CF and PH levels, And troubleshooting plant problems.
CF and PH levels, And troubleshooting plant problems.
Ok here is a bit on PH etc, this includes charts and recomended levels.
What is pH?
pH is a scale from 1 to 14 that measures acid-to-alkaline balance. One is the most acidic, 7 is neutral and 14 is most alkaline. Every full point change in pH signifies a 10-fold increase or decrease in acidity or alkalinity. For example, soil or water with a pH of 5 is 10 times more acid than water or soil with a pH of 6. Water with a pH of 5 is 100 times more acidic than water with a pH of 7. With a 10-fold difference between each point on the scale, accurate measurement and control is essential to a strong healthy garden.
Cannabis grows best in soil with a pH from 6.5 7. Within this range, marijuana can properly absorb and process available nutrients most efficiently. If the pH is too low (acidic), acid salts bind nutrients chemically, and the roots are unable to absorb them. An alkaline soil with a high pH causes nutrients to become unavailable. Toxic salt build up that limits water intake by roots also becomes a problem. Hydroponic solutions perform best in a pH range a little lower than for soil. The ideal pH range for hydroponics is from 5.8 6.8. Some growers run the pH at lower levels and report no problems with nutrient uptake.
Ok this is a chart that shows you the right levels for soil and for Hydro.
Note that these are different to each other and also treated differently.
Method for Adjusting Nutrient Tanks
This is the correct order.
Top up your tank with water first
Test your nutrient strength
Raise the strength by adding equal amounts of A and B if necessary.
Now test pH
Adjust pH with pH Raise or pH Lower. Dilute* the pH adjustment solutions as directed on the labels.
* Concentrated adjusters are so acidic or alkaline that if used in a concentrate there will be a reaction with the nutrients dissolved in the tank. This can imbalance your highly formulated nutrient.
f testing both Nutrient Strength and pH, the nutrients are still best changed each week. However, Nutrients need only to be changed on a fortnightly to four weekly basis if desired.
The more often you change your nutrients, the more 'balanced' your solution will be. But as you will be adding nutrient as you go, the nutrient balance does not become as critical as it does without adjustments.
For pH control you will need pH liquid dropper kit, $10, pH test tape (1mtr $10, 5mtr $40) or a Waterproof pHScan1 meter $110, pH Raise $7.50 and pH Lower $7.50.
For Nutrient Strength control, a waterproof CF truncheon meter is $135.
It is recommended to get a waterproof meter as they won't corrode inside from the humidity around the tanks.
A simple lesson on meters
If price is a stumbling block, then don't buy any. Use our dump and change system outlined above. It's the best way to avoid problems.
Too many times we have heard of growers stories of the evils of buying cheap meters.
For instance, a meter might tell you the pH is 7.0 You adjust it down to pH 6.0. However, the cheap meter made an error, and it was actually 6.1 pH. Now you've adjusted it too far. The plants are sick, so you bring a sample to our store and have it tested. Its actually 5.1 ph. Aha you think and try to get a warranty on you cheap meter, which goes off and comes back again a week later, with the test saying, Calibrated OK. But you don't want to have that meter back, and you yell and scream that it made your plants sick! In the end, you have to buy a good one, or use none at all.
First lesson: buy cheap, buy twice.
Second lesson: If the plants look alright, they probably are. If they look sick, don't trust the meter automatically. Look for a reason and ask for advice. That's how to learn.
Note on reliability
We have tested expensive meters, and cheap meters.
pH meters need to be checked as the calibration can go out, but overall, any pH meter under $100 usually gives us a high return for failures. More expensive meters have longer lasting probes, however the pHScan1 WP has a probe that can be serviced (unlike most expensive meters) and has a replacement probe priced at $50 which is very cheap. I have reservations with the more expensive meters being less than completely waterproof, as humidity in Queensland and in growing areas generally can corrode the internal circuits of electronic equipment.
CF testers can be alright under $100 but can have a problem or two. The CF Truncheon has the same probe they use on the $3000 dosatronic computerized Nutrient dosing system. It's the best seller in Australia, New Zealand and USA. There is no advantage to being more accurate, or spending more money. In fact, spending more money usually involves stepping away from waterproof meters and since growing areas have high humidity, I think this is a mistake. I have two $600 meters that I just don't trust because of corrosion over time.
electronic testers will need to be checked and adjusted for accuracy every week. A calibration solution is essential to test your meter - however, when you buy your meter, the meter should be tested for you so you can learn how to do this. Replace your solutions regularly. pH 7.00 solution 250ml is $5.00, and CF 27.7 250ml is $5.00 also
CF - Part Two
Advanced Plant Control through CF (Conductivity Flow) control
Osmosis is the theory behind nutrient uptake from the roots. If we take a nutrient strength of say 22CF, the concentration would be roughly 99.86% water and 0.14% minerals. However, in a plants root system, there may be a concentration of up to 70CF.
