I've only started using my pH meter fastidiously as of late and I've noticed something. I water by hand and try to have 30% run off. I will pH my nute solution to 5.8 as I've been advised. But I've noticed that if I leave a bit of the solution in a glass and measure it again a few hours later, the PH goes up substantially (i.e., it will be 5.8 at the time of waterings, but like 6 hours later it's 6.2). 24 hours later and it can be still higher. I water with tap water that has a ppm of about 100 and a ph of 7.3 -- it's Toronto city water, nothing hard. Is this normal? I recall reading that pH naturally wants to drift back to a neutral state so I figured it was normal. I'm just worried that my plants might be experiencing lockout. This crop does not look as good as I hoped, but I'm new to the Canna line and still fine tuning. Last question: if my nute solution going in is 5.8, what should my runoff ph be? Thanks. I'm using A/B, a bit of cal mag, rhizo and cannazym.
it is normal when adding Cal/Mag to your nutrient solution, there seems to be a chemical reaction that makes Magnesium raise the ph on your solution, i too had noticed the delayed change on PH levels, one solution was to only using RO water, because even-though my local tap water quality is pretty good, they add minerals that make water alkaline on purpose to kill bacteria. Those minerals buffer PH and takes more PH Down solution to bring it down. maybe even creating a PH Nutrient Lockout. so avoid all that fuzz and just use RO filtered water
I didn't write this myself but here's the best explanation I've found so far: Why is maintaining a stable pH so difficult? Three major factors tend to disrupt the stability of the pH in any hydroponic system. Learning to control these influences is essential for a successful harvest. pH imperfection #1: the pH of the water used to dilute nutrients Freshly distilled or deionized water has a pH of 7. However, the pH of the water may fall to as low as 5.5 within hours of preparation. This is because water absorbs carbon dioxide (CO2) from the air. The behavior of tap water is even more complex. It contains dissolved and slightly alkaline calcium and/or magnesium salts. In this case, absorption of CO2 from the air makes predicting the pH even more challenging. Because the calcium and magnesium salts in most tap waters, not to mention even more chemically complex well and spring waters, create such serious problems, many hydroponic growers, from hobbyists to huge commercial greenhouses, prefer using treated water. Although a number of water treatment systems exist, reverse-osmosis (RO) is considered the most economical. Water obtained from an RO system is almost as good as expensive distilled water. Another option is to adjust the pH of tap water before using it. This can be done with so-called pH up or pH down additives. However, this task is demanding and often done incorrectly-and what's worse, the acidic and alkaline chemicals used in these products, and the resulting sudden fluctuations in pH when they are added to the reservoir, can be hard on your plants. pH imperfection #2: biochemical processes in the nutrient solution Many pH changes are caused by the nutrients themselves. The more compounds in the water-measured in parts per million (ppm) or by the nutrient solution's electroconductivity (EC)-the greater their influence on pH. For example, the urea used in many fertilizers is broken down by enzymes into one molecule of CO2 (a slightly acidic compound) and two molecules of ammonia (a slightly alkaline compound). This can cause erratic changes in pH. In addition to urea, any compound containing an amide chemical bond (e.g., the proteinates used in many fertilizers) can, when broken down, affect the pH in unpredictable ways. Nutrient absorption also leads to changes in pH. When a plant absorbs a lot of potassium ions, it gives out hydrogen ions in return. The result is a net decrease in pH. The situation reverses when the plant absorbs a lot of nitrate ions and gives out hydroxyl ions to compensate, thus increasing the pH (Bar-Yosef, Ganmore-Neumann, Imas, and Kafkafi, 1997; Ryan, P.R. and Delhaize, E., 2001). The higher the rate of nutrient absorption, the more dramatic the change in pH. pH imperfection #3: the substrate through which the nutrient solution flows The growing medium (also called the substrate) affects pH as well. For example, coco-based growing media undergo subtle changes during your crop's life cycle that affect the pH of the nutrient solution. Even baked clay pellets, which are far more stable than coco coir in terms of pH, are less than rock solid in this regard. In fact, every chemical or biochemical process that goes on in the growing vessel changes the pH of the nutrient solution. Each additional factor drives it further from the sweet spot. In nature, the volume of surrounding soil-teeming with microbes, humates, and other pH stabilizing agents-does a good job of offsetting pH changes. Natural soils thus act as natural pH buffers. That's why, in outdoor gardens, where the soil itself contributes to a more stable pH, changes in pH are more gradual than in a hydroponic gardens.1 In hydroponics, however, pH stability is a challenge. It is an intense gardening method where the concentration of nutrients and their absorption rate by plants are much higher than in soil. As a result, chemical and biochemical processes influence the pH to a much higher degree than in natural soils or traditional agriculture. The natural stabilizers and buffers in the nutrient solution, mainly phosphates, are weak, so indoor gardeners have to check the pH of the nutrient solution regularly and adjust it when it goes below or above the sweet spot. What a hassle.
