Fertilizer tweeking

[consettbay2003]

I currently use Peters Excel 15-5-15 Cal Mag. ( 7% Ca. 3% Mg. ) at the rate of 2 tsp. per 8 gallons of RO water once a week.
I would like to add additional Ca and Mg to this rather than try to remember to occasionally give supplemental feedings of these two nutrients.
How much Ca. and Mg. should I add to the 8 gallons of fertilizer solution?

 

[Rick]

maybe instead of making it up in RO water just use tap water.

What is the conductivity and hardness of your tap water?

 

[Cheyenne]

Depends on where you live and where you water is from but now water treatment facilities are using cloramines instead of clorine. I used to let my tap water sit out for a few days to evaporate it out. You cannot do that with cloramines, the results were a slow decline of many plants. Not enough to notice right away but enough to slow growth more and more over time. Just beware, learn from my mistake.

 

[Rick]

Depends on where you live and where you water is from but now water treatment facilities are using cloramines instead of clorine. I used to let my tap water sit out for a few days to evaporate it out. You cannot do that with cloramines, the results were a slow decline of many plants. Not enough to notice right away but enough to slow growth more and more over time. Just beware, learn from my mistake.

You can pull the chloramines out fast with carbon. Some of the guys down here put a couple of carbon canisters in line on the taps in their GH's. Even a small canister (with good grade carbon) is effective if you run it slow. You could add a sump or barrel with a fill valve so that you have a ready batch between uses.

 

[Rick]

Presently you are using at the rate of 1/4 tsp/gal. Is that the normal rate to get 100ppm of N for this fert?

The ratio of 15-5-15 (7Ca 3Mg) is very close to the MSU RO.

Before we put K lite together, my work around was 1/4 tsp of MSU, 1/4Tsp of CaNO3, and 1/4 tsp of anhydrous MgSO4. (if you want to use Epsom salt then use 1/2 tsp of Epsom).

That still produced about 100ppm N.

Ultimately I cut down to about 50ppm N so cut all of that in half again.

 

[NYEric]

I always put epsom salts in my fertilizer and add a pinch of MSU for the trace elements.