Because there is a higher concentration of minerals and therefore a lower content of water in the roots, the water from the solution moves through the membrane-covering that the roots have, taking the minerals in our nutrient solution with it.
It doesn't actually happen that way. Experts now tell us there are specialized receptacles for certain minerals, but even the experts are not sure how the roots really work. This is a convenient way to explain how nutrient strength works.
If the concentration of nutrient is increased, the water content decreases, but by minute amounts. The difference between concentrations in the roots and in the solution is now closer, and nutrient solution is absorbed through the membrane more slowly. The effect on growth is exactly as you might assume.
The higher the CF strength the slower the new growth of the plant.
Higher CF = slower
The Lower the CF the faster the new growth of the plant.
Lower CF = faster
This would be, in the case of Tomatoes, a change from 24CF to 30CF or 0.156% to 0.195% nutrients. You cannot adjust a solution that accurately without a CF meter.
Also, due to the concentration then changing inside the plant, the emphasis on the type of growth changes.
Stem growth is more woody and usually thicker, the higher the concentration.
Leaf growth has more emphasis when the nutrient strength is low
Flower/Fruit Production has more emphasis when the nutrient strength is high
Height is determined in plants by the internodal length, or the distance before another branch or leaf occurs. The Internodal length is closer (plants are shorter and bushier) when the strength is high.
Calcium is a difficult element in terms of nutrient strength. While Nitrogen and other elements can be moved by the plant from the older leaves to newer leaves if required, calcium cannot be stored or moved. It must be available to the new growth at all times or calcium deficiency, characterized by tip burn of the leaves and blossom end rot on fruit, will occur. If the nutrients are not being taken up at a fast enough rate, the leaves will begin to brown at the tips. This occurs because the nutrient strength is too high and the nutrient uptake has been slowed by the high strength. If nutrient salts are building up in a Perlite, Expanded Clay, Rockwool or other media System, the plants roots are in the same situation of high nutrient strength. When adjusting CF levels with a crop, immediately check your strength if tip burn occurs.
Plant Troubleshooting Guide-
he most common problems are: over watering & over fertilizing, followed closely by an incorrect pH & root bound. ****Before ANY corrective steps are taken these factors MUST be ruled out.****
Nutrient Deficiencies - Nutrient deficiencies in modern gardens are really rare. What most people see as a â€˜Nutrient Deficiency' is, 9 times out of 10, a pH problem. A pH that is too high or too low â€˜locks out' your plants ability to uptake nutrients. Since the plant can not uptake those nutrients they appear to be deficient. When in fact, there are plenty of nutrients in the solution/soil but, due to pH Lock-out, they are unavailable to the plant. Adding supplements or more nutrients (which is what most do) will only compound this problem by throwing the pH off even more and further raising the nutrient/soil PPM. The best thing to do if you suspect ANY form of nutrient deficiency is to check and adjust the pH as necessary. The proper pH ranges for both hydroponics & soil is shown in the chart below. Pay particular attention to the ranges that certain nutrients are available and when they are locked out.
Solution - Adjust the pH to the correct range for your type of grow. Hydroponics = 6.1 to 5.5 & Dirt = 6.8 to 6.3
Over Watering - Signs of over watering include: Leaf wilting/drooping and Chlorosis (Leaf Yellowing). Also, smelly soggy soil is another indication in soil gardens.
Solution - Increase the temperature and airflow to evaporate some of the excess water. Also, you can add some h2o2 when watering to help the roots still receive O2. And just don't water as much. You should only water when your soil/medium is dry. If you have smelly soggy soil the best thing to do is transplant it into fresh dry soil.
Over Fertilizing - Signs of over fertilization include: dead/burnt leaf tips/margins and leaves curling under.
Solution - Check and adjust the pH level as necessary. Flush and decrease the fertilizer/nutrient level.
pH Problems - pH problems can manifest it self in many different ways. Anywhere from: nutrient deficiencies to over fertilization and leaf burn. The key to telling which you have is, knowing your pH.
Solution - Check and adjust the pH level as necessary.
Root Bound -Root bound is where the roots of your plant outgrow the container they are potted in. Plants that are root bound exhibit stunted growth, stretching, smaller and slower bud production, easier to burn with nutrient solution, needs watering too often, and wilting. A root bound plant will always start yellowing with the bottom leaves and work its way up the plant until all the fan leaves are gone.
