Here’s the system I purchased.. $212 after taxes.. I’ve seen it available for $150 on sale if anyone is interested and is willing to wait for a sale.
In honor of the RO system coming tomorrow I figured this would be a good time to start discussing water. This is a big topic that spans multiple subject areas, which we will cover as we go along.
Water is a critical component of the grow that many don’t think about beyond ph (or something to mix nutes into if that’s your thing). Up to 90% of a plants weight is water in its cells and cell walls. The properties of water allow it to bypass the plant membrane which is responsible for keeping bad stuff out and good stuff in. Water is so important, plants dedicated millions of years and 3 cellular pathways to perfecting their ability to use it.
Water moves into plants in 2 ways. The first way is transpiration (which can be controlled by us with VPD). Approximately 90 percent of a plant’s water loss happens as a result of evaporation through leaf stomata. This process of evaporation is called transpiration. This indicates that as much as 90 percent of a plant’s water comes into the roots as a result of transpiration. The molecules evaporating from the leaf surface pull up water molecules from below. This, in turn, causes a pressure deficit in the roots that pulls in more water from the soil.
Hydrogen bonds keep water molecules stuck together, also known as cohesion. As one molecule is pulled up through the plant to evaporate off the leaf surface so it pulls the next molecule and the next up with it.
This is regulated by tiny stomata cells embedded in the leaf. These cells are regulated by potassium and trace amounts of chlorine.
The other 10ish percent of water comes in through absorption due to “Root Pressure”. Root pressure occurs when there is more water outside the root than inside it. This difference causes water to flow in the direction that will create a state of equilibrium.
Earlier I mentioned VPD.. VPD stands for Vapor Pressure Deficit. VPD is a measure of how much water is in the air versus the maximum amount of water vapor that can exist in that air. This means that the more humid our environment is, the less our plant can transpire. The dryer our environment is, the more our plant can transpire.
So if our environment is extremely humid, our plants will only be able to take in so much water from the soil because they can only evaporate so much into the air before it becomes fully saturated and won’t hold any more water. On the flip side, when our environment is really dry, the amount of water our plant can take in and evaporate off is incredibly high.
As this transpiration process happens, the plant is working its butt off. It’s using energy to synthesize, move nutrients and sap, and all sorts of complex interactions are happening all while water is being pulled into up and out of it. The more your plants are transpiring the harder they are working. This is knowledge we can leverage.
In the beginning we don’t want to drive our plants very hard, they’re still getting their roots, and establishing themselves in this world. As our plants age and mature though they become capable of handling more and more until eventually we find ourselves in flower pushing our plants to their limits. Sound like any other life forms you know?
We want our plants to grow in a relaxed environment where their only concern is to eat and get bigger. We don’t want them working their butts off just to keep themselves hydrated nor do we want to try to push our plants processes until they’re ready. Similar to how we don’t allow children to do specific tasks until their bodies have matured or we risk doing irreparable damage to them.
We want to wait until the system is completed and ready to handle what we can throw at it. Going with the children analogy, this also means that yes, we can ignore science and knowledge and push our children anyway, and most often, they won’t die. However, their quality of life in the long term will most likely suffer greatly due to the damage inflicted on their immature systems. When a plants quality of life is affected in such a way we see the results in our yields, quality, and overall plant health.
So now we know how water moves into and out of the plant and that we can control the rate of the majority (if not all, we can indirectly impact absorption by not allowing water to evaporate) of this movement. Understanding this also alludes to some pretty big implications which we will go over.
None of this covers nutrients, sap, or the myriad other wonderful processes water is a part of but we’ll get there, water movement is a big topic by itself.