CAl-Mag and RO question - Should be easy

Just got a quick question that i want to double check my thoughts on just to be safe. I am using RO water and GH 3 part nutes. On the GH feeding schedule, it says to use cal-mag ( i am using the GH CaliMagic not Botanicare) at 5ml per gal for the first 2 weeks if using RO water.But only for the first 2 weeks?? I have been using 4-5ml per gal every feeding.Just want to get a general consensus that i SHOULD or SHOULD NOT be using Calmag with every feeding if i am using RO water. I was under the impression that i should, but just trying to get the N down in my mix a little as my girls have just a little N toxicity. I have flushed and corrected the problem, but it is a reoccurring issue. I can adjust my formula a different way if i need to be using Cal-mag every feeding to get the N down, but that would be a quick fix.Any thoughts are really appreciated! Thanks!

I use calmag in every watering ... it adds the cal and mag that r/o doesnt have in it ..

happy growin

I use it every time I mix up a batch of nutrients because I always start with RO water. It's not going to hurt anything. Are you sure you have nitrogen toxicity??? (very odd thing to have with cannabis.) You are using a GH feeding schedule, so I am curious as to how much fertilizer you are using.

Yeah.. absoultely sure its N toxicity. I almost always get it. Super SUPER dark leaves, and if i let it go too long it starts to degrade further, and there is a noticable bump in growth as soon as i get it handled.

I found out this particular time, my meter was about 400 ppm off (reading low). I try (now) to keep my PPMs no higher than 1000 however, i had it all the way up to 1600-1700. that and was watering too much / too often and they were just getting over fed in general, but my strains always show too much N first. I was not using the GH schedule at that time, it was a friends that he gave me. Worked well for him...

Yeah, most feeding charts are way off the mark. I started with DG's chart and quickly learned that plants are much more happy with 1/2 the strength recommended. I would continue to use CalMag and dial back the main nutrient a bit. I test my water when adding nutrients and 50ml of CalMag brought my water from 70 to 250ppm (70 because of the addition of 100ml of ProTekt.) Your results will vary but that might be a usable baseline for you.

Same as tellno1, I add cal/mg to every water, for the same reason as him, and also it also lowers the PH of my water to acceptable levels.

roidrage152 said:

Same as tellno1, I add cal/mg to every water, for the same reason as him, and also it also lowers the PH of my water to acceptable levels.

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thats odd. My RO water comes out pretty low for whatever reason. When i switched to my RO, i found myself using a lot more ph up instead of ph down.