Chloride vs Nitrate

Dirt Bag

Member
After finding out that I need CalMag because I now use RO water I was shocked by the cost of commercially available products, did a very small amount of research and discovered that it is very inexpensive to just make my own.
I also discovered that commercially available products all contain nitrogen, which is great... most of the time... for most plants. But cannabis isn't most plants and nitrogen, though extremely beneficial during the vegetative stages, isn't as desirable during flowering.
Making my own supplement gives me freedom to change the recipe to better suit my specific needs. So I ask;
Would calcium chloride be a better choice than calcium nitrate to use with magnesium sulfate and iron EDTA for hydroponic growers using RO water in the latter weeks (or all of) flowering?
Are there any dilution restrictions or problems with CaCl2 as there are with CaNO3 (like precipitation)?
 

ruwtz

Well-Known Member
I use RO and I feed with combinations of dry salts including ca-nitrate, growing in coco. I reduce ca-nitrate around bloom week 4 by about half; at that point the calcium has buffered well and further pushing N hugely inhibits flower growth.

Calcium chloride is a good Ca source and a decent sub for cal-nitrate when the N isn't wanted, as in mid to late flower. Apply with caution as excessive chloride can damage roots. It will also leach salts from the medium, which again can be beneficial late into flower if you're prone to overfeeding.

I add only if I think it is needed, unlike the rest of my standard nutrient sources.

I also have ca-carbonate (aka ag lime) on hand, but I find it is much less soluble and messes with pH.

Regardless of source, calcium will precip out if not diluted properly, either in a reaction with another nute (eg. Mg) or if the pH is way off (eg. K-silicate sends pH up to 9 and must be brought back down before calcium is added or it will crash out).

My first dilution is always working from stock solutions to avoid adding pure salts to a res. This helps to avoid any reactions, and is actually a simpler way of working day to day (no weighing out etc).
 
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