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Inorganic vs. Organics

I've been gone some time, but I've been lurking. And since this thread is interesting...

The more I experiment, the more I think the algae equation is based at least partly on whether nutrients are organic or inorganic. For the most part, plants can't uptake organics directly, they need bacteria or something to breakdown organics into inorganics. Algae, and especially cyano, can use (simple) organics directly.

My guess is that tanks with low organics (e.g., fish waste, decaying plants) will have less algae. This is what happens in clean, established tanks. Adding mulm helps because it hastens the process.

Dosing inorganics (e.g., PO4, NO3, K+, etc.) will not give algae a benefit over not dosing inorganics. Why? Because you can't nutrient limit algae. I've read algae can prosper with PO4 in ppb range, and it is not feasible to get it into this range (unless you want to run "reef" style). So, you might as well add inorganics to help out the plants.

In addition, some organics, like urea, break down into NH4 quite rapidly. Tom has already said that NH4 has some positive correlation with algae growth. I guess that would be another topic, though.

For reference, my tank is "old school" no water column fertilizing (see <http://www.aquaticplantcentral.com/forumapc/showthread.php?t=2063> where some of the current topic was also discussed).
Peace,
 

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Edward said:
How to explain algae free aquariums with no water changes, inert substrate and high light? Where is the organics negative impact?
Hi Edward,
There are no organics entering in the setup you just described. This is kind of like buying 1 gallon of drinking water, adding some inert gravel and some inorganic nutrients, and then placing it under high light. Result: No algae.

Overload the tank with fish and no filtration, and then you will start getting organics and then algae (I think). Under light load and properly established filters, the organic fraction will quickly deteriorate into inorganics.

Think about this simple experiment: Add a tablespoon of an organic fertilizer, like steel manure, to say a 5 gallon tank. In another tank, add 1 tablespoon of the theoretical equivalent amount of inorganic NO3, K+, PO4, TE, etc. Which tank would get more algae?

Just to be clear, I am not saying that organics are the only reason for algae.

Peace,
 
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