This is part of a series on Aquaponic Water Testing.
Copper is necessary in an aquaponics system in small amount for proper plant growth.
Copper deficiency symptoms include leaves curling and bending downward, a light chlorosis and loss of turgor in young leaves, sunken necrotic spots on leaves, and small leaves.
Hoagland suggests a level of 0.02ppm, which should be safe for aquatic organisms given that the PNEC_Aquatic is 0.03ppm. Most fish can handle larger amount of copper, but invertebrates such as shrimp, crayfish, and snails are very sensitive. Plant roots may start to experience damage at levels >0.1ppm. At 0.3ppm copper begins to inhibit the bacteria responsible for ammonia and nitrite oxidation.
Testing for copper
Most visual colorimetric tests do not have enough sensitivity, however the Taylor K-1730 is on the borderline, and will allow basic copper determination. The most accurate copper tests use the Porphyrin method (Such as Hach 8143), which does not form a strong visual indicator.
- Taylor Technologies K-1730 (0, 0.05, 0.15, 0.3, 0.5, 0.7, 1.0)
- Hanna HI3856 (0.00, 0.05, 0.10, 0.15, 0.20, 0.25 ppm)
NOT AVAILABLE. Manufacturer contacted but even they don’t know why they stopped making it.
- Hanna HI96747 (0.000 – 1.500; Resolution 0.001)
$188 meter @Amazon + $98 @ESeasonGear / 100 = $0.98ea
- LaMotte Smart3 + 3640-SC (0.00-3.50; MDL 0.04)
$27.75 / 100 = $0.28ea
- Hach DR900 + 8506 (0.04 – 5.00)
$38.75@Hach / 100 = $0.39ea
- Hach DR900 + 8143 (0.000 – 0.210)
$190@Hach / 100 = $1.90
The _most_ accurate method available.
- YSI Coppercol (0-5.0; MDL 0.03)
$48.72 / 50 = $0.97ea OR $126.15 / 250 = $0.50ea
What if my copper is too high?
If your copper level is above where you want it and you have sensitive organisms such as shrimp or crawdads, you have two options: Water changes, or CupriSorb. CupriSorb is expensive, but may be regenerated once it’s full of copper.
If your copper level is too high, it’s important to investigate why. If your source water is high in copper you could use a R/O machine or treat makeup water with a bag of CupriSorb.
What if my copper is too low?
Copper Sulfate or Copper Nitrate are the most commonly used forms of copper. Be very careful as you’ll be measuring tenths of grams if you decide to supplement.
Know of a different way to test for Copper in Aquaponics? Let me know in the comment section and I’ll update this post.