Dwc

I have done a few dwc grows and similar happened to me, I found like others have mentioned she was taking up more water then nutes. If memory serves me right I think I got to an Ec of about 1.6 when this happened so I lowered the Ec to 1.4 and it stayed stable at this. Try lowering the Ec by 0.2 and see how she reacts.

EC is electrical conductivity, not concentration. It loosely correlates but the fact that the various conversion factors used have a 40% range, that should tell you it's not a very accurate conversion. Selective feeding may not result a 1:1 change in EC. Plants look healthy. No signs of toxicity. If concerned do a full reservoir change more often than what you currently do (in this case doesn't seem necessary, but whatever floats someone's tuna boat). The plant doesn't take in nutrients all together or in same proportion to drinking, so the 'theory' mentioned is not actually how it works. .03-.05 is also probably within the error range of your device. Even if not, a change in ~15-25ppm isn't really a concern. Or 40% less than that if the probe uses a 700-scale conversion for EC-PPM (on top of the error of the device, highlights the inaccuracy)... EC is important, but not super great at precisely measuring concentration. This is part of why soilless needs 10% runoff and why hydro needs an occassional full reservoir change. The nutrient ratio will shift over time due to selective intake of nutrients. You don't actually feed at proportions of how it is used in the plant. The best ratios allow each element to be readily availble - a slight but important difference.

Hey TheVomit! When your EC rises while the water level drops, it’s actually a sign that your plants are drinking more water than they are consuming nutrients. Even though you think you should be at 1.8–2.0, the plants in theimage are telling you they've hit their limit for now. If the EC goes up, it means the solution is getting too concentrated, which can lead to lockout or burn. I’d recommend backing off the nutrients slightly until the EC stays stable as they drink that’s the "sweet spot" where they’re eating and drinking in perfect balance! Happy Growing Growmie🌱

Very large plants for size of rootzones. Its asking alot, this is long but will give you all you need to rectify. For every molecule of carbon you wish to convert it takes 6 molecules of water. For every molecules of carbon converted to glucose using aerobic (oxygen) cellular respiration the plant will bank 36-42 ATP. For every molecule of carbon converted to glucose using anerobic cellular respiration the plant will bank 2-3 ATP. When roots are submerged without sufficient oxygen ,hypoxia occurs they switch from aerobic to anaerobic respiration, creating a hostile environment that affects nutrient solution chemistry. Lots of lactic and carbonic acid is released, the resulting pH drop from these acids can cause certain nutrients to precipitate and become unavailable to the plant, further skewing the intended nutrient profile/ Ec in unexpected ways. You must restore the aerobic environment. high level of oxygen is key to avoiding these anaerobic fluctuations and ensuring the EC accurately reflects what your adding. Plants adapt to Deep Water Culture (DWC) by significantly altering their root architecture—often developing thinner, finer, and more extensively branched roots to maximize nutrient uptake in an aquatic environment. While it is true that plants exude up to 40% of their carbon into the rootzone, this process changes in DWC where the water "absorbs" these sugars and organic compounds, making them a significant part of the dissolved organic carbon in the nutrient solution. DWC water will also over time absorb CO2 from the air if exposed to a source of fresh air so its important to understand how the levels of co2 present will afeect absorption rate. Salt ions attached to carbon will not present towards the EC. While carbon itself (in organic form) doesn't always conduct electricity well, the methods of introducing it—or the consequences of having too much—significantly impact the ionic balance and, therefore, the EC reading. Best of luck with final weeks.

From what you describe, the EC rising after water consumption usually means the plant is taking up more water than nutrients, not that it is “not feeding.” This often points to imbalance in uptake rather than lack of nutrition. First make sure your EC and pH meters are properly calibrated, because small errors here can completely mislead you. Then check root health and oxygenation, since low oxygen in the root zone will limit nutrient uptake even if the solution is correct. Also consider environmental factors like temperature, light intensity, and VPD. If transpiration is high, the plant will drink more water than nutrients, which causes EC to rise. If everything above is fine, your base EC might simply be a bit too strong for this stage, so lowering it slightly can help restore balance and stabilize uptake.