[Rex Grigg]

Calcium Nitrate which adds 2.24 ppm of Calcium and 10.5 ppm of nitrates for each gram in 10 gallons of water

or

Calcium Chloride which adds 9.5 ppm of calcium for each gram in 10 gallons of water?

I will most likely carry one of the above.

 

[PineyMike]

This is tough. I guess you could look at it two ways. Since KNO3 is used the most and you have to usually order 3X more of it than the other dry ferts it would be nice to have the calcium with nitrates so you could order less KNO3. On the other hand, people who have their fert routines balanced out perfectly might not want to mess around with having to recalculate things to account for the nitrate in the calcium. For me I think Calcium Nitrate is better based on the levels already in my tap wtaer.

 

[spypet]

I'm in the Calcium Chloride camp.
My tank already generates more Nitrates than my plants need,
so I never have to dose Nitrates or even Phosphates in my tank
especially since my tap water is already 2ppm Phosphate.
Besides, Nitrates are cheap, then it's better to have CaCl2
so people can control their Nitrates and Calcium separately.
After all, isn't that the whole point of dosing powders
beside the lower cost, and greater preparation work.

 

[Minsc]

I'm more a fan of Calcium Sulphate aka gypsum... I'm happier adding tons of sulphate over tons of chloride... but out of the two I vote Calcium Chloride.

Calcium nitrate seems a good source of NO3 if you don't want to add any K for some reason? You would have to add a ton of NO3 to significantly change your water hardness... but maybe someone is trying to add only traces of calcium?

Calcium chloride seems good, but there have been reports of stunting issues when too much is added.

I guess personal preference is going to run along the lines of whatever flavor of the month dosing theory one believes...