Glad I found this thread. Lots of interesting info here. I’ll add my two cents for what it’s worth…
I grow in coco/perlite DTW. I run the standard 3-2-1 system with RO water, using silica (typically armor si or silica blast) and Diamond Nectar through the entire grow cycle. I tried the Jack’s RO formula once and had terrible results so I switched back to the 5-12-26.
I run my EC quite low (<1.5 EC/750ppm), apparently. I didn’t realize I was so much lower than most until joining this forum. That said, I have harvested well over a lb. of absolutely fragrant and delicious herb from my 4x4 tent on multiple occasions, so I’m wondering if I should mess with something that isn’t broken. Maybe I’m just lucky with strain selection so far but I’ve run into no issues with obvious nutrient deficiencies or anything like that.
The only thing I really futz with throughout the cycle is the PPMs. When they’re seedlings, I dilute the solution to <300 ppm, then gradually increase over the next handful of fertigations until I don’t have to dilute anymore.
I agree with this completely. I bought an erlenmeyer flask and a magnetic stirrer and it made my life a lot easier. I bring my water to a boil in the flask then set it on the stirrer. I add my part A (etc.) and come back a little while later. Zero sweat, all done.
The only other thing I can think to add is I’d recommend people check out episode 74 of the Cannabis Cultivation and Science podcast, with Dr. Cari Peters of JR Peters. https://www.youtube.com/watch?v=vi42IFRfNA8 It’s been a couple years since I heard it but it was at a time when I was on the fence about using Jack’s. I was quickly no longer on the fence after listening. Good stuff.
If anyone has interest in an entire bag of Jack’s RO formula, I’d be happy to pass it on.
I’m curious why you heat the water as far as a full boil. Room temp water dissolves Jacks really well, especially with a magnetic stirrer. If you want to get crazy, you can heat it up to lukewarm (90-100F) to dissolve even faster. But maybe this is for concentrate?
I stopped using a magnetic stirr because it strips some iron from the solution. Next time you stirr look at the bar, that black stuff sticking to it is the iron.
I very much doubt that it’s pulling enough metals out of solution to make a difference. If you can prove it, please post test results proving using a magnetic stirrer versus another mixing method makes a difference in the iron content in your nutrient solution. Otherwise this is nothing more than bro science.
I haven’t done a w/ and wo/ side by side experiment, so I can’t say whether or not it makes a huge difference. With that said there is no denying some iron is getting captured by the stirr bar.
Then again maybe I ended up with an iron rich lemon bag?
I would still need extremely accurate instruments in order to get conclusive evidence.
Again, does it make a huge difference?? I wouldn’t waste my resources on it when simple options are available, like that of @DougDawson, or a big spoon.
I agree. I looked at those magnetic stir things but they were pretty pricey and I can’t see them doing nearly as good a job as my $18 mixer on my drill. Turns the 5 gallon buckets into a whirlpool that creates an opening to the bottom of the buckets. But to each their own.
The stir bars get dirty after a while, but if it was actually iron or something actually getting pulled out of solution I’d expect Google would turn up something. The closest I can find is that they get micro-abrasions and contaminants (not always metals) get embedded in the magnetic stirrers, so they need to be replaced periodically.
If they actually caused issues, people like Daniel Fernandez would advise against using them. But I see him using magnetic stirrers interchangeably with shaking & stirring by hand, which tells me there’s no issue with them. They’re not the cheapest option, but there’s no reason not to use them if that’s someone’s preference.
Magnetic stirrers can be had for as low as ~$35 cad. They do as good a job as any other stirrer… they’re made for stirring.
I have two. Just wish I’d invested more and got a (quality) heated one. That’s where the expensive ones are, even the not-so-good ones are pricey. Magnets and heat don’t mix, which is a main reason for the high cost of the good quality ones.
You’re not going to be able to check this (iron) with your ec meter.
Besides, if you wanted to try and check this in a similar type of way, why not run a magnet through the dry fertilizer and see if you pull it out with a bunch of iron on it?
For mixing up to a gallon at once I like the magnetic stirrers. Can’t be beat for the ease of use with small quantities, at least in my mind.
If I’m mixing more, like 5 gal at once for plants without individual needs (not especially light or heavy feeders), the drill bit mixing paddle Doug Dawson posted is much easier. I have one of those too. But even that falls short if you’re looking at 20-30 gal at a shot. Basically comes down to the right tool for the job.
I typically mix a 2x solution into a gallon with the stir plate then dilute down with ph’d water per each plant’s needs. 2x settles with my tap water at 5.85 so no ph’ing and my tap takes 1 ml ph down to be right around the same. That way I don’t have to fiddle with the ph pen at all. Its money.
Thanks for the tip.
I wouldn’t waste my resources on it when simple options are available, like that of