Here are some definitions and abbreviations.
Carbon Dioxide (CO2)
Hydrogen Peroxide (H2O2)
DO: Dissolved Oxygen, A measure of the amount of oxygen in suspension in a nutrient solution.
RO: Reverse Osmosis, Water that has been forced through a very solid membrane to remove suspended particles.
H2o2: 35% Hydrogen peroxide.Max dose = 2.5ml/gl
HID: High Intensity Discharge, HID lights fixtures include MH and HPS
HPS: High Pressure Sodium light
MH: Metal Halide light
Conversion bulb: A bulb designed to convert a mh to hps or visa/versa
Rez level: the top of the nutrient solution in your rez, always maintained at a specific volume marked in your rez, or with a sight tube. It is very important to make sure your rez is it at the full level mark before
you measure ph or ppm.
nutes: Chemicals designed for hydroponic growth.
nute load: The max amount of nutrients reccommended by a nute mfg,
expressed as a percentage. He is using a 50% nute load.
solution: a mixture of hydroponic nutes.
ph: a measure of the hydrogen ions available in your nute solution.
Buffer: A chemical suspended in your water that acts like a sponge to absorb acids, in tapwter it will be Calcium-carbonate. If you use RO, then you can use Potassium molecules for buffering, without the damage caused by excess Ca.
tds: Total Dissolved Solids, a measure of some
the suspended chemicals in your nutrient solution.
ppm: Parts Per Million, a number representing the tds in your nute solution.
EC: Electro conductivity, a measure of the salts in your nutrient solution. tds, ppm and ec are all the same measurement, just expressed in different values.
AN: Advanced Nutrients, a company that mfg nutes.
DM: Dutch Master, another nute mfg
GH: General Hydroponics, another mfg.
CM+: cal mag plus is an additive made by Botanicare.
LL: Liquid Light, a foliar spray made by DM
MET: Mother Earth Tea,
Organic hydro nutes, grow and bloom, by AN
Conni: Connoisseur, a bloom nute by AN
Grow medium: A method to establish the sprout,
the method used to hold the plant in the water.
Ususally Coco Coir plugs and Hydroton Clay pellets,
Neopreme plugs, or Rockwool.
ml: metric measurement Milliliter.
L: Metric measurement of Liters
g/gl: US measurement, Gallons
g/gr: Metric measurement, grams
VPD: vapor pressure deficit
Power head: A pump used in aquariums to increase DO
Air pump: Another tool used for increasing DO
1. You must purchase an accurate ph meter
before you plant your first seed.
2. If you choose to grow without a ppm meter,
you must carefully follow the nute mfg directions,
to avoid nutrient burn, and you should use a reduced nute load.
3. Your rez should have a drain system with a pump,
to make nute changes fast and easy.
This will save a lot of time and spills, and pay off greatly.
4. If you grow with tap water,
you should reduce the nute load by 50%.
5. Use RO water, unless you have very low ppm tap water.
6. Use these two rules to determine when to change your rez.
a. The Add back
b. The pH
7. Low ppm nute solutions are easy to correct, but even slightly high nute solutions can cause irrepairable damage. Nute Mfg test their chemicals using commercial RO machines(000ppm), and very controlled temperature and humidity. Always use less nutes(chemicals) unless you are able to copy the nute mfg environment exactly.
8. 3.5-5gl/plant, is a good rule of thumb for estimating efficient rez volumes.
9. Start your seed in the medium you are going to grow in. All seed companies recommend this practice. Use the best genetics you can find.
10. Seeds can live on the stored energy they are sprouted with for 10 days. Don't feed new sprouts for at least 7 days, and then you should only use 1/4 strength nute solutions for the first week.
11. Always completely change out the solution with fresh water,
and then add new nutes.
12. Never adjust the pH of the water before you add it to the solution. Pre adjusted pH'ed water will not be stable. Add clean water to top off your rez, and then measure the pH, then adjust the pH.
13. Don't burn the flavor out of your plants with HID lights. Sure more light equals faster growing, but why would you want to quickly grow hay? Use lights close during veg and move them further away in flower. Strong evidence supports the use of UVb lights to increase potency.
14. Buy a 60 to 100 power pocket microscope. You can see bugs, their eggs and, near harvest time, you can check trichomes.
