gallon

Full Bloom (Fruiting stage Week 4-8): 10-15 mL/gallon

Flush Stage (5-10 days): NONE

Never heard of the nutrient line you are using.

Some supplements can be run at full strength, seedling to harvest (look up Jack’s) and others list the TDS for different stages of plant growth (General Hydroponics, Fox Farms etc).

Depending on your grow medium choose a chart.



Ingredients per gallon.



From the page you are on right now, click your G icon in upper right corner.
Then click on the bell (left 3rd icon)
that will take you to your summary page

This is what mine looks like / yours S/b the same

Click on activity and a list drops down
The list of activities includes the Topics you created and Replies you have posted.

Hope this helps.

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@Glaadiss Here you go. Click on the link. Its your profile. You can see your posts by clicking on it and same with your topics. :+1::+1::+1:

Your info

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Thanks for your reply and the chart. Those values are per gallon - correct (Week 1 - 2ml per gallon water)?

I grew 10 years ago and always checked ppm of electro conductivity. Is it unnecessary to check this any longer?

@Glaadiss You can check PPM of the water and nutrients with the right meter. Like for pH I have a Apera 20.

I have a TDS meter for PPM. Nothing fancy but it gets the job done. I have several meters for the PPM so with my Feeding chart its pretty spot on for what Fox Farm states. Since I use their products.

Thanks MrPeat. I’ve got the meters PH and a seperate one that checks EC. The question is what PPM of EC should I be aiming for at the various stages of growth.

The charts talks about how many ml of nutrient to use per gallon of water, but doesn’t provide any information on what the PPM of EC reading should be.

For example:
Cuttings/Seedlings PPM of EC should be what?
Vegetative stage PPM of EC should be what?
Full Bloom?

I’ve tried contacting the company but get no response from them.

Yep, they also include additional supplements from the Humboldt nutrient line. I have been using General Hydroponics Flora Series line. I couldn’t find a grow chart that included ppm recommendations. I believe most nutrient lines are close to the same but don’t hold me to it. Check with your supplier for grow chart complete with ppm.
Also if your using hydroponics you really need to include the additional supplement’s listed.
Here is one from GH.

Here’s a link to the companies website where they have posted feeding charts


I start out using the manufacturer’s guidelines and tweek my nute use throughout my grows. I aim for between 800 and 1200 PPM, and aim for my pH to be between 5.8 and 6.2. I’ve been doing this 10+ years and have never been disappointed with my results. Keeping a journal helps me track my nute use and over time I can see how different products mix and behave. Good luck.


I use Fox Farm nutrients so I can say this. Most growers use PPM and not EC. FF feeding chart gives the EC and PPM scale. So they cover both so if a grower wants to use EC, they can know the numbers and vice versa for PPM. I don’t use EC so no idea how it works.

EC and PPM are both different ways of expressing a solution concentration:

EC of 1 equals 500 ppm (NACL scale…USA)
EC of 1 equals 700 ppm (Imperial scale…UK and Canada)


@Myfriendis410 Thanks for explanation. I understand that it was a different way to measure. Just not the detail you gave. Appreciate it. :+1::+1::+1:

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