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So I talked with a Dutch friend about this notion of H2O2/Straw further.
He said it(H2O2) will definitely reduce algae if done properly.
Reason is any change (typically raising) in REDOX potentials will do harm to
the algae while the plants seem to actually like it. This makes of sense
based on observations.
Plants do better after a water change(Redox is changed when this is done)
and algae seems to do worse. I know there are some other factors the help
the plants when this is done, but it does make sense. He mentioned that
changing the Redox value of your tank reduces algae has been known to the
Europeans for some time now.
When you disturb the gravel a great deal, often there is a crash in your
tank. The redox potential goes down and takes sometime to reestablish itself
within the substrate. This may also be the answer to Steve Dixon's old
question regarding Liebig's law on why algae does poorly and plants do well
even thought they has the same access to the nutrients in the water column.
Redox readings and nutrient's availability could very well be the balance we
are looking for in the war on algae, not just nutrient management alone.
Higher Redox's can be achieved through good tank management or chemical
means(ozone and H2O2, pure O2 etc).
Funny thing was I used ozone on a FW tank right before I got hooked into
plants about 12 years ago. No wonder I never had algae! I suppose ozone
could also be used but the H2O2 idea is not bad either. I think the Redox
idea seems like a decent tree to bark up.
Plugging through the archives I found some of David's old comments.
>>David Aiken wrote:
>>> Other comments made are that as the redox potential falls, ammonia
>>> becomes favoured over nitrate between +450 and +300 mV ( a later comment
>>> says at less than +350 mV), and Fe2+ over Fe3+ at between +300 and +200
>>> Does +500 mV sound like a reasonable ball park figure to aim for? I hope
>>> so because I'd hate for you to stop reading this list <g>.
George indicated in his post that his tanks were running at
>+500-560mV _without_ the use of ozone, i.e. these were naturally
>occurring levels in a well run tank. They are that high in part because
>plant photosynthesis drives the water to supersaturation with oxygen
>daily - all those little bubbles coming off the leaves in the last half
>of the day.
Good management can accomplish it also but adding a small amount of H2O2 or
ozone could help a little bit? I think this what Amano is trying to do when
he adds O2 to his tanks? Something is up with this. German's, pond people
and the Japanese all are doing it.
Admittedly substrate heating (if used) and water diffusion through
>the substrate would affect that to a degree, but the water movement is
>slow and the redox potential will still drop significantly from the
>levels found in the water column even if substrate heating is used. The
>presence of laterite in the substrate would also help in maintaining Fe2+
>Given the above, I think that it is possible to maintain sufficient Fe2+
>levels in a well oxygenated tank with a redox potential above +300 mV.
>After all, people do seem to be doing it! While I haven't seen George's
>tanks (Colorado is a little too far away from Australia to just pop
>around the corner and take a peek <g>), I wouldn't want to argue with the
>kind of results the photos on his home page show. In summary, I don't
>think iron availability is a real problem at redox levels favouring Fe3+.
>Now, if someone brought out a reliable cheap redox test, I'd suggest that
>we all go out and test the redox potential of our tanks and report
>(there's an interesting research project for someone). I'm prepared to
>bet that the potential in healthy tanks with good plant growth (including
>yours - you also have some nice pictures on your home page) is above the
>+300mV level, and probably above +400 mV. In fact, I wouldn't be
>surprised if George's readings are within +/- one standard deviation of
>whatever the mean is.
Wet/dry filters also seem to have a good effect on the Redox levels also.
Dupla and ADA both have devices to add an oxidizer to the tank. An IV drip
and H2O2 seems to be the cheapest method to me. Barley straw from Dupla
H2O2. O2 added as ADA does seems to be the safest for the fish and plants