Runoff isnt relevant and should not be used as a gauge for ph... You need to buffer your water before the nutrients are added.. For example, before even mixing nutrients, ph your water by adding buffers to keep the ph more stable when the plant is pulling in nutrients resulting in rising ph..
Canna coco comes prewashed and buffered outta-the-bag..Just water/feed at your normal 5.8 pH and unless you actually see issues/probs don't worry about it as RR stated.. my2cents..
Yup! It's normal! I have always noticed that this happens! I adjust my solution to 5.5 because later that day it will adjust itself to around 5.8-6.0. Their are so many factors that play into this! One is when using an air stone. Using an air stone can gradually increase ph. Also mixing diff nutes can fight with each others ph buffering capacity causing the ph to change. Buffering capacity is the ability of a substance to hold it's ph. So a solution with a hi buffering capacity will be hard to change it's ph. Diff nutes have diff buffering capacities and can cause the solution to change ph over time. Sent from my iPhone using GC Forum
Exactly, my constituents are dead on when we advise 5.5 for coco... Especially if you buffer your tap water.. Great advice..
I agree with mike, when the solution is exposed to air there is a chemical change that the co2 and the o2 cause the PH to go up, Another factor no one has mentioned is the water that evaporates also contributes to PH change. I noticed that mixing the solution and then storing it on a sealed container reduced the PH change quite a bit.
Actually tap water is alkaline to protect pipes! Acidic water kills bacteria. City/tap water has chlorine added to it to kill bacteria! Tap water has to be in the 4.0 or lower range to kill bacteria. Saltwater in the ocean is alkaline and is full of bacteria and protozoans Sent from my iPhone using GC Forum
Id say its because K (the most abundant of the nutrients used in any mix usually for ppms sake), which would raise ph, and is also a cation represented as K+. Coco is an organic medium, cations attract this... Nh4 N for example is an anion, and is not going to remain in the medium... So you feed N levels like you do in reg hydro typically... You should buffer your water before you even think of adding nutes.. And I strongly recommend RO water so consistency is attainable.. Not saying CaCo3 (calcium carbonate) isnt the culprit, but if you buffer correctly, even with tap, you shouldnt have any issues.... CaCo3 is not exactly absorbable for the plant...
Not trying to create waves but I find this post a bit inaccurate. Some bacteria can live in sulfuric acid and some can handle chlorine which has an alkaline ph around 9 ish. In fact the only thing that I am aware of that can keep killing bacteria without the bacteria building a resistance over time is UV-C. Bacteria breeds at such a rapid rate that it can form a resistance to anything if given the chance. The hope with adding chlorine is to kill MOST deadly bacteria in city water. It was mentioned that O2 and CO2 can raise PH. CO2 when mixed into a solution creates what is called carbonic acid, and lowers the PH of a solution. Plant release CO2 from there roots, which aids in releasing ions such at calcium, iron and so on. I thought that would be a fun aspect to add. But yeah, does anyone know of a PH down that last awhile and doesn't drift?? Been using sulfuric acid from the pet store but it always goes up overnight!! I love the idea of brining it down to 5.5 that was something I was thinking and its nice to see that other people do that without negative results.
Actually that is not inaccurate at all! You proved exactly what was said! Acidic water does kill bacteria, and a level of acidity was not mentioned! And yes their are extremophiles that can handle the extremes but we aren't talking about the ocean or anything even close, we are talking about tap water! Look it up online, water is alkaline because acidic water damages pipes in the long run.
