FAQs and trouble-shooting tips

Do you have a question about a Bluelab meter, monitor or controller?

There's a good chance someone has already asked the same question, so you'll probably find the answer here.

Bluelab would like to remind all users of Bluelab pH Products that the specified operating environment for any Bluelab pH Probe or pH Pen is 32-122 °F or 0-50°C. This is particularly important to remember at this time throughout many parts North America  and Europe where minimum temperatures are currently well below zero.

If any Bluelab pH product is exposed to temperatures below freezing we recommend that the probe is allowed to slowly warm to a normal room temperature of 70°F or 20°C before it is used.  If this is not done the glass of the pH probe may be irreversibly damaged.


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Top FAQs

How far apart can my connect stick and connect device be?

The line-of-sight distance between a connect stick and the connect device (ie Guardian Monitor Connect or Connect Range Extender) should be:
  • Indoor up to 66ft or 20 M
  • Outdoor up to 164 ft or 50 M

Bluelab recommend positioning your Connect Range Extender and the Guardian Monitor Connect as high off the ground as possible, 6ft / 1.8M is the optimum height.

My pH readings are inaccurate, why?

Possible Reasons: 
  •     Contaminated pH probe (probe dirty)
  •     Incorrect calibration of pH probe
  •     Broken glass bulb in pH probe
  •     Broken stem or connector in pH probe


Possible Solutions:

  •     Clean pH probe as described in article below
  •     Hydrate the pH probe in KCl storage solution
  •     Ensure calibration solutions are fresh and accurate (replace if in doubt)
  •     Wait longer for readings to stabilize before calibrating
  •     Check the pH probe for damage.  If damaged, replace.

What do I use to measure pH?

Meters that measure pH are available from Bluelab retailers. Bluelab products you can use to measure pH can be found in our pens, meters, monitors and controllers sections.

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.

What is KCl storage solution?

KCl storage solution is generally a mixture of Potassium Chloride (KCl) and water. Some brands may contain small amounts of other ingredients.

Bluelab pH Probe KCl Storage Solution is specifically made to work with the Bluelab pH Pen, Soil pH PenpH Probe and Soil pH Probe.

What ppm scale should I use?

ppm measures parts per million.

ppm is known as dimensionless quantities; that is, they are pure numbers with no associated units of measurement. A mass concentration of 2mg/kg - 2 parts per million - 2ppm - 2 x 10-6.

There are many different scales used for different industries around the world and for many different reasons! Did you even know there are more than two scales? The most widely used scales in Hydroponics are the 500 scale, 650 scale and the 700 scale.

CF and EC are measures of electrically charged nutrient ions in a solution.

Pure water will not conduct electricity. Water usually conducts electricity because it is full of impurities, in our case, electrically charged nutrient ions. The two black dots on the end of Bluelab nutrient probes are called electrodes. When these are placed in a solution, an electrical current passes from one electrode, through the water to the other electrode and counts the number of electrically charged ions present. This represents the units measured - CF or EC.

What's the difference?

The ppm 700 scale is based on measuring the KCl or potassium chloride content of a solution. The ppm 500 is based on measuring the NaCl or sodium chloride content of a solution and is also referred to as TDS - total dissolved solids. Individual nutrient ions have different electrical effects! The true ppm of a solution can only be determined by a chemical analysis. ppm cannot be accurately measured by a CF or EC meter. They are present on Bluelab products as a conversion guide only. The conversion is as follows;

2.4EC x 500 = 1200ppm (500 scale) or 1200ppm / 500 = 2.4EC

2.4EC x 700 = 1680ppm (700 scale) or 1680ppm / 700 = 2.4EC

If you are reading from a book that says you should grow your crop at 1100ppm - how do you know which scale the writer is referring to? Is the scale on your ppm meter right for the job? If the book was written in the USA, it could be the 650 or 500 scale. If the book is written in the UK, it could be the 700 scale. If it was written in Australia, well it could be any of the three!

If you must grow using ppm, you will need to know the following;

  • What ppm scale is the book referring to?
  • What ppm scale is your meter using?
  • Which standard or calibration solution should you use for your meter?
  • What ppm scale is the nutrient formula referring to?

We have a conductivity converter that can help you to determine what the ppm may be on your meter or in your book. If we start off with a general idea of where certain crops should be grown using EC or CF as a guide, then this can help determine what ppm the instrument, book, website etc could be referring to. If you need help to determine what conductivity your crop should be grown at we also have a nominal value chart that may help.

Which calibration solution do I use first when calibrating a Bluelab pH instrument?

  • 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.

Bluelab have a range of calibration solutions you can use to calibrate your pH instruments.

Why do I need to measure conductivity?

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.

Read more about measuring conductivity...

Why do I need to use KCl vs tap water or pure water to hydrate and/or store my pH pen or probe in?

Bluelab pH Probe KCl Storage Solution contains the same mix as the KCl reference found in Bluelab pH probes or pens. When you hydrate or store the pH probe/pen in KCl storage solution, you’re re-vitalising the KCl reference solution inside the pH probe.

If you use tap water to hydrate or store the pH probe/pen, it can change or weaken the reference inside the probe. Simply put, tap water is not as effective as KCl.

De-ionized, RO (Reverse Osmosis), or Distilled water should NEVER be used to store or hydrate the pH probe or pen. Pure water changes the chemistry in the reference, causing the pH probe/pen to die.

Why do we need to clean the probes on Bluelab instruments?

A clean probe is an accurate probe!

Cleaning is the most important piece of maintenance required on any Bluelab instrument. The probe comes into contact with the solution and relay the reading back to the instrument for it to be displayed. The probe surface is 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.

Watch any cleaning and calibration demo in our video library, or download a product manual to see how easy probe cleaning is.

Bluelab probe care kits contain instructions and all the tools you need to clean your probes.