Get your answers to frequently asked questions
Q. What is pH?
A. pH is the measurement of acidity (below 7.0pH) or alkalinity (above 7.0pH) of a solution.
Q. Why do I need to measure pH?
A. It is important to maintain a hydroponic nutrient solution at a pH where elements in the nutrient solution are available to the plants. Each element has a pH range in which its availability is maximised. The range in which most elements are available is between 6.0pH and 6.5pH, but some plants will survive in a range between 5.0pH and 7.5pH. Strong acid (low pH) or alkali (high pH) conditions will upset the balance of the nutrient solution and can cause the loss of nutrient uptake by the plants roots. This can cause "lock up" whereby certain elements become unavailable to the plant.
Q. What do I use to measure pH?
A. Meters that measure pH are available from Bluelab retailers. Please click on the following product names for more information. Test strips are available but are not as accurate as an electronic meter. Over time, investing in an electronic instrument is more cost affective and will give you more accurate results.
Bluelab Combo Meter
Bluelab pH Meter
Q. What is conductivity?
A. Conductivity is an electrical measurement of the total soluble salts contained within an aqueous solution. Pure water does not conduct electricity.
Q. Why do I need to measure conductivity?
A. You must know the strength of your nutrient solution. If it is too weak, your plants will miss out on the vital elements they need to grow. Too strong and you run the risk of root burn, especially as evaporation occurs within your growing environment. The nutrient solution needs to be measured regularly so you know when to add more concentrated solution or when to add fresh water. Without an instrument to measure it, you are only guessing and run the risk of a failed crop.
Q. What do I use to measure conductivity?
A. Meters that measure conductivity are available from Bluelab Retailers. Please click on the following product names for more information.
Bluelab Truncheon Meter
Bluelab Commercial Truncheon Meter
Bluelab Combo Meter
Q. What is EC, what is CF, what is ppm, what is TDS, what is mS/cm2 and uS/cm2?
A. They are all different types of readings used especially in hydroponics so we know the strength of the nutrient solution the plants are growing in.
EC stands for Electrical Conductivity. Nutrient ions have an electrical charge. EC is a measurement of all those ions that have an electrical charge. The more electrically charged ions in a solution the higher the EC reading.
CF stands for Conductivity Factor. This is exactly the same as Electrical Conductivity (EC), but does not have a decimal point in the reading.
ppm is parts per million. This is not a measure of electrical conductivity in a nutrient solution, therefore cannot be accurately measured by an EC meter. They are present on the Bluelab Truncheon as a conversion guide only and the scales of ppm they represent are noted. To convert from EC to ppm, simply multiply EC by the ppm scale required, e.g. 2.5EC x 500scale ppm = 1250ppm. The two scales Bluelab use are; 700ppm and 500ppm scale. There are many ppm scales around, but these two are most common.
TDS is Total Dissolved Solids. This is also the 500ppm scale.
mS/cm2 - millisiemens per cm. 1 mS/cm2 = 10CF
uS/cm2 - microsiemens per cm
One millisiemen = 1000 microsiemens
Check out our Conductivity Converter for easy automatic conversions of conductivity. You may also view or print our Measurement Conversion Chart
Q. What is a Bluelab Meter?
A. A meter is a portable instrument that needs to be manually turned on. The probe or probes are inserted into the solution to be measured. The reading is taken then it will automatically switch itself off.
Q. What is the Bluelab Truncheon® Meter?
A. The Truncheon meter is a hand held meter that measures the conductivity of a solution and is only manufactured by Bluelab Corporation, New Zealand. It consists of 4 values, EC, CF, ppm 500 scale and ppm 700 scale. It has an auto sense, so when it is placed in a solution it automatically switches on and after approximately 10 seconds automatically switches off. It never needs calibrating as it is factory calibrated. Please click on the following product names for more information.
