Water Values (w/ Lab Results), What Makes A Good Water Supply?

So I sent the gap water I use for watering to a lab to see what my results are. Unfortunately at the same time, I don’t know what I am looking for in terms of best values for cannabis. Anyone care to impart some wisdom?

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Much of what is in tap water can actually be beneficial to the plant, including zinc, copper, boron, calcium, magnesium, etc… Some of them are harmful (chloride.) Chloride is easily mitigated by letting the water sit out for 24 hours to gas off the chloride.

The PPM of your water should be considered when feeding and PPM management. If your target of your input water for the plant is 1,000 and your tap PPM is 200, then your actual target PPM for feeding should be 1,200.


Two items I noticed was Sodium and Chlorine. Those of us with heart issues and high blood pressure watch for sodium. 20 mg/liter 20 parts per million is at the upper limit of what I think tap water levels to be Chlorine is not cannabis friendly. This is what CDC recommends for chlorine levels in drinking water


Chlorine levels up to 4 milligrams per liter (mg/L or 4 parts per million (ppm)) are considered safe in drinking waterexternal icon. At this level, harmful health effects are unlikely to occur.

I would be curious what your local water district reports shows for some of these values. The reports are often available on line.


I just pulled these from online. Looks like last years results.

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Another thing to pay attention to with tap water is the pH. FDA says a pH of 6.5-8.5 is acceptable. Ideally you want yours in the middle of that range. If pH is below that range that’s a sign that your tap water is polluted.

As long as your tap water is 300ppm or less it’s probably safe to water cannabis. Some sources say 300 EC (150ppm basically) is the cutoff, while others say 500ppm. This came up in another thread not long ago and it seems like 300 is the cutoff. With a TDS of 214 your water should be fine to water with. Like @MidwestGuy said you have to account for that in your nutrient solution ppm.

You can send a sample to JR Peter’s and they’ll give you a Jack’s 321 feed schedule based on your water. There is a fee involved and they no longer mail out collection kits.

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Cool, thanks guys!

Any advice on what you would add or slim down in your water/feedings based on these results?
I’m still trying to learn how to determine what I need to supplement with and how much….

I’d just keep everything in the same ratios as the feed chart for your nutrients suggests. That way you know you’re getting the right NPK at every stage. If you see any issues in your grow then start thinking about how to tweak things.

That’s the thing. I’m trying to keep things as organic as possible; using organic supplements. I don’t have any instructions as to how to formulate anything…

Trying to figure this whole thing out with research and questions.

That’s definitely outside my range of knowledge. I use salt nutes and haven’t looked into dry amendments much. I’d probably take a look at some organic grow journals or just start a thread asking what you need to grow organically. I know there are some excellent organic growers on this forum.

Yeah, I’ve been putting in many hours doing research on this forum.

Wish we had an organic sub topic so we’d not have to sort through all the other types of growing.

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I’d probably just find a brand of dry amendments I wanted to use and search it’s name on the forum.

Yep, been doing that :wink:

The purest form of dry organic amendments I can find around here is Down To Earth. Which I’ve already started to implement.

@RandomW201 i grow organic. Look at Elm Dirts line of products. Its 100% organic. I think i paid 80 bucks for 2 dry amendments and 1 bottle of plant juice and 1 bottle of bloom. Its derived from worm castings. If you are interested i have a cannabis feeding schedule they emailed me. Ive followed their schedule ( i implement 3 to 4 weeks into veg because the soil i use is good for 30 day ) amd i am very happy with the results thus far. I also use myco 2 to 3 times during the grow also. Heres a sunset sherbert currently 9 days into 12/12 using Elm Dirt.

I am trying out a product called highway dust and another called simply professional.

Cool, I’ll have to look into that company. That’s one I haven’t heard of.

I’m just trying to wing it and learn as I can on this first run. Trying to utilize as natural organic as I can. Maybe create an organic super soil after this run is over.

check out Volcanna Rain Water Conditioner, the easiest way to balance and remineralize your water without expensive Ro systems.

Volcanna Rain