Hydroponics, i need a second or third pro opinion. Just a Deficiency? bad pH? (I alreadt did a partial water reservoir change tho)

probably locking out calcium at 5.3 or at minimum requiring large amounts to overcome it. If you fix the pH you may need to lower Ca, if you've adjusted it upward previously as an attempt to fix the ongoing issue. A new pH will require slightly different ratio of nutes... whether that change is substantial enough or not, you'll find out soon. double check for any growth on roots, too.. brown/slimy/stinky would be bad signs. Some portion of nutrient elements rely on 'active transport' - which is the plant sending out carrier protiens to attch and transport a specific element back into the plant. This means it can selectively pull things out and that can cause a ph-shift. Better hydro nutes are well-buffered and should mitigate this possibility in more cases than not. If pH balancing is not maintaining your pH over time, consider better hydro fertilizers that don't require such efforts. Any professional Ag company would sell ph-buffered nutes for a hydro context. Only an amateur hour operation would do otherwise, which is a good chunk of marijuana fertilizer brands, sadly.

If you're running that low of pH consistently, then yeah it might be preventing the uptake of nutrients. If it's part of your general "swing" between fresh tanks then I kinda doubt that's it. I wonder if you're supplying enough O2 when combined with the droopy look. What might seemed sufficient for a small plant might not be enough as the root mass expands.

The term ‘relative humidity’ (RH) refers to the amount of water vapor in the air and is usually expressed as a percentage (e.g. 50% RH). This can have a major impact on how cannabis plants grow. Low humidity means less water in the air and results in increased evaporation and water use. Excessive humidity comes with its own problems, including creating an ideal environment for pests, mildew, and mold to grow. One key factor related to humidity that is often left out of the conversation is vapor-pressure deficit (VPD) – the difference between the maximum water vapor the air can hold at a given temperature and RH. Although not all growers measure VPD, it significantly influences stomata activity and is directly related with transpiration rate and metabolism. A VPD that is too high means drier air and increased evaporation and transpiration. Too low a VPD can lead to slowed transpiration and reduced growth. Since slowed transpiration reduces nutrient uptake, both too high and too low of a VPD may appear as nutrient deficiencies. It is VPD that drives transpiration and nutrient uptake in plants; the uptake of water at the roots is determined by the loss of water through the shoots, and the loss of water through the shoots is determined by how much water is in the air. Humidity levels influence the rate of water evaporation from the leaves of cannabis plants, which directly affects the tension and suction created within the plant. Higher humidity levels can reduce the rate of evaporation, potentially impacting the negative pressure and water transport efficiency within the plant. Magnesium is distinguishable by interveinal chlorosis, brown blotches look more reminiscent of calcium. We know your ph is out of whack. Acidic soils with low pH, plants have reduced access to nutrients like calcium, magnesium, phosphorus, and potassium. This is what symptoms you see. During daytime your plant photosynthesizes. During night your plant performs cellular respiration. When you run 75%rh the plant closes its stomata to prevent drowning in the moist air. The stomata are made for has exchange. During the night all the energy thay was collected is processed all night long. The pla t needs to have air space to eject wayer vapor from leaves. As a by product of creating sugars and proteins the plant ejects excess water molecules into the air. If there is no space for the water in the air then cellular respiration will cease and the plant will process a fraction of energy collected. If the plant cannot release water vapor it cannot uptake new nutrients as water is the transport device within the stems. If you keep feeding and feeding and feeding but nothing is being uptake due to 75%rh preventing or greatly reducing tranpirational footprint. You need to get your rh to 45-50% and hold. The build up is causing ph drift. Correct your environment and it all goes away. 👍 The cohesion-tension theory explains how negative pressure enables water movement from the roots to the leaves of a cannabis plant. As water evaporates from the leaf surfaces through stomata, tension is created, generating a suction force that pulls water upwards through the xylem vessels. This process relies on the cohesive forces between water molecules, forming a continuous column for efficient water transport. In cannabis plants, xylem vessels serve as the conduits for water transport. These specialized cells form interconnected channels that allow water to move upwards from the roots to the leaves. The negative pressure generated through the cohesion-tension mechanism helps drive the water flow within the xylem vessels. Negative pressure facilitates the movement of water from the soil, through the roots, and up to the leaves of cannabis plants. It helps maintain proper hydration and turgor pressure, ensuring the cells remain firm and upright. This is crucial for healthy growth and structural support. Negative pressure transports water and aids in the uptake and transport of dissolved nutrients within the cannabis plant. As water is pulled up through the xylem vessels, essential nutrients and minerals are transported along with it, supplying the various tissues and organs where they are needed for optimal growth and development. For a more comprehensive guide to setup decent negative pressure and vpd check chapter 10 week 13 of my dairies. Good luck. 👍