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Originally Posted by rybal |
Having read the entire post start to finish, here's my 2 cents based on the excellent link on glutaraldehyde above
96h acute Grass shrimp LC50 = 41 mg/L
48h acute Daphnia magna LC50 = 0.35 mg/L
48h acute Daphnia magna LC50 = 16.3 mg/L
21d reproduction Daphnia magna LOEC = 4.3 mg/L
NOEC = 2.1 mg/L
96h algal growth inhibition Selenastrum capricornutum ILm = 3.9 mg/L *
96h algal growth inhibition Scenedesmus subspicatus EC50 = 0.9 mg/L
Bacterial inhibition Sewage microbes IC50 = 25-34 mg/L
Based on the pdf link above + observations of cloudy water by other members, Excel causes bacterial inhibition (eg "sewage microbes" above aka nitrifying bacteria).
There may be a compounding effect at play here, any thoughts?
Hypothesis: Excel kills algae at low ppm, inhibits (kills) bacteria at higher ppm (perhaps at levels 2x3 times used as doses by most members)
dead algae + reduced bacteria = altered nitrogen cycle in tank. In this logic, we may also experience an increase in ammonia + nitrites as a result of decomposing bacteria and lack of nitrifying bacteria to process waste.
This, in combination with the effects of Excel's active ingredients, may lead to an increase in available ammonia/nitrite which can:
1) harm fish/invertebrates
2) give plants a nice dose of nitrogen which is easy to uptake (this may explain some explosive growth as documented by others).
Quote from pdf link below:
"Five-day biological oxygen demand and aquatic metabolism studies indicate that glutaraldehyde degrades readily. Accordingly, significant degradation is expected during passage through sewage treatment
works. Reaction with proteins present in sewage effluent will also remove significant amounts from aqueous waste streams. Any glutaraldehyde that may enter receiving waters is likely to be rapidly diluted and undergo further biodegradation." Keep in mind our experiences differ based on water quality. The RO water in one aquarium will require lower dosages than the rarely changed, high TDS water in another - based on "reactions with protiens present in sewage effluent..."
Just my thoughts and something to be mindful of when selecting your dose.
1) how many protiens are in my water (how often changed?)
2) will the plants be able to uptake higher levels of ammonia / nitrite resulting from bacterial inhibition?
Any thoughts?
michael
ps isn't ecology wonderful?
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