In practice, huge differences in the EC level can be found between suppliers although all say that their cocopeat’s EC is below 1 mS/cm. The reason for this is because the measurement method differs.

Progrow Cocopeat is measured according to the Volume Extraction Method using a 1:1.5 dilution. This means that the laboratory takes 1 part of cocopeat and adds 1.5 parts of de-mineralized water to the cocopeat. The cocopeat and de-mineralized water is thoroughly mixed and left to stand for at least 15 minutes. After the standing period the water is drained from the mixture and the EC is measured. For Progrow Cocopeat, the EC reading will be lower than 0.8 mS/cm.

Unfortunately there are different extractions used. Some suppliers use the 1:3 method while others uses the 1:5 method. In the 1:5 extraction method, 1 part of cocopeat is mixed with 5 parts of de-mineralized water. This will obviously lead to a much lower EC reading of the water measured. Practically this means that if the EC in a 1:1.5 extract is 2.0 mS/cm, the EC in a 1:5 extract will be 0.7 mS/cm for the same cocopeat.

Below is a graph illustrating the findings of a leading independent substrate consulting company testing the same cocopeat samples at different dilution extractions.

1:1.5 Dilution

1:3 Dilution

1:3 Dilution

EC

pH

EC

pH

EC

pH

Unwashed Sample A

1.65

6.58

1.40

6.50

0.83

6.66

Unwashed Sample B

2.58

6.32

1.56

6.46

0.91

6.56

Washed Sample A

0.40

6.89

0.20

6.79

0.14

6.95

Washed Sample B

0.36

6.77

0.20

6.65

0.14

6.88

BufferedSample A

0.06

6.90

0.04

6.92

0.03

6.91

BufferedSample B

0.06

6.93

0.04

7.14

0.04

7.20

It is important that the grower familiarise himself with the EC measurement method used by the cocopeat supplier.