Actually I'm a paramrdical technician and we use water that has a ph of 4 to disinfect wounds and for cleaning and disinfecting, just pure water! And check this out! Most city tap water in the U.S and other countries is alkalized (OH added) to raise the pH to about 8.5 on average. This is because low pH water tends to dissolve things like concrete drain pipes and copper piping; while high pH tends to form deposits which actually thickens the same pipes. The reason is that thicker pipes rupture less often but plug over time.
I don't disagree with you on acid killing bacteria. It does but chlorine is alkaline and the post I was commenting on said that alkalinity does not kill bacteria but chlorine and acidity does. And maybe they do add chlorine which ha OH to also raise PH along with disinfecting but where I live, my state is mostly concerned with hardness of water fowling up pipes. Mainly it's the acid rain that leaches these minerals from the ground and into the water supply. Also our ground water is at a PH of around 8.5 while well water is at 6.5ish. The city I happen to live in gets its water supply from a lake and adds cholrine to disinfect not to save pipes. So yes I agree acidic conditions can kill bacteria, I was just trying to point out that alkalinity can also kill bacteria and not ALL bacteria is killed by either. Hence why I like to switch from vinegar to simply green on a weekly basis so if a bacterium forms a resistance to alkaline conditions than the acidic nature of vinegar mixed with some anti viral attributes should take care of them the following week. We'll that's the goal at least. I will say however, that it would make sense to lower PH to help curb the erosion of pipes and so on. But I can't imagine having much phosphoric acid ( an acid that erodes concrete) in drinking water. Depending on the source you may have a little sulfuric acid ( MOSTLY erodes organic compounds) and if it happens to have hydrofloric acid ( mostly erodes metals) or hydrofulric ( practically everything with the exceptions of number 2 plastics) then yeah I would be concered about ph in drinking water and would want it to be lower. But I won't disagree just wanted to point out that acid isn't the only thing that will kill bacteria nor does it kill all bacteria like the broad sweeping statement seemed to suggest. I guess I didn't make my point clear and maybe I misunderstood what was being written at the time I read it. Wouldn't be the first time I have done that. Or it may be due to my overly literal nature. I hope this comment doesn't seem like I'm trying to be a jerk of a smart as* I'm typing on an iPad and I tend to have to read what I wrote and correct things a few time since writing is not my forte. I have severe ADHD and scored so low in writing that at age 16 I had the writing ability of an 8 year old. I'm am, however very gifted in puzzles and mazes, along with having the commen knowledge of a 26 year old at 16. Anyways sorry for the confusion, maybe I'm at fault for that and thank you for pointing out that my statement was also board and sweeping.
And I have a environmental science major, so I do know a thing or two about water quality in the US since I had to write many lab reports (what a headache that was) on water quality testing and reporting using information from the EPA water quality section of there website along side some state data reports. Most of the contaminates seem to be non point sources which made it very hard to put things together in the end. With the exception of some methy mercury coming from tree left in the flood zones of the various hydro dams. And skin is ph of 5.5 so I bet 4.0 should kill most bacterium that could survive even on the surface of the skin. I am surprised though, I thought they used triple antibiotics or something similar to that. Thanks for the info though , kind of a fun fact to know!
Oh, sorry I forgot but our city water also along with being in the neighborhood of 8.5 to 9 ph we also are bless with having very soft water at EC us 100 or .1 while the well water which is still a bit acidic tends to be in between an EC in us (micro Siemens) 200 to 500. So with a ppm .5 conversion it comes in at 100 to 250ppm so it can be either hard or soft depending on where you live and since sulfuric acid doesn't tend to dissolve copper or PVP they could care less about the PH and more about the hardness clogging pipes in homes that have well water or town that get there city water from wells. And yes I am aware that OH in a solution makes the solution alkaline and Hydrogen ions in a solution makes it acidic. And the CO2 can also cause a solution to became acidic and is referred to as carbonic acid. O2 doesn't really effect PH that I am aware of but the capacity for water to hold O2 drops with raising water temps. Which is what happens when a lake gets to hot and fish get (heat stroke) from lack of O2.