Cal/mag additives for coco coir

[phxazcraig]

I read that coco coir sucks up calcium and magnesium, so we have to supplement feedings with some.

How long? Is there ever a time that the coco coir has saturated itself with cal/mag and doesn't need any more?

I've been adding 1.9-2.5ml/gallon since the beginning, more at first. With buffered coco coir (Organic Roots).

Each dose of Calimagic boosts my EC by about 200 microsiemens. The coco coir has been getting it daily since Jan 15 or so. Would love to eliminate that EC dose, if unnecessary. (Am wondering too if it simply builds up.)

 

[NorthernOrganics]

From what I understand, coco absorbs magnesium and letting it dry out exacerbates this, it should stay watered. So the problem I see with just throwing calmag at it is if the coco absorbs mag and you supplement both, then you will end up with excessive calcium. Are you using RO water? If so, you should supplement calcium and magnesium regularly. If using tap water, you should have calcium and magnesium available and can supplement what the plant needs when needed. Watering coco should be done to runoff in order to prevent buildup of excess salts. I'm a soil grower myself, so maybe some coco wizards will chime in.

 

[DanC520]

I run start to finish as part of my base nute schedule. 1 teaspoon per gallon in veg, .5 in flower. I’ll run a little stronger through mid flower if under led.

 

[jguit]

Or you can use a feed that has plenty of calcium already in it.

 

[phxazcraig]

Thanks for the replies, but I'm still looking for an answer - can you saturate coco with cal/mag (at normal doses) and basically just be uselessly wasting it.
What does coco DO with the calcium that needs constant replenishment?

 

[jguit]

The CEC of coco will hold on to some calcium. Buffering takes care of this but as the coco breaks down it exposes more cation exchange sites, therefore the need for a little extra calcium. Calcium has a double positive charge, so the media will hang on to it moreso than cations with a single positive charge such as potassium. That's my very basic understanding of what's going on.

 

[phxazcraig]

The CEC of coco will hold on to some calcium. Buffering takes care of this but as the coco breaks down it exposes more cation exchange sites, therefore the need for a little extra calcium. Calcium has a double positive charge, so the media will hang on to it moreso than cations with a single positive charge such as potassium. That's my very basic understanding of what's going on.

I guess what is happening is that the coco is slowing dissolving/breaking down and as it does that, some extra calcium is needed. I'm starting to wonder if far less is needed than I'm using.

I'm still seeing my EC rise with each and every watering. After a few days I'll throw a few extra gallons in there at once to flush things down. But after that, the runoff EC rises about 50 points per watering. Yesterday I refilled the reservoir with EC 1350, and initial runoff was around 1650. This morning it was up to 1950. I'm starting to think that almost none of the calcium is absorbed by either the coco and the plants and simply builds up, raising runoff EC. Working theory with no data to support it. I wish I could analyze my runoff to see just which salts are building up, and which ones are not.

Or, maybe it's the Floralicious, which I started applying at flower, and which mostly coincides with the EC runoff rise.

 

[11Hick11]

How many times a day are you watering? To lower the runoff EC would require more fertigation's to get it closer to your impute EC. OR more runoff at the current impute.