Most nutrient manufacturers base their formulas on the assumption that you will probably be using normal tap water (EC 0.2 - 0.4) which already has some calcium and magnesium in it. If you use RO water you will have nothing in there to start with. Canna calmag agent can be used with very soft water like i have here OR with RO water. Just add enough to bring your water up to an EC of around 0.4. Then you add in your choice of nutrients till you reach your desired total EC and check/adjust ph if necessary.
I’m growing in coco so i never exceed EC 1.4 and that’s only for a short time (mid bloom). I let the ph drift between 5.5 and 6 to make all the nutrients available. Most mineral nutrients these days are chelated and should be available over a fairly wide ph but iv’e been caught out before so i still adjust the final ph.
@Albannach - Thanks. Very informative. In relation to the pH swing, I have a pH controller for my flower tent. My plan was to have the controller set to add enough pH down to swing it from 6.0 down to somewhere around 5.2. The pH adjustment would happen in my control res. This would then slowly circulate into the bubblers resulting in a final pH of about 5.6. So in effect the pH at the plants roots would swing from 6.0 down to 5.6 in about 30 minutes. I have float valves to then slowly top up the control res with pH adjusted water at about 6.2 which should slowly swing the pH back up to 6.0 over a couple of days at which point the pH controller would kick in again. I don’t suppose you would know if the swing from 6.0 down to 5.6 over 30 minutes would be too fast and cause shock would you?
I would recomend as little swing in pH as possible. You should really keep to 5,6 and 5,8 at max in hydro. The plants will get to use to it. Little swing is desired but rather in lower pH than Above 5,8 I would go from 5,5 to 5,8 idealy. I only watered with pH 5,6-5,7 and plants are growing Just Fine Coco grow
Hmmmmm, to swing or not to swing. That is the question. I have noticed there are the two trains of thought on this. Both reasonings have their meret, sound logical and produce good results. Which only makes my decision harder.
A small swing from say 5.5 to 5.8 (max 6) in hydro across the space of several days used to be considered a good thing but i suppose this is old hat stuff nowadays with most of us using chelated nutrients.
I find the ph in my grows usually drifts up the way so a nutrient solution around ph 5.5 is often needed just to keep the root ball ph from going too high. My tap water starting ph is around 9 so i’m not surprised it wants to drift back up the way over time
Coco grow 