Originally Posted by somewhatshocked
To each their own. But...
I wouldn't even use 1ml of metricide per 50gal with shrimp. I've had it kill pretty much every kind of invertebrate kept in the planted tank hobby. Amano included. But Neos and Crystals are especially sensitive to it.
P.S. Yes, this an alarmist take. Meant to highlight a common worst case scenario that shrimpkeepers tend to experience on a fairly regular basis.
I am not convinced that the dosage, 1 ml per 50 gal, which is less than 0.1 ppm Glut, is sufficient to harm shrimp.
According to Seachem, there is no harm to fish and shrimp following its directions: “On initial use or after a major (> 40%) water change, use 1 capful (5 mL) for every 40 L (10 US gallons). Thereafter use 1 capful for every 200 L (50 US gallons) daily or every other day.” 5 ml per 10 gal is equivalent to 2 ppm Glut.
I have compiled toxicity tests of Glut from multiple sources as follows. Accordingly, grass shrimp will be harmed at 41 ppm, sunfish 10 ppm, algae 1 to 1.8 ppm, and daphnia 0.35 ppm. Therefore, 2 ppm as recommended by Seachem is minimal to suppress algae, and double to triple that amount won’t harm fish and shrimp.
Toxicity of glutaraldehyde
96h acute Bluegill sunfish LC50 = 11.2 mg/L
Bluegill sunfish NOEC = 10 mg/L
48h acute Oyster larvae LC50 = 2.1 mg/L
96h acute Green crabs LC50 = 465 mg/L
96h acute Grass shrimp LC50 = 41 mg/L
48h acute Daphnia magna LC50 = 0.35 mg/L
Daphnia magna NOEC = 0.32 mg/L
96h algal growth inhibition Selenastrum capricornutum ILm = 3.9 mg/L
Algal inhibition Selenastrum subcapitata IC50=1 to 1.8 mg/L
96h algal growth inhibition Scenedesmus subspicatus EC50 = 0.9 mg/L
Bacterial inhibition Sewage microbes IC50 = 25-34 mg/L
96h O. mykiss (Trout hatch rate) IC50 = 1.82 mg/L
96h C. dubia (Daphnia reproduction) IC50 = 4.7 mg/L
*EC=Effective concentration; IC=Inhibition concentration; LC=Lethal concentration;
NOEC=No observed effect concentration
I don’t do daily dosage, but dose 5 ml per 10 gal or 2 ppm after weekly 75% water change to suppress algae. The half life of Glut is 10 hours, so by the end of the day there is hardly any residual left. My fish has been subject to as much as 8 ppm short term bath as I dosed the full 5 ml amount before filling up the tank.