How much Cal/Mag needed in DWCR and Coco-coir

[rillos]

It seems in my growing that my Dwcr system plants show cal/mag def while in my coco-coir don't at the same 2ml per gallon. I thought it was supposed to be the other way around where I would see def in coco-coir before I would in my Dwcr.

 

[Papageno]

Deficiencies when the availability is abundant are due primarily to pH being wrong for the nute uptake. DWC is a bit finicky though on this one.

Not to begin with it is very hard to over do either of thee so it you are seeing a problem adding a bunch wont really hurt. But if the pH is whack it wont help either.

Most charts show Calcium uptake as being good down around the 5.8 norm but in reality it is not and Calcium is one that is much better at a higher pH. Often times in DWC people will run it up to 6.4 or even higher in extreme cases to get good uptake. I have read and I also had a friend do this once where it was really bad so they ran the res all the way up to 6.8 for 24 hours to get the calcium in there and then dump the res and go back to normal.


Notice in the chart below that it can work at 5.8...but works much better at 6.8.

Both Calcium and Magnesium are much better at higher pH's which is why products like AN pH perfect have huge overdoses. You can't really over do it with these two so if you are going to hold pH low you want to run those up.

I find both are easy to fix....just make sure your res is reasonable and add some...but it wont fix bad leaves...those are bad.

 

[rillos]

Ok with this new understanding, how much cal-mag should I be using.

 

[Papageno]

That depends on a lot of factors but mainly how you grow. There are many philosophies to this. What I tell you how I do it will get harsh backlash from people who have only done research and grown hydroponics for cannabis. But fortunately hydroponics works with many plants. So some people will go learn about how hydroponics actually works in general terms and then understand what tweaks are nice for cannabis. These people will tell you vastly different things then people who have only grown cannabis hydroponically and only study cannabis techniques.

Another Big factor that I don't know about, with respect to how you grow, is your stance on Sterile vs. Living res. This matters a lot because in drastically impacts res changes and PPM control and res temps and pH so therefore uptake rates as well as root health so therefore uptake rates.

There are a lot of ways to do it and for the most part every way has its place and is "the best" for certain applications...but nothing is just the "only" way to do it.

I know so little about your setup and methods and experience and skill level that it is hard to say other than do it the Advanced Nutrient way and start throwing it in there until it works.


I always suggest that following a recipe blindly is a recipe for failure. I always try to recommend that people start with researching pH cycling and res stabilization techniques. I can easily go well more than a month between res changes and I do not have to add any pH up or down to the res for the vast majority of that. A little in the beginning and then near the end when it starts to need it is when I give up and do a res change. My good buddy who has been growing for nearly 30 years runs Auto fems in DWC and never changes the res...but he is in and out in 8 weeks. So to answer the question according to how he does it may not help you.