Has anyone experimented much with this? From my use of calcium reactors and propagating coral for decades I have a lot of this stuff laying around. Since it’s mostly insoluble at PH levels above 6.4 and the needs of cannabis fall a little below this range it seems like it could be a good compound to prevent PH from dipping, especially in the flowering stage where it’s better to have a PH on the higher end of the range.
Any experiences or flaws in my thinking that anyone sees?
20 + years ago, when I first started building a NewGanjaBoy stealth cabinett, it was the aquarium folks where I got a lot of ideas from. I’d try that out if I had everything here myself.
AFAIK the resident coral tank expert here is @Nagel420 I imagine they have a lot of knowledge about this
Awesome, thanks! My reefkeeping has helped me a lot, especially with understanding nutrients and how to setup a RDWC… Anyone with some solid chemistry knowledge should be able to help as well.
I’m also considering using a PH controller, CO2 (since I have it), and kalkwasser (limewater, calcium hydroxide) to keep PH from dipping and for auto topoff, so anyone please feel free to chime in on that as well.
Thanks again!
It’s far easier to dose calmag or add alkalinity in any of the other soluble calcium forms than rely on sand to provide it. If you’re using hydroponics you want variables you can control and account for.
Reef is harder than hydroponics. You’re already set lol.
Yeah, this stuff has been easy and fun compared to coral farming 
I’m going to automate it one way or another likely using CA(OH)2 and just eliminate the use of cal mag, which I’ve basically already done. I think my RDWC will be easy for that. However, I was considering experimenting with bubbleponics since I’ll likely have a few of those going as well. That’s what gave me the idea since I’ve noticed the instability and swings being much greater and was contemplating is calcium reactor media or aragonite in f the bucket might help. I’ll probably be reporting back later on this if I keep seeing PH drop.
You might be able to replace Calmag with kalkwasser but there’s no magnesium.
K, Ca, and Mg can have an antagonistic effect on one another. You can overdo calcium and it creates its own set of workarounds. My water is incredibly hard for example. You’d need to monitor things.
It’s fun to experiment but always remember there’s often a good reason why no one uses reef calcium reactors/etc. Ca demands are much lower.
I’m using 0 TDS RO/DI mostly, with the occasional tap water to raise PH (110 ppm CA in the tap). Kalkwasser does have magnesium, but if memory serves it’s insoluble, despite some companies claiming that it will help with Mg levels… Magnesium sulfate once or twice during the grow seems good enough for Mg needs of cannabis, and I’ve been using that already.
No intention of using one of my reactors since I think alkalinity needs can be met without active CO2 injection. Plus, it would just be dumb to use an $800 device for something that simple. Though I will end up using one of my peristaltic pumps or dosing pumps to dose something to keep PH stable at some point… It just won’t be one of the cole parmer units I have…
I thought about that for calcium supplementation, but haven’t played with it much. My concern is the higher pH of kalkwasser would possibly raise the pH in the res too much. Aragonite on its own, aka coral rubble, will raise the pH on its own as well. We used to recommend it as a substrate in FW tanks with Cichlids requiring higher pH levels…
A reactor is overkill… For sure… But mixing a kalk slurry for some calcium has merit, but like @vernal said, still need to add some magnesium then. I just get lazy and use epsom salts and my tap is high in calcium to begin with. I dont see a major need to use RO / RO/DI for the plants considering I am soil and my tap water is pretty good for the most part, just a little hard, but neutral pH.
Your reefkeeping knowledge will certainly give you a leg up with the garden. I used to farm corals myself, had over 1400 gallons at one time, including a 300g show reef. I was also a staff member on RC for a number of years and even worked on the beginnings of RK mag… Then I got divorced… Now I just scuba dive and have the biggest reef tank in the world instead 
LOL
Are you thinking of cruising dead coral. I have been thinking of trying that and/or leaching it in vinegar like egg shells. I have lots from tearing down my saltwater tank!
Awesome, good to have a fellow reefer and RC’er around! I got TOTM a little while back right before RC started really going downhill.
I’ve been using kalkwasser sparingly already, and it seems to help with stabilizing the PH.
Thanks for chiming in!
Yeah, I have bucket loads since my fully mature sps tank did not like the move! I also might try TLF ca reactor media