Bluelab CF Pen

Bluelab CF Pen

In stock

SKU g706

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Description / Bluelab CF Pen

Don’t overfeed or underfeed plants! Monitor your nutrient strength & temperature with a Bluelab CF pen.

It doesn’t cost much, but it’s just what you need.

You can hold readings and choose your units. To make life easy, calibration is optional.

Since temperate affects CF, your CF pen has automatic temperature compensation. That way, you get an accurate reading every time.

It also takes your nutrient temperature, so you can keep it inside the ideal range (18 - 21oC).

Use it every time you change or top up your feed. 

  • Measures CF/EC and nutrient temperature
  • Automatic temperature compensation
  • Choose your units: °C, °F, EC, CF, ppm 500 and ppm 700
  • Backlit LCD display
  • Optional calibration
  • Successful calibration indicator
  • Hold reading function
  • Low battery warning
  • Fully waterproof
  • Auto off function (after 4 minutes)
  • Smart loop handle
  • 1 year warranty included


We recommend teaming this CF pen with a Bluelab pH Pen to cover all bases.

Nutrient strength is measured in EC (electrical conductivity) or CF (conductivity factor).

Both units tell you how many dissolved salts are in your solution. The difference is, 1 EC is equivalent to 10 CF. In the same way 1cm = 10mm.

The EC/CF to aim for depends on how hard your water is and what stage of growth you’re at. As a rough guideline, aim for:

  • Young plants = 6 – 12 CF (0.6 - 1.2 EC)
  • Establishing plants = 10 – 16 CF (1.0 - 1.6 EC)
  • Mature plants = 15 – 20 CF (1.5 - 2.0 EC)

If your feed isn’t strong enough, you could underfeed plants. If it’s too high, plants can dehydrate (not enough water).


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