Bluelab Truncheon Meter
Bluelab Commercial Truncheon Meter
Q. What is the Bluelab pH Truncheon® Meter?
A. The pH Truncheon Meter is a hand-held meter that measures the pH of a solution. It has a replaceable probe and replaceable contact rings. It is also the only pH Meter in the World that has the one-touch calibration system™.
Q. What are replaceable Contact Rings?
A. Contact rings are reference junctions. Contact rings extend the life of the pH probe of the pH Truncheon Meter. How? The Contact Ring protects the pH probe from contamination.
Q. What are single and double junction pH probes?
A. The reference cell of a single junction probe has a wick or frit that makes direct contact with the solution being measured. They are easy and fairly cheap to manufacture but contamination occurs faster in a single junction probe and generally last 6 months. The reference cell of a double junction probe has a wick or frit that makes contact with a second chamber filled with the same material as in the reference cell. This second chamber has a wick or frit that makes direct contact with the solution being measured. Because it has a second chamber, contamination is slowed. The Bluelab Contact Ring acts as a barrier to the second chamber and is easily cleaned or replaced at a very low cost. The Contact Ring stops contamination getting into the reference cell inside the probe..hence extending it's life. The Bluelab Contact Ring looks like a 'Life Saver' candy so can be thought of as a 'Probe Saver'. Bluelab Contact Rings are replaced on the Bluelab pH Truncheon every six months but this does depend on what type of solution the pH Truncheon is measuring. The replicable pH probe should last 18 months or more when using the Bluelab Contact Rings.
Q. What is a Bluelab Controller?
A. A controller is an electronic device that is connected to a growing system that automatically controls the required parameters for the system and the plants growing in the system. Chosen parameters are programmed into the devise. Switching devices or dosers are used for control to occur.
Please click on the following product names for more information.
Bluelab Dosetronic
Bluelab Peridoser
Q. Why do we use Controllers?
A. Controllers are used to automate a growing system.
Advantages:
Maintaining optimum levels for the parameters you are needing to achieve
Less stress at all stages of growth
Saves the grower time
Eliminates the guesswork
Consistency of Yield - apply the same control with every crop
Monitors the parameters constantly which are visible to the grower
Disadvantages:
Initial set-up cost
Having in-adequate plant management skills
Purchasing a controller not suitable for the job
Not following the manufacturers instructions
Q. Do any Bluelab products have data logging and PC comms links?
A. No, not at this stage.
Q. What are pH calibration solutions?
A. pH probes require calibration periodically to ensure accurate repeatable measurements. Calibration solutions are used to calibrate the probe. These are liquids which are manufactured specific to the calibration process. Bluelab pH products require a two point pH calibration process to ensure the most reliable results.
pH calibration solutions are available in pH 7.0, pH 4.0 and pH 10.0
If a pH below 7.0 is being measured, use pH 7.0 and pH 4.0 calibration solutions.
If a pH above 7.0 is being measured, use pH 7.0 and pH 10.0 calibration solutions.
Ensure the temperature of the solution and probe are as close as possible.
Please click on the product name for more information:
Bluelab Calibration Solutions
Q. Which Calibration Solution do I use first when calibrating a Bluelab pH instrument?
A. If calibrating with pH7.0 and pH4.0, ALWAYS calibrate to pH7.0 first, then pH4.0. If calibrating with pH7.0 and pH10.0, ALWAYS calibrate to pH7.0 first, then pH10.0.
Q. Why do we need to clean the probes on Bluelab instruments?
A. The instrument is only as accurate as the probes are clean!
This is the most important piece of maintenance required on any Bluelab instrument. The probes are what come into contact with the solution and relay the reading back to the instrument for it to be displayed. The probes are susceptible to being contaminated or being covered in a greasy film that inhibits an exact reading. There are no shortcuts to cleaning the probes. It is already a very simple procedure and it will also ensure your instrument measures it right every time.
Please click on the product name for more information:
Bluelab Cleaning Kits
Click below to see how to clean your probes correctly
pH Probe Cleaning
Nutrient Probe Cleaning
Q. What does IP65 mean?
A. I - Ingress. P - Protection. 6 - Totally protected against dust. 5 - Protected against water sprayed from all directions.
