RO water..

[rama777]

I don’t know what’s in my well water but I start thousands of lettuce plants every year indoors and I know they hate it. So I use rain water but I just installed RO for my winter tent grow because I have to decommission my rain harvesting setup due to the freezing temps.

I’ve spent a ton of time pouring through stuff but it’s conflicting!!

I got some roots organics calmag (no nitrogen) and was going to just add about a teaspoon per gallon at all times. Or? I don’t know!

As opposed to just adding a teaspoon, would it be better to hit a target ppm? What would that ppm be? Should I use that same ppm before adding nutes as well as when I’m just doing a water only watering? Any advice? I feel like I need at least something before getting a workable base to ph my water first.

So far after my first test adding a teaspoon of calmag to my RO water I’m getting a reading of 7.0

Before adding calmag it was claiming 8.5 or something. I use drops in a vial, not a pen. I understand you shouldn’t stick a ph pen in RO water. I don’t have one anyhow.

Other option is to add back some of my well water to get a base target ppm. And again, what is the base target and is it always the same, with or without nutes? But, I’m not going to do that until I get my well water tested first. I can’t do that for a while so just seeing how to dial it all in. Thank you!

[mrgrowit]

Yup 1 tsp matches the dosage it mentions on the back of the bottle for the stage/size of your plants (assuming they are the same plants from your other post). Here’s what it says:

Roots Organic CalMag
“Seedlings and small plants
Use 1 teaspoon (5ml) per gallon
Mature vegetative plants
Use 1-3 teaspoons (5-15ml) per gallon
Mature flowering plants
Use 2-3 teaspoons (5-15ml) per gallon”

Many growers will give CalMag every watering while they give their regular fertilizer every-other watering. However, there are many ways to go about it. How do you plan to use the fertilizer? Yes adding nutrients then pH after. In soil, many strive for 6.5 pH while the general range is 6.0-7.0pH. Some growers go outside that range and their plants turn out fine though. So this is something you really don’t have to be 100% precise on IMO.

I believe I touched upon all of your questions but let me know if I missed anything.

[rama777]

<p style=”text-align: left;”>I pH’d it down to 6.5 with phosphoric acid. The company that I got my soil and nutrients said anywhere between 5.8 and 7 will be fine. Pretty easy there. I’m just gonna by their guidelines, which is to feed twice weekly. According to them, I should start feeding now. I’m hesitant about that so far. I haven’t used any yet. Once they go into 7 gallons, I’ll consult with them again about wether or not to keep feeding (if I start by then), or to back off since the roots will be finding fresh nutrients for a while. Take a look at what’s in my veg nutes and see if you see any good reason to start feeding now. If these are all things that need microbiology to effectively break down to become available, I could see why starting now might make sense. If there’s nothing that will be relatively quick release, then I assume it would be better to start now then wait until a potential deficiency arises.</p>
 

 

[rama777]

And here’s what’s in my soil, also from the same company. The only thing that strikes me as readily available is the blood meal and guano.

[rama777]

I bit the bullet and did a half strength feed last night. We’ll see how it goes. If it turns out to be detrimental, would I see symptoms within 2-3 days?

[mrgrowit]

Yes 2-4 days you may see burnt tips or leaves become much darker and/or shiny if it ends up being a problem.

[rama777]

For simplicity’ sake I’m going to continue putting in calmag with all my waterings. My strain is supposedly calmag hungry, whatever that means. Giving more details about ppm/ec would be nice but we’ll just have to go with “calmag hungry.” I was just mixing up some water and had a hunch that the EC with my calmag would be higher than I  was initially assuming. The bottle recommends 2-3 teaspoons per gallon in mature veg, which is where I’m at. I put 2.25 teaspoons into a gallon and sure enough the ppm was a bit over 400! That doesn’t leave me with as much overhead as I’d like for my nutrients. So, while I know you can’t tell me the exact perfect amount to use, does your experience give you an estimate of what a good target ppm might be for an allegedly calmag hungry plant that is going to be getting it with every watering (until much later maybe..) using RO? 100ppm with every watering, 200, 250, 400!?

Or, would you recommend doing medium to high doses of calmag and RO water only in between feedings so that I can be hitting them with full strength nutrients in between calmag only waterings?

Both are viable options I know. I’m leaning towards calmag with every watering though, and would be psyched to have someone just recommend me what ppm to roll with for every single water preparation I make. The plants aren’t super heavy feeders I don’t believe, so I think I’ll be okay to lose some overhead to the calmag. But, 400+ with every watering seems potentially excessive.

[rama777]

Also I suppose I’ve watered in the transplants with 400ppm of calmag, plus watered two of the plants with another 400ppm of calmag. If that sounds like dangerous territory, perhaps I should give those plants zero calmag for a watering or two, or three?

 

[rama777]

Oh worth mentioning for sure is that my nutes have calcium and magnesium both. The people who make it told me that some strains still need supplemental calmag though. So whatever we pick as my target ppm for all waterings should certainly take that into consideration.

[mrgrowit]

Sorry for the delayed response as the past few weeks has been hectic. I can’t recall what the PPM is of just one full dose of CalMag in 1 gallon of water. If I had to guess, I’d say it’s around 250, and can vary depending on the brand. Some growers feed CalMag every watering while others do it only between feedings of base nutrients. Yes, if you “read the plants” and think they could do with a water-only once or twice, go for it. I personally do this once I see the leaves on the verge of becoming too dark.

[rama777]

Oh that’s interesting. So calmag can deepen colors in a similar fashion as potentially excessive nitrogen?

[rama777]

I have a but of N toxicity that developed. I wonder if it’s also potentially from excessive calmag. Would there be any indicators that would help tease the two out from each other out if they were happening at the same time?

[mrgrowit]

Well many brands of CalMag actually have some Nitrogen in it as well. So that’s what could be darkening the leaves in the scenario I was mentioning.

The only way you can know for sure is tissue and soil testing, which isn’t feasible for many due to cost. So the cheaper route is to check the EC/PPM of the runoff to get a general idea of the amount of nutrients in the medium and then make adjustments from there. Some prefer a slurry test instead. Also, some growers are against runoff measurements for one reason or another but imo it’s better to have and use that measurement than nothing at all.

[rama777]

I specifically got calmag that didn’t have nitrogen in it. I think I’ve just overfed nitrogen some.

Git some silica today. Do you have any recommendation on how much to use and how often? Is it cool to mix it with calmag?

[rama777]

So I bought a cheap moisture meter. I have been watering every 3-4 days with 5-7% volume of water depending. What I’m noticing is that I think the very bottom 2” of the soil is dry. For 7 gallon pots. How much do you think would be a good amount to bottom water them to moisten the bottom couple of inches of soil?

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