Nutrient Solution EC dropping. No (visible) precipitates.

The plant can take in nutes in 3 different ways, 2 are more important -- "mass flow" is simlpy what can physically diffuse across the roots membrane. physical size is a big part of that equation. there is also 'active transport' which sends out molecules to 'grab' nutes and re-enters plants - it's a bit more complicated than that, but that is the gist. This nute intake is selective and specific. the plant realeases certain molecules to grab certain nutes. This could cause your EC to drop because nutes are taken in but water is not. So the substrate around the roots is being leached of nutrient molecules but water volume stays the same = reduced EC. But regardless, this doesn't matter because it is normal. What matters is consistency of nutes around the roots. What matters is how the plant grows. you should not be adding some nutes here, and some nutes there. It should be all added together when you fertigate. you give a full diet and you get 10% runoff. Each time you fertigate it 'resets' the substrate around the roots, all is well. coco isn't magical. As long as it was buffered properly you treat it no differently than any other "soilless" growing medium. stop the ocd measuring behaviour. It's good to measure, but you have no baseline to compare to understand/discern what is normal or 'best'. it's just what you think it should be and that is a dangerous way to approach it. When you have the plant growing awesomely, you'll see this stuff you are measuring is still going to fluctuate a bit and it's normal. AFter you've observed and adjusted the formula to optimize growth, then you'll learn what is normal wtih the EC over time in the substrate. Don't assume things in a top-down way. Let the plant dictate. The resulting growth is what matters not our feelings on how it should be happening. Growth is the guide. Soilless is simple -- well-balanced diet each irrigation. 1.3-1.5EC overall concentration not including your tap water's contribution. Always get 10% runoff. Allow 'enough' dryback and repeat. KISS - keep it simple stupid. if you aren't fertigating/irrigating in this way, you are doing it wrong and that isn't an opinion. The 10% runoff matains an equilibrium relative to your fertigation formula. It will be consistent even if it's an offset value(s). You can work with consistent - it's value-added. At this point the only time you can get a toxicity is if your formula is too heavy in that nutrient. it will never be because of a buildup in the substrate, if religious about 10% runoff --- even if the resulting equilibrium is slightly offset from your formula, it will be consistent, which allows you to adjust the formula and immediately impact the concentration of nutes around the roots. Diagnosing is easier.. adjustments are easier... it's really simple stuff, or it should be. 120-130 N -- I drop this to 100-110ppm in flower to avoid buildup. 40-60 P 180-190 K 100+ ca 75is mg 100+ S (sulfer not Silica) Si (siica) - not sure.. think you only want 10-20 ppm? i'd read into that a bit or stick to their instructions on whatever product you are using. i don't use Si products. I'm going to experiment adding an amendment to my substrate this year that does add available Si (DE), but never used it before. It's usually tough to overdose on silica, but some of the products out there definitely can do it. this is a low EC. It's a safe spot to start and based on local variables you may need more or less, but the ratios are rock solid. Ratio of nutes is equally important to overall concentration. How concentrated you want it will depend on VPD among other factors. These are ballpark numbers and "close" (within 5-10%) is often good enough. hydrobuddy is a free app that can take your guaranteed analysis labels and give you ppms. or using your labels tell you the dosage to hit these target ppms etc... Then, observe and adjust for consistent, awesome growth no matter how many strains you grow at the same time. ------------- You got some really bad info below that needs to be corrected -------- omg... ultraviolet that is the opposite of what you want to do, lol. Always add Ca and silica last - Si, then Ca last. This is well-known and can be verified with a cursory google search. This is basic chemistry, lol. Don't take my word for it and definitely don't take ultraviolet's. calcium nor magnesium cause issues with EC. You should fee free to add these all the time, since the plant needs both calcium and magnesium at all times. Again, in soilles each irrigation should be a full diet (simplified - you may want a different diet in bloom compared to vege, for example) When coco is buffered, it does not leach Ca or Mg. The fibers breaking down are irrelevant at least in the time frame of of a grow cycle and the fact that water absorbs into it and does not only interact with the surface area of the fibers, lol. The CES (cation exchange sites) were already 'buffered' so that it doesn't leach Ca and erlease Na+ or K+ etc. Buffering coco gets it to an equilibrium with your typical ratio of fertilizer nutes. as much Ca is bonding to CES as being released. It may takes a few fertigations to 100% match up but should avoid any sickness. IF coco is not buffered, it makes plants sick... it's a dangerous medium to use for this reason. You put a lot of trust in the manufacturer of the coco not to fuck up your garden. I used coco for 2 years due to convenience.. 70/30 coco+perlite ready to use is convenient. I've since switched back to promix hp/bx + vermiculite (to 50% of volume with existing perlite that comes in the bale). I had couple bad bags of coco and luckily it only slowed down growth vs causing some fucked up Na+ sickness and potential death. That scare was enough to push me away from coco. When ths ultraviolet guy tries to talk in a scientific way it's often wrong. He thinks humidity rises, too. also, remember calcium and magnesium are their own molecule/nutrient. they are not "together." they are unique nutes with unique requirements. too often people talk about them as if they are linked or cause the same things when deficient or toxic. N,P,K,Ca,Mg.S are all unique atoms.

When adding silica to your water, always add Silica first, stir, then add fertiliser.This way the silica will not bond to other molecules, rendering it unavailable to the plant. On a other note, Is tough to correct while plants are growing because Cal Mag supplements have a strong impact on electrical conductivity (EC). As a result, the total dose of CalMag that you can provide is limited, even though it all may be going to the coco and none to the plant. Coco is constantly breaking down. As large fibers of coco break down in the pots they expose new surface areas of the coco fiber. This also exposes new cation exchange sites that will take Ca and Mg from your nutrient solution and reduce the amount available to the plant. Good luck.

My guess is that the solution is separating or something and settling to the bottom,? that's the only reason I could think,or some sort of conversion is happening when mixed into water. but I'm not exactly a chemist so that is just my speculation