Solution - See root bound below in the Root Problems section.
Heat Stress - Signs of heat stress can look a lot like nutrient burn, except it occurs only on the top of the plant closest to the lamps. A yellowing of the upper leaves is usually a bleaching from being too close to HID lights.
Solution - A good test to see if your lights are too close is to put your hand between the light and the plant. If your hand gets too hot for comfort, the light is too close and needs to be moved up higher.
Yellowing (Chlorosis) - Chlorosis is a yellowing of leaf tissue due to a lack of chlorophyll. Possible causes of chlorosis include poor drainage, damaged roots, compacted roots (see Root Bound below), high alkalinity, and nutrient deficiencies. Nutrient deficiencies may occur because there is an insufficient amount in the soil or because the nutrients are unavailable due to a high pH. **Note- Always check the pH before increasing nutrient level. In the last few weeks of flowering a yellowing of the leaves is completely normal as the plant uses up all stored nutrients.
Yellowing - Lower/Middle Leaves - Yellowing of the lower leaves/older growth is a sign of a possible Nitrogen (N) deficiency. Nitrogen is a transferable element (this means the plant can move it around as needed). If a plant is not receiving enough Nitrogen from the roots then it will rob Nitrogen from the older growth. Plants that are Nitrogen deficient will exhibit a lack of vigor and grow slowly resulting in a weak and stunted plant that is significantly reduced in quality and yield. In a Hydroponic system, usually the pH is too high and has locked out the available Nitrogen. In soil a yellowing of the lower leaves could also be an indication of a root bound plant (see Root Bound below).
Solution - First, check the pH, and adjust if necessary. The correct pH for marijuana is 6.3 - 6.8 in soil and 5.5 - 6.1 in a hydroponic system. Second, make sure you are giving the correct amount/type of fertilizer/nutrients. For the vegetative stage of growth marijuana needs a fertilizer/nutrient with a high Nitrogen (N) content like 2-1-1 (or 20-10-10).
Yellowing - Upper (New Growth) - Yellowing of the upper (new growth) of the plants could be a sign of a Sulphur (S) deficiency. Sulphur deficiency is pretty rare but usually start off as a yellowing of the entire â€˜younger' leaf including the veins. Other signs of sulfur deficiency are: Elongated roots, woody stems, and Leaf tips curling downward. **Note- Most yellowing of the upper leaves is a bleaching from being too close to the lights.
Solution - Check and adjust the pH level as necessary. Check your fertilizer/nutrient levels and make sure you are giving the correct amount/type for you particular stage of growth. Also a good test to see if your lights are too close is to put your hand between the light and the plant. If your hand gets too hot for comfort, the light is too close and needs to be moved up higher.
Leaf Curling Up - Leaf curling up can be a sign of a Magnesium (Mg) deficiency caused by too low of a pH level. Magnesium deficiency will show as a yellowing (which may turn brown and crispy) and interveinal (in between the veins) yellowing beginning in the older leaves. Interveinal chlorosis (yellowing) will start at the leaf tip and progressing inward between the veins. It could also be a sign of excess heat and humidity in the grow room.
Solution - Check and adjust the pH level as necessary. When the pH is not at the proper level marijuana will lose its ability to absorb some of the essential elements required for healthy growth. If you're growing in soil Magnesium will begin to be locked out at a pH of 6.5 and lower, in hydro it starts at 5.8 and below. If the pH is correct, then add 1 teaspoon of Epsom salts per each gallon to your water. Or, to foliar feed them, add a ½ teaspoon per quart to a spray bottle. **Note- If your tap water is over 200 ppm Magnesium will be locked out due to the calcium in the water. Magnesium can get locked out by too much Calcium (Ca), Chlorine (Cl) or Ammonium Nitrogen (NH4+). If this is your problem we suggest using bottled or RO (reverse osmosis) water.
Leaf Curling Down - When the leaves curl under and burn at the tips and margins it's usually a sign that the nutrient level is too high.
Solution - Check and adjust the pH level as necessary. Flush and decrease the nutrient level.
Droopy Leaves - Leaves that are drooping are most likely caused by over watering/under watering or lack of light.
Solution - First off, for soil, Place you finger into your soil a few inches and see if it's dry or wet. If over watering is your problem, increase the temperature and airflow to evaporate some of the excess water also you can add some h2o2 when watering to help the roots still receive O2. **Warning!- Chronic over watering can lead to soggy roots and stagnant, icky soil. if you slide the plant out of the pot to check the soil and it stinks or is soggy then transplant into fresh dry soil. For a hydroponic system, check to see if your medium is dry or wet before you water (or your pump comes on). If your medium is still pretty wet, then you are over watering and need to water less often. If your medium is very dry before watering, under watering is your problem, just water more frequently. And lastly, If lack of light is the problem, Add more light.