15. Use Bed lice spray from the drug store to aggressively attack spider mites. Permethrins will cause the eggs to destruct. Spray under the leaves to kill the eggs. There will be no residue from this product because it breaks down with uv light.
16. If you use RO water, AN Barricade is an excellent limited buffer with a very small dose. Do not exceed Barricade's recommended application rate. Use an eye dropper to deliver Barricade, and check the pH between each drop. Barricade will raise the pH.
17. Use metric calibrated eye droppers, syringes, and baby medicine spoons, for very accurate dosing of nutes, and for ph adjustment.
18. Too low humidity can cause VPD.
19. Insulate, shade, or isolate your rez from light, and heat. Air blowing over the surface of your rez, will reduce the temp by 7-10º.
20. A fan to move air over the plant is required.
21. Have a power head in the bottom of your rez to keep the solution moving all the time, along with your air pump.
22. Uncontrollable pH swings can indicate a diseased root system.
If your pH is falling to 3 or 4, this would be a good indicator of advanced root rot.
23. The max dose for 35% H2o2 is 2.5ml/gl.
24. Control is what gives hydro the growing edge. Control results in better flavor, faster production, and higher yields. You can control the water, the air, the temperatures(rez & air), the humidity, the nutes, the ph, and the light.
Here is the Add Back & pH rule.
It is important to follow these two rules until you have completed a full grow,
and they are especially important if you are not using a tds meter.
1. The Add Back Rule
: Once you have replenished the original rez volume with fresh water, then it is time to change out the rez with fresh water and new nutes.
Never add nutes between nute changes,
until you have experience with the nutrients you are using,
and then you must
have a tds meter.
Add fresh water once or twice a day to maintain the rez volume.
Do not adjust the pH before adding water to the rez.
Most of the time you will find that adding fresh water to top off the rez, will bring the pH back to normal range.
Check the pH and adjust if necessary, after
adding water to top off the rez.
If you have a 5 gl rez, and you have added 5 gl over the last few days to maintain the rez level at the full mark, then it is time for a complete change out.
Keep and re-fill your plastic jugs to help maintain your add back count.
2. The pH Rule
There are separate pH rules for RO and tap water.
We will discuss RO first.
With RO, you will control the buffers.
There are three chemicals
that will allow you to get a stablized nute solution
without causing any nutrient lockout.
First you need to get some AN Barricade
which is Potassium Silicate.
You should also get some Potassium Carbonate,
and Potassium Hydroxide.
I buy these two chemicals premixed
in the powdered form from GH,
and then add RO to make a solution,
which I use to increase the pH with my eye dropper.
So here is the drill.
Add the nutes and any additives you are using,
and then measure the pH. (do not add Barricade until the pH falls below 5.6)
Most of the time the ph will be around 5.6
right after you add the nutes.
In a few hours check the pH
and it will be down as the buffer is overcome.
(I let it go down until 5.2-5.4
and then add Barricade to bring the pH up to 5.6).
Add one drop of barricade per gl,
and then check the pH.
( you need an eyedropper)
Keep using Barricade to bring the pH back to 5.6
until you have reached the max dose of .5ml/gl
(5 drops/gl of barricade max)
After you have maxed out the barricade,
then the next time the pH falls,
start using the GH Potassium Carbonate/Hydroxide powder in RO solution,
to bring the pH back up to 5.6
and after a couple of days the pH will stop moving.
You will have the solution buffered
with these three potassium molecules
and can reach a perfectly stable equilibrium.
When you add nutes to RO water, the nutes alone will probably lower the ph to around 5.6
If the ph drops below 5.6 after you have added new nutes to RO water,
use .1ml/gl Barricade to buffer the ph back up to 5.6.
Solutions with RO or distilled water
will require the use of an eye dropper to maintain pH.
Measure pH between each drop,
until you are familiar with your solutions requirements.
These are the pH rules for tapwater
or water over 50ppm and/or initial pH of near 8.
After you add nutes to your water,
the pH should be close to 5.6.
If your water is very hard, over 200ppm,
then you will need to add pH down
(Phosphoric acid, or Nitric acid)
to achieve 5.6.
In a few hours,
as the buffers absorbs the acids,
the pH will move up,
back to near the original pH of the water.
