(pics down below) If shitty cell phone pics are of value to anyone, I can document my ongoing grows which are all now done without pH adjustments. It wouldn't be the first thread of it's kind.
The total carbonates (alkalinity - i.e. acid buffering capacity) in my tap water don't go over 45 ppm and despite that the pH can rise to as high as 9.5 during the summer from a low of 7 in the winter, GH (or another brand with similar ammoniacal nitrogen content) nutes always mix to a 5.8 pH
First, an array of reputable sources on the subject of water pH, alkalinity and medium pH:
Fafard Grower FAQ
My water pH is very high. Will this affect the mix and the crops grown?
Water pH is a measure of solution acidity or basicity. It is an easy assumption that the pH of the irrigation water can affect the potting mix pH. However, water pH alone has little impact on the mix. Instead, another property of water, the alkalinity level, affects mix pH. High pH water can, but does not always, have high alkalinity and should prompt a complete water analysis to determine alkalinity level. Irrigation water high in alkalinity can induce rising growing mix pH, resulting in trace element deficiencies in pH sensitive crops like petunia and calibrachoa. Considered as a single factor, high water pH is a bigger factor when preparing pesticide solutions rather than its effect on the mix. Low pH water can also cause problems. The reduced bicarbonate concentration in low pH water can cause declining potting mix pH, increasing the potential for trace element toxicity problems in sensitive plants like geranium and marigold.
What is the pH of Fafard mix and how is it affected by plant culture?
Fafard mixes are limed so that two or three days after watering in, the pH will be between 5.5 and 6.5. However, the amount of lime in the mix is only one of several factors that affect media pH as the crop is grown. Water alkalinity level and type of fertilizer used also have a major influence on mix pH. Alkalinity, a measure of a water's ability to neutralize acid, is caused by the bicarbonate ion. Highly alkaline waters can cause mix pH to increase over time with high levels causing a greater degree of increase than lower levels. While moderately alkaline water may not change media pH, low alkalinity can actually cause mix pH to decrease. Water alkalinity levels can easily be determined through water analysis. Fertilizer also affects media pH. Fertilizer that contain ammonium or urea (20-20-20, for example) have an acidifying effect, causing a decrease in pH after repeated use. Fertilizers that contain little or no ammonium or urea (like 20-10-20) are not strong acidifiers. Some materials like 15-0-15 have a basic effect, resulting in a pH increase. The label of soluble fertilize bags will always show the material's potential acidity or potential basicity. This measure can be used to judge a fertilizer's potential to change growing-mix pH. With controlled release fertilizers, the potential acidity or basicity is not shown on the bag. If the fertilizer is formulated with ammonium or urea or is sulfur coated, the material will have an acidifying effect on mix pH. The amount of lime in the mix is not always the main factor controlling mix pH. Two other factors — the alkalinity of the irrigation water and the type and concentration of fertilizer used — also have a major influence on pH. When managing growing-mix pH, all three factors must be considered.
Irrigation Water Quality for Container-grown Plants
A measure of acidity or basicity. The pH of irrigation water can influence the pH of the root medium over time, especially in soilless
media, which in turn affects nutrient availability. Even though the water pH is important, the primary factor in how quickly irrigation water influences pH is the alkalinity of the water (see alkalinity below).
Water Quality: pH and Alkalinity
Recently, some growers have expressed concern about the "high pH" of their irrigation water and its potential adverse effects on plants. The purpose of this article is to allay some of these concerns by pointing out the difference between "high pH" and "high alkalinity".
Alkalinity and pH are two important factors in determining the suitability of water for irrigating plants. pH is a measure of the concentration of hydrogen ions (H+) in water or other liquids. In general, water for irrigation should have a pH b etween 5.0 and 7.0. Water with pH below 7.0 is termed "acidic" and water with pH above 7.0 is termed "basic"; pH 7.0 is "neutral". Sometimes the term "alkaline" is used instead of "basic" and often "alkaline" is confused with "alkalinity". Alkalinity is a measure of the water's ability to neutralize acidity. An alkalinity test measures the level of bicarbonates, carbonates, and hydroxides in water and test results are generally expressed as "ppm of calcium carbonate (CaCO3)". The desirable range f or irrigation water is 0 to 100 ppm calcium carbonate. Levels between 30 and 60 ppm are considered optimum for most plants.
Irrigation water tests should always include both pH and alkalinity tests. A pH test by itself is not an indication of alkalinity. Water with high alkalinity (i.e., high levels of bicarbonates or carbonates) always has a pH value ÷7 or above, but water with high pH doesn't always have high alkalinity. This is important because high alkalinity exerts the most significant effects on growing medium fertility and plant nutrition.
High pH and High Alkalinity Effects on Plant Nutrition
Potential adverse effects. In most cases irrigating with water having a "high pH" ( 7) causes no problems as long as the alkalinity is low. This water will probably have little effect on growing medium pH because it has little ability to neutralize acidity. This situation is typical for many growers using municipal water in Massachusetts, including water originating from the Quabbin Reservoir.