Root Bound - Root bound is where the roots of your plant outgrow the container they are potted in. Plants that are root bound exhibit stunted growth, stretching, smaller and slower bud production, easier to burn with nutrient solution, needs watering too often, and wilting. A root bound plant will always start yellowing with the bottom leaves and work its way up the plant until all the fan leaves are gone.
Solution - To fix this problem you need to transplant your plant into a bigger pot. The 'rule of thumb' with soil is 1 gallon of soil for every foot of growth except for clones which can use a smaller size. So a 2' tall plant is going to need AT LEAST a 2 gallon container. First thing you need to do is gently remove your plant from it's smaller container. While it's out, inspect its roots, if the roots run in a tight circle around the outside of the root ball, you caught it just in time. Very carefully use your fingers to dig into the outside 1/2" of these circular roots, loosen them up and pull them gently (yes, I said gently ) outward. If the roots are extremely tight, you can VERY carefully slice a thin layer (less then a ½") off the outside of the entire root-ball. Once you have tended to the roots It's time to replant it. Set the now un-bound root-ball into its new larger pot.**Note- Do not pack down this new soil, you want the soil to be settled (with no air pockets) but loose enough to allow the roots to easily penetrate it.
Stunted Roots - Stunted roots (slow or no new root growth) is could be caused by a calcium deficiency, aluminum toxicity, copper toxicity, pH acidity, or soil toxicity.
Solution - As always check and adjust the pH level as necessary. If soil toxicity, of any kind, is your problem then you need to flush it real good.
Stem Breakage - Everyone from time to time has had this problem or will. This is when your stem is broken. Stem breaks can come from a number of things: training, dropping something on it, animals, weather. No matter how it happened the most important thing is to not panic.
Solution - Fixing this is not really a problem. Splint it with something and tape it in place. Marijuana has a great ability to come back even after a stem break. Give her a week or so to recover before she will start to grow again. And be more careful next time!
First off, our grow guide has a great section on insects and animals that should be read. ( Deer, Rodents and Insects) Here is a recipe taken from there for an organic insect repellant.
3 hot green peppers (canned or fresh)
2 or 3 cloves garlic
3/4 tsp liquid soap
3 cups water
Puree the peppers and garlic cloves in a blender. Pour into a spray bottle and add the liquid soap and water. Let stand 24 hours. Strain out pulp and spray onto infested plants, making sure to coat both tops and bottoms of leaves.
The best way to keep insects out of your garden is to be Pro-active and always on the look out for trouble. At the first signs of an infestation you must move quickly or quality and yield will be greatly affected. Since we are growing a consumable crop, getting rid of any insects prior to flowering is an absolute must. It's VERY important to enter flowering without any bugs! We cannot stress this strongly enough, it's about removing all bugs from any plants in the vegetative stage so the problem isn't carried into flowering. We all want the yield/potency to be the most it can be and it can only do this without any bugs attacking its systems.
Aphids - Aphids are soft-bodied insects that use their piercing sucking mouthparts to feed on plant sap. They usually occur in colonies on the undersides of tender terminal growth. Heavily-infested leaves can wilt or turn yellow because of excessive sap removal. Aphids produce large amounts of a sugary liquid waste called "honeydew". The honeydew that drops from these insects can spot the windows and finish of cars parked under infested trees. A fungus called sooty mold can grow on honeydew deposits that accumulate on leaves and branches, turning them black. The appearance of sooty mold on plants may be the first time that an aphid infestation is noticed. The drops can attract other insects such as ants, that will feed on the sticky deposits. Infestations generally result from small numbers of winged aphids that fly to the plant and find it to be a suitable host. They deposit several wingless young on the tenderest tissue before moving on to find a new plant. The immature aphids, or nymphs, that are left behind feed on plant sap and increase gradually in size. They mature in 7 to 10 days and then are ready to produce.
This something that I have done up for myself mainly incase I have problems etc.
Its mainly a collection of info from various websites and books that I have read.
I hope it helps someone.
Last edited by Medical Marijuana; 05-14-2008 at 05:11 AM.
Re: CF and PH levels, And troubleshooting plant problems.
Will PH 'downing' every day effect plants or irrigation system etc? I am using ice blocks to cool my nutrients to 22c, which seems to raise my PH levels overnight by almost one unit. Is there any other factors that may be raising my PH levels so rapidly other than the ice blocks? Also, would adjusting the PH in the water blocks before freezing be effective?