So, you will need to continue to add pH down,
at least twice a day,
to re-establish the pH back at 5.6
After doing this for a few days,
the pH will become stable for a few hours,
maybe even for a day or so,
and then the pH will fall
below 5.6 without adding any pH down. When the pH falls without you adding pH down,
you have met the pH rule.
This is when it is time to change the nutes,
even if you have not met the Add Back Rule
For some nutes,
it is best if you always let the pH move from low to high,
and then you adjust it back down,
while other nutes will react in the opposite way,
depending on whether the mfg decided to buffer the formula or not.
Try to never allow the pH lower than 5.2 or higher than 6.2,
ideally you will maintain 5.6,
but in reality you will probably drift between 5.2 and 6.0
The time that this sequence takes will vary with the plant size,
the amount of water the plant is consuming/transpiring,
and the concentrtation of the nute solution (ppm/nute load).If you are growing with tapwater,
the pH rule is the best method to determine when to change the nutes.
It can be as long as 10 days, and as short as 4 days.
If you must use tapwater,
It is highly recommended to use a Hard Water
Your rez volume, the phase of your grow, and the type of nutes you have
will determine how often you need to adjust the pH.
Your job is to maintain the pH,
and change out the nutes at the appropriate time.
Here is some info about water.
This is "good to know" info since this is our main growing medium,
and will help you understand why the pH changes.
Water has very unique density qualities.
Most liquids become denser as they become cooler.
Water, however, gets denser as it cools
until it reaches a temperature of approximately 39ºF.
As it cools below this point, it becomes lighter until it freezes (32ºF).
As ice develops, water increases in volume by 11 percent.
The increase in volume allows ice to float rather than sink,
a characteristic that prevents ponds from freezing solid.
Being a "universal solvent," as it is sometimes called,
water can dissolve more substances than any other liquid.
Over 50 percent of the known chemical elements have been found in natural waters,
and it is probable that traces of most other elements can be found in lakes, streams, estuaries, or oceans.
Dissolved gases are those which are in a water solution.
An example of gas dissolved in solution is soda water
which has large quantities of dissolved carbon dioxide.
The most common gases are oxygen, carbon dioxide,
nitrogen, and ammonia.
Concentrations are measured in parts per million (ppm)
or milligrams per liter (mg/1), both units of measure are the same.
Dissolved oxygen (DO) is by far the most important chemical parameter.
The amount of oxygen that can be dissolved in water decreases
at higher altiitudes.
At sea level and zero salinity,
that means no nutes, 68ºF water can hold 9.2 ppm DO,
while at 86.0F, saturation is at 7.6 ppm DO,
and unable to support "useful" life.(you can grow bacteria)
In combining this relationship of decreased solubility with increasing temperatures,
it can be seen why oxygen depletion are so common when higher water temperatures occur.
If you live in Denver, then you will really suffer low DO at high water temps.
After you add nutes(salts), then you further decrease DO.
This is another reason why lower nutes loads are better, most of the time.
Now let's take a look at pH.
Pure water is neutral and has a pH of 7.0.
Pure water consists of H20 molecules
surrounded by a relatively small number of Hydrogen ions
and Hydroxide ions (H+ and
Pure water is considered neutral because it has an equal number of
H+ and OH- that are freely available for chemical reaction.
Pure water has a pH of 7.0 because it contains 10-7 moles of H+ per liter and the
negative logarithm of 10-7 is 7.0.
The water coming from my RO machine is 6.5pH and 022ppm
Adding acids or bases to water changes its pH.
The pH of a sample of water is a measure of the concentration of hydrogen ions. The term pH was derived from the manner in which the hydrogen ion concentration is calculated -
it is the negative logarithm of the hydrogen ion (H+) concentration.
What this means to those of us who are not mathematicians is
that at higher pH, there are fewer free hydrogen ions,
and that a change of one pH unit reflects a tenfold change in the concentrations of the hydrogen ion.
For example, there are 10 times as many hydrogen ions available at a pH of 7 than at a pH of 8.
This means a pH value below 7 is ten times more acidic than the next higher value.
For example, a pH of 4 is ten times more acidic than a pH of 5
and a hundred times (10 X 10) more acidic than a pH of 6.
This holds true for pH values above 7,
each of which is ten times more basic (also called alkaline) than the next lower whole value.
An example would be, a pH of 10 is ten times more alkaline than a pH of 9.
The pH Scale...