Of greater concern is the case where water having both high pH and high alkalinity is used for irrigation. In Massachusetts this situation is most common in Berkshire county. One result is that the pH of the growing medium may increase signifi cantly with time. This increase may be so large that normal lime rates must be reduced by as much as 50%. In effect the water acts as a dilute solution of limestone! The problem is most serious when plants are grown in small containers because small volum es of soil are poorly buffered to pH change. Therefore, the combination of high pH and high alkalinity is of particular concern in plug seedling trays. Trace element deficiencies and imbalances of calcium (Ca) and magnesium (Mg) can result from irrigating with high alkalinity water.
It is much more difficult to predict the effects of irrigating outdoor flower crops, gardens, and landscape plants with water having high pH and high alkalinity. On the one hand, in some parts of the United States, long-term irrigation of crops with wa ter high in bicarbonates and carbonates has led to yield-limiting trace element deficiencies which must be corrected with special fertilizers. On the other hand, in New England, several factors probably act together to partially offset the effects of high alkalinity water. First, rainfall levels are relatively high and historically this has caused Ca and Mg ions to leach from the soil. These are replaced with H+ and the result is acidic soil. Second, this acidification may be helped along by the rather ac idic rainfall common in this region in more recent times. Third, acid-forming fertilizers also help counteract high pH and alkalinity.
Understanding Plant Nutrition: Irrigation Water Alkalinity & pH
Agro and Fisher take a microscope to the details that can help growers make informed decisions on nutrients.
By Bill Argo and Paul Fisher
Water Alkalinity Has A Big Effect On Substrate pH
When it comes to managing the pH of a substrate, the alkalinity concentration has a much greater effect than does water pH. Alkalinity (calcium bicarbonate, magnesium bicarbonate and sodium bicarbonate) and limestone (calcium and magnesium carbonate) react similarly to limestone when added to a container media. And just like too much limestone, the use of irrigation water containing high levels of alkalinity can cause the pH of the substrate to increase above acceptable levels for healthy plant growth.
For example, a limestone incorporation rate of 5 pounds per cubic yard will supply approximately 100 mEq of limestone per 6-inch (15-cm) pot. Applying 16 fluid ounces (0.5 liters) of water containing 250 ppm alkalinity to that 6-inch pot will supply about 2.5 mEq of lime. That does not sound like much until you consider that after 10 irrigations, you have effectively increased the limestone incorporation rate by 25 percent.
To compare the effect of water pH or alkalinity on the ability to raise pH (or neutralize acid) in a medium, 50 ppm alkalinity (which is a low alkalinity) would be similar to having a water with pH 11 (i.e. an extremely high pH). A water with a pH of 8.0 would have the same effect on substrate pH as an alkalinity concentration of only 0.05 ppm (i.e., almost nothing).
Don’t ignore water pH, though. Water pH is still important for crop management because it affects the solubility of fertilizers and the efficacy of insecticides and fungicides before you apply it to the crop (Figure 2). Generally, the higher the water pH, the lower the solubility of these materials.
ALKALINITY CONTROL FOR IRRIGATION WATER USED IN GREENHOUSES
Preventing pH changes will eliminate many of the nutrient problems encountered in bedding plant production. Unfortunately, there are many forces at work that affect substrate pH, and maintaining a constant pH is no easy task. There are four major forces that affect the substrate solution pH during plant production: preplant materials such as dolomitic limestone put into the substrate and the substrate components themselves; · the alkalinity of the irrigation water; ¸ the acidity / basicity of the fertilizers used during production; and ¹ the plant species being grown.
Australian Blue - the Blue Haze pheno x 3 ladies. All are just about three feet tall, so I dropped the bulb down so the top of it is even with the top of the slightly tallest plant. They undertook a four week CFL veg period from rooted clone to about 18" tall, than another week of "veg time (20:4)" using the 600w vertical HPS to 24" tall. They were being hand fed twice a day over the last few days, but even that wasn't enough for the 1.5 gallon containers. The drip system was put in place last night in time with the first full-on bloom rez being mixed. It will be interesting to see if any difference in the structure of the roots in the square pot vs the round pot, because everything else has been equal. today is day 12 of bloom:
#1 and #3 inside the bloom room:
Unknown x 1 - forced into flowering because of hermie issues and I wanted the room to be full:
Bloom group shot:
this is how I hang the bulb:
Nutrient starting points:
Full strength Veg - 3 ml / gallon FNG & 1/2 ml / gallon G.O. CaMg+ & 1 gram epsom
Full strength Bloom - 4 ml / gallon FNB & 1/2 ml / gallon G.O. CaMg+ & 1 gram epsom
EC: 1.3 (tap water EC .2)
Seedlings and cuttings - 1/2 strength veg + 5 ml gallon Neptune's Harvest Benefits of Seaweed
Bubble cloner - 5 ml gallon Neptune's Harvest BoS - this water is pH adjusted of course
Bloom Ballast: NextGen 600w HPS
Bloom Bulb: SunMaster 600w HPS
Veg: 200w CFL ghetto style DIY array
next generation grow: The ol' Blueberry Haze from DNA genetics
For these ladies, I will be adding two more vertical lights, another 600w HPS and a 1k HPS. In a few days I'll be harvesting 1 plant from a small closet (shoulda been two - hermie problems) and converting that into a veg area.