I was reading some companies MSDS sheet for it and it mentioned something like 'toxic to aquatic life in at .1 to 1.0mg/l for the most sensative species'. They never mentioned the species but a guess is that the cloudy water some get with high doses of excel is due to a die off of bacteria.
If I have done the math right (I probably have not
) then a 30 ml dose of 2% solution in 60 gallons is .26mg/l, pretty low on their "toxicity scale". That would lead me to belive that the most sensative organisms would be affected. Higher dosing woudl robably affect shrimp or snails, and lastly fish.
Using the same math, 5ml in 10 gallons is about .3mg/l. As I said though, I may not have converted to mg in a 2% solution correctly. I based my figuring on 100g/mol, or 10^5 mg/mol and assumed that one could figure a 2% mol solution in 1liter H2O. Please tell me if I am wrong.