The pH of water determines the solubility (amount of salts that can be dissolved in the water) and biological availability (amount that can be utilized by aquatic life) of chemical constituents such as nutrients (phosphorus, nitrogen, and carbon) and heavy metals (lead, copper, cadmium, etc.). For example, in addition to affecting how much and what form of phosphorus is most abundant in the water, pH may also determine whether aquatic life can use it. In the case of heavy metals, the degree to which they are soluble determines their toxicity. Metals tend to be more toxic at lower pH because they are more soluble.
How temperature effects pH.
When temperature changes, the actual pH of the solution being measured changes. This change is not an error caused by the change in temperature. It is the true pH of the solution at the new temperature. Since this is not an error, there is no need to correct or compensate for this temperature effect.
This temperature error is very close to 0.003 pH/oC/pH unit away from pH7. In a perfect pH electrode - one that is zeroed at exactly pH 7 - there is no temperature effect on the electrode sensitivity at pH 7 no matter how much the temperature changes. Most pH electrodes are not perfect, but the errors from changes in temperature are still very minute when near pH 7, plus or minus one-tenths of a pH, and can be disregarded. However, the further from pH 7 the solution is and the greater the temperature changes, the greater the measurement error due to changes in the electrode's sensitivity.
These errors come from changes in electrode sensitivity due to changes in temperature, and can be corrected by meters with temperature compensation. Most pH pens are not temperature compensated.
Odd as it may seem, despite being one of the most well known substances in the world, even today it's still widely studied by scientists, and there are many new properties still being discovered. One of its well known, but very interesting properties, is water's ability to dissolve into itself.
What?!?!? That's right...just as when you add common table salt (NaCl) to pure water, which quickly breaks the Na-Cl bond and dissolves it into Na+ and Cl- (called ions), when you "add pure water" (H2O) to pure water, part of it dissolves into H+ and OH-. The main difference is that, while with salt you can add several spoons into a glass and virtually all of it gets dissolved, only a very small amount of pure water gets dissolved into water.How much? Well, at room temperature, about 1 molecule in every 10 million (10to the7th power) is dissolved. This means that, in a typical swimming pool full of pure water, only a few teaspoons of water would be dissolved. Now, that little number 7 up there near the 10 looks familiar, doesn't it? That's because it's exactly the number used to define "neutral pH". Note that, since each dissolved molecule of H2O results in 1 ion H+ and 1 ion OH-, these two ions are in equal amounts in pure water. The term "neutral" here means just that: the same amount of H+ and OH- ions. As mentioned above, at room temperature there's about 1 of each for every 107 molecules of water, and therefore we say that neutral water has pH=7.
And what about non-neutral water? If for any reason, the relative amount of H+ and OH- ions changes, then the water begins to drift from neutrality. If the amount of H+ ions increases, the water becomes acid, if the amount of OH- ions increases, the water becomes alkaline. For instance, suppose that the amount of H+ becomes 10 times greater than in pure water. Then there'll be about 1 H+ ion for every 1 million molecules of water (106) and therefore this water will have pH=6. Note that a change in 1 point in pH represents an increase of 10 times in the amount of H+ ions (in math this is known as a logarithmic scale). Since the amount of H+ never goes below 1 in 107 (at room temperature), the pH value for acid water will always be between 0 and 7. The value pH=0 means that there's 1 H+ ion for every molecule of water (1=100).
The same idea is used to represent increases in OH- ions. There's another scale used for this ion, called pOH, which works exactly the same: if the amount of OH- becomes 10 times greater than in pure water, then the new water will have pOH=6. For the same reasons explained above, the pOH values will always be between 0 and 7.
But using 2 scales complicates things unnecessarily, so it's more common to put both of them together in a single scale - pH. Now, instead of going only from 0 to 7, it goes from 0 to 14. The first half (0 to 7, or more accurately 7 to 0) represents increases in H+ (acid water). The second half (7 to 14) represents the increases in OH- (alkaline water). So, if you take pure water and increase the amount of OH- 10 times, the pH will raise from 7 to 8.
"Alkalinity and pH are distinctly different from each other, although their definitions and functions can be easily confused.
Alkalinity is essentially a measurement of water's ability to neutralize acids. It is a measure of the buffering capacity of a system while pH is basically the measurement of the concentration of hydrogen ions in water, in terms of acidity or alkalinity.
