EC AND TESTING METHODS
Why an EC number on a coir spec sheet means nothing on its own, and what we do about it.
The problem in one line
Two coir suppliers can both quote "EC 0.5" and be selling genuinely different material, because an EC number is incomplete unless the test method is stated. Change the amount of water used in the test and the same block gives a different reading.
This is not a trick and it is not unusual. It is simply that no single international standard exists for how you measure coir EC, so markets settled on different conventions. If a buyer compares two spec sheets without checking the method, they are comparing two different measurements.
What EC actually measures
EC stands for electrical conductivity. Dissolved salts in water carry current, so the more salt in the sample, the higher the reading. In coir, the salts are mostly sodium and potassium left over from the husk, plus whatever the material picked up in processing. High salt in a growing medium can burn young roots, which is why growers care.
The measurement unit is millisiemens per centimetre, written mS/cm. Some labs report microsiemens, written µS/cm. One mS/cm equals 1,000 µS/cm, so 0.5 mS/cm and 500 µS/cm are the same number.
Why the water ratio changes the number
To measure EC you mix a known amount of coir with a known amount of water, let it stand, then measure the water. The more water you use, the more you dilute the salts, and the lower the reading.
That single fact explains almost every EC disagreement in the trade.
| Method | Ratio | What it does to the reading | Where it is common |
|---|---|---|---|
| 1:1.5 | 1 part coir to 1.5 parts water | Highest reading of the three, because least dilution | Europe, and our house standard |
| 1:2 | 1 part coir to 2 parts water | Lower than 1:1.5 | Common in several export markets |
| 1:5 | 1 part coir to 5 parts water | Much lower again | Some laboratories |
| 1:10 | 1 part coir to 10 parts water | Lowest of these, most dilute | Some markets and older methods |
A block reading 0.5 mS/cm at 1:1.5 will read lower at 1:2, and lower again at 1:10. Same block, same salts, different number.
Our standard: we test at 1:1.5
We test at 1:1.5 for a practical reason. 1:1.5 uses the least water of the common methods, so it produces the highest reading. If a batch passes at 1:1.5, it will also pass at 1:2, 1:5 and 1:10, because every one of those dilutes the sample further and reads lower.
Testing at the strictest ratio means one test result satisfies every market. A buyer who tests our material at their own ratio will get a number at or below the one on our certificate, never above it.
We state the method on every certificate so there is nothing to interpret.
There is no universal "low EC"
Buyers often ask for "low EC" as though it were one figure. It is not. Markets differ, and the thresholds are conventions rather than rules:
| What some markets call low EC | Note |
|---|---|
| Under 1.0 mS/cm | A common working definition in several markets |
| Under 0.8 mS/cm | Tighter, used by some buyers |
| Under 0.5 mS/cm | The strictest common requirement, typically for seedlings and sensitive crops |
Because we wash in-house, EC is a dial we control, not a fixed property of what we happen to have in stock. Tell us the number your market expects and the ratio you test at, and we produce to it.
What this means when you buy
- Ask for the test method, not just the number. A spec sheet without a stated ratio is not a specification, it is a number.
- Compare like with like. If your current supplier tests at 1:10 and we test at 1:1.5, our figure will look higher for equivalent material. That is the method, not the product.
- Tell us your ratio. If your lab tests at 1:2, we will quote at 1:2 so the numbers line up.
- Ask about buffering separately. EC and buffering are two different things. Buffering addresses how the material holds calcium and magnesium. It does not change the salt reading.
Testing we can supply
Our factory runs its own testing on every batch, and we can supply a certificate of analysis with the EC, pH and moisture figures, each with its method stated. Where a destination requires independent analysis, we arrange it through an accredited laboratory.
Some countries go further and require microbiological testing before entry. Australia is the main example, where Salmonella and E. coli status is an import condition rather than a quality claim. We cover that separately in How to read a coir COA.
Related reading
Ordering
We supply washed coir at the EC your market requires, tested at your ratio where you specify one, in compressed blocks, loose bulk or coir-perlite blends. Tell us the EC target, the test ratio and the destination, and we will come back with specifications and a quotation.