Q. My Truncheon Meter does not work! Why not?
A. Ensure the batteries are fresh, if in doubt replace them. Use a quality brand. Do not use rechargeable types.
Ensure the batteries are placed all the same way around, the positive end facing down. Do not mix brands or types as this could cause the batteries to leak. Ensure the batteries are free to move in the battery tube. Make sure the O ring is in place at the top of the battery tube.
Ensure the probe is clean and you are testing your Truncheon Meter in a fresh conductivity standard.
A pinch of salt in a glass of tap water should give an arbitrary reading proving the Truncheon Meter is working. If testing the Truncheon Meter in fresh water (tap water) you may not get a reading as water does not conduct electricity.
Q. My Truncheon Meter measures lower than expected! Why?
A. Make sure the Truncheon Meter probe tip is clean. The use of a non scented liquid scourer is used as the cleaning medium to clean the probe face. Please follow the cleaning procedure as laid down in your instruction manual. Further instructions can be found on this website. Never touch the probe face after cleaning as this will cause probe contamination and lower the readings.
Allow time for the Truncheon Meter to adjust to the temperature of the standard conductivity solution being measured. If the Truncheon Meter is warmer than the conductivity solution, it will measure lower than expected. Allow up to approximately 10 minutes for temperature equalisation to take place.
Always use a conductivity solution that is fresh and of known quality. The Bluelab CF27.7 conductivity solution is ideal. Always replace the cap on the conductivity solution straight after use. Dispose of any conductivity solution 2 months after first opening.
Q. My Truncheon Meter measures higher than expected! Why?
A. There are several explanations for this:
Normally a contaminated probe face will cause the Truncheon Meter to measure low. The Truncheon Meter should be cleaned to remove any doubt and to avoid contamination of a conductivity solution. If you have any doubt about the conductivity solution, obtain a fresh one.
Allow time for the Truncheon Meter to adjust to the temperature of the standard conductivity solution being measured. When the Truncheon Meter is cooler than the conductivity solution being measured will measure higher than expected. Allow up to approximately 10 minutes for temperature equalisation to take place.
The calibration solution may have risen in conductivity or has been contaminated. Leaving the top off a calibration solution for longer than absolutely necessary will cause some of the liquid to evaporate allowing the conductivity of the solution to increase. A dirty Truncheon Meter probe may also introduce contaminants causing the conductivity value to rise. Always ensure your Truncheon Meter has been washed off with plenty of clean tap water and shaken dry before placing in a conductivity solution.
Q. Will low batteries cause my Truncheon to read inaccurately?
A. No. The Truncheon is designed to give accurate readings until the batteries are fully exhausted. The Truncheon will give accurate readings until the batteries have insufficient power to light the LED's. Expect up to two years battery life with normal use when using quality standard batteries. Remove all batteries if the Truncheon is not in use for 6 months or longer. Remove and replace all batteries when discharged or any corrosion / swelling is evident.
Q. Can I use Alkaline Batteries in my Truncheon Meter?
A. Bluelab recommend using the cheaper standard batteries, as Alkaline batteries will last a very long time in the Truncheon Meter and may leak before they go flat.
Q. My Truncheon Meter gives varying readings! Why?
A. There are several explanations for this:
Please ensure the plastic shroud is fitted to the probe. Also make sure the nutrient solution is stirring, you can use the Truncheon Meter to facilitate this.
Allow for temperature equalisation to take place. This can take up to 10 minutes especially if there is a major temperature difference between the Truncheon and the solution being measured.
Q. Can I recalibrate my Truncheon Meter to my conductivity solution?
A. Presently the answer is no. We calibrate the Truncheon Meter by exacting processes which is locked in during manufacture. It is highly unlikely the Truncheon Meter will ever lose its calibration during its life time. All of our Bluelab conductivity solutions are referenced to high class laboratory standards.
