used ro and forgot the calmag

[Dividedsky]

Does calmag always need to be used when you use r/o water? I've been using half r/o half tap no cal/mag to save on water bill, plants look fine. Fed with 10gals of straight r/o water last night and forgot to add the cal/mag. Is this a big deal? Could I notice a deficiency in the next few days. I think i'm going to water with half tap half r/o water because it brings my ppms down to a managble level and I'm not wasting so much fucking water. Im could be watering with 20gals every 2-3 days and thats not even counting veg rooms.

 

[MeJuana]

In flower I do this sometimes and I get stressed, watch the plant closely and it's no big deal but if you do it a few times in a row you will see a response. Younger veg plants take it a little harder but they straighten right back out.

 

[Dividedsky]

In flower I do this sometimes and I get stressed, watch the plant closely and it's no big deal but if you do it a few times in a row you will see a response. Younger veg plants take it a little harder but they straighten right back out.

ya I've done it before also ...noticed bottom fan leaves seem to get stressed

 

[Kingrow1]

I think the tap water provides very little calcium but greater alkalinity in the way of insoluble calcium carbonate and the calmag provides loads of calcium in the form of dissolved calcium nitrate but little alkalinity.

 

[Richard Drysift]

I use RO and/or reclaimed water from a dehumidifier & been doing it for years. I don't always give cal/mag at every watering either. I give it every other time but sometimes forget; the plants won't care just give it to them as regularly as you can. Usually purpling stems are the first indicator there's an absorption problem; if mag rust is evident it's a bit more severe case.
Magnesium is one of those elements that help the plants uptake the other npk & macronutes in your mix but it's not that easy to provide it in a soluble form that's readily available to your plants. You can add soft rock phosphate which is rich in mag as well as iron & a ton of other good stuff but it takes years to break down. Molasses will provide soluble magnesium in a pinch; just bubbling it will help release it but this is only a quick fix. Adding composted eggshell will provide calcium but again needs for microbial activity to intervene which can take a long ass time. I feed crushed eggshells to my worms & they help break it down a bit before adding to my recycled mix. I still need to give an organic liquid cal/mag though to keep the party rocking in my containers but they don't seem to need it as much as they did before I started recycling my mix; it gets better with age. My point is that while you need to give liquid cal/mag for now fairly regularly you can back off a bit in the future if you provide a source of macros in your mix globally. Hope that helps good luck happy growing