The alkalinity of water regarding pH issues merely refers to the basic end of a pH scale (alkaline) in contrast to the acidic end of the scale and does not reflect the buffering capacity of a system.
It is easy to believe that water with alkaline pH is likely to be high in alkalinity (buffering capacity). However, this is not necessarily true. Water with a high pH, but a low alkalinity is regarded as unstable.
Buffering capacity refers to water's ability to keep the pH stable as acids or bases are added.
pH and buffering capacity are intertwined with one another; although one might think that adding equal volumes of an acid and neutral water would result in a pH halfway in between, this rarely happens in practice.
If the water has sufficient buffering capacity, the buffering capacity can absorb and neutralize the added acid without significantly changing the pH. Conceptually, a buffer acts somewhat like a large sponge. As more acid is added, the ``sponge'' absorbs the acid without changing the pH much. The "sponge's'' capacity is limited however; once the buffering capacity is used up, the pH changes more rapidly as acids are added. Using the pH rule, we will change out the nute solution when the buffering capacity is used up
The presence of calcium carbonate or other compounds such as magnesium carbonate contribute carbonate ions to the buffering system. Alkalinity is often related to hardness because the main source of alkalinity is usually from carbonate rocks (limestone) which are mostly CaCO3. Since hard water contains metal carbonates (mostly CaCO3) it is high in alkalinity. Conversely, unless carbonate is associated with sodium or potassium which don't contribute to hardness, soft water usually has low alkalinity and little buffering capacity. So, generally, soft water is much more susceptible to fluctuations in pH.
The big problem with using tap water is the calcium/magesium ratio will be out of balance because there will always be more calcium carbonate in tap water than there is magnesium.
You can use hard water nutes, or add CAL MAG Plus to try to increase the ratio.
Dutch Master is supposedly making a new nute calculator
that will factor in your tap water ppm.
General Hydroponics makes a "Hard Water micro"
designed to be used with tap water.
If you must use tap water,
then you should ony use a 50% nute load.
Buffering has both positive and negative consequences. On the plus side, the nitrogen cycle produces nitric acid (nitrate). Without buffering, your tank's pH would drop over time (a bad thing). With sufficient buffering, the pH stays stable (a good thing). On the negative side, hard tap water often almost always has a large buffering capacity. If the pH of the water is too high for your plants, the buffering capacity makes it difficult to lower the pH to a more appropriate value. Attempts to stabilize the pH of tap water usually fail, because the buffering effects are ignored.
Bicarbonate (HCO3-) and carbonate (CO32-) are the most important ions that determine alkalinity.
When the carbonates accumulate in a growing medium, the growing medium solution pH reaches levels that cause plant growth inhibition, which is caused primarily by the transformation of soluble forms of Fe(iron) into insoluble forms.
Early investigations in plant nutrition demonstrated that normal plant growth can be achieved by immersing the roots of a plant in a water solution containing salts of Nitrogen (N), Phosphorous (P), Sulfur (S), Potassium (K), Calcium (Ca), and Magnesium (Mg). Hydrogen (H), Oxygen (O), and Carbon (C) are all derived from the air and water. These nine elements are defined as the macronutrients.
With further refinement in laboratory techniques, scientists established seven elements required by plants in relatively small quantities- the micronutrients or trace elements. These include Iron (Fe), Chlorine (Cl), Manganese (Mn), Boron (B), Zinc (Zn), Copper (Cu), and Molybdenum (Mo).
All plants require the same 16 chemical elements to grow
People use the word "chemical" as if they should be cautious about these materials.
The fact is, water is a chemical.
Everything has chemical properties.
The materials used for hydroponics
are no different from what you have used traditionally in your outdoor garden,
just in a different original(chelated) form,
and separated from the ground.
Organic growing requires living microbes
to turn the fertilizer into the chemicals that the plant can use.
In the end,
the chemicals that the plant can use use at the root zone,
are exactly the same,
whether they come from a microbes digestive tract,
or a test tube.
See how easy this is going to be now!
Show your grow,
these are just my opinions, from my experience to date. My opinions have been known to change. There may be some tips that will not apply to the way you are growing Hydro
since my only experience is with DWC and AERO. Hempy buckets and Bio buckets may use different pH.
Most hydro nute mfg reccomend 5.6pH