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Algae growth related to oxygen levels

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Hey all,

Does a lack of oxygen in a tank promote more algae growth?

I was told the other day that the algae in my tank could be so prevalent due to lack of oxygen, however it doesn't make sense because Algae photosynthesizes right? So in effect if it needed low oxygen to thrive it would effectively kill itself off by producing it?

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Don't know the science of it mate but low oxygenation definitely produces greater algae growth. Just look at stagnant waterways...............always more algae than water with movement in it.

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Don't know the science of it mate but low oxygenation definitely produces greater algae growth. Just look at stagnant waterways...............always more algae than water with movement in it.

Is that because though in stangnant waterways there is no aggitation on the top of the water so algae in gets a chance to stabilise? I had always thought that as algae has chlorophyll in it ie the green stuff. That just like plants on land it needs sunlight and oxygen to grow. And the more of both the better. That is why algae grows close to the top of the water where it is more oxygen rich. Just my two cents and memories of high school biology twenty years ago.

Cheers Mark

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"In the past many believed that NO3 and especially PO4 can induce algae. It has been proven numerous times that these nutrients (even if overdosed) can not create algae issues. Actually the more we dose the less algae we get.

Plant nutrients in general have nothing to do neither with algae issues nor with fish/shrimp issues (dead/sick fish/shrimps) in planted tanks which are regularly dosed with fertilisers!

The question is; “Why do I get algae even though I dose NO3, PO4, CO2 and other nutrients on regular bases”?

The worst mistake many do in such cases is they start reducing nutrients out of fear that these nutrients might be creating the algae issue. Such nutrient reducing method will induce algae even more!

Let’s name the real reasons behind algae issues in planted aquariums which are dosed with nutrients on regular bases:

  1. Low Oxygen level
  2. Insufficient water circulation
  3. Organic build-up
  4. Un-cycled aquarium

Low Oxygen (O2) level can be caused by overstocking, high water temperature (summer time), dirty filters, overfeeding, weak surface agitation.

Insufficient water circulation can cause poor nutrient transport. Even though we dose enough of CO2, NO3, PO4 + traces the water flow has to be strong enough to deliver all those nutrients to the plants. Improve over all circulation (stronger pumps, more pumps).

Circulation will evenly distribute nutrients making them available for plants and bacteria. Aim for a circulation between 5-8 x of the tank volume per hour depending on plants grown and fish kept. Some prefer stronger currents while others weaker ones. Some aquatic gardeners use circulation of up to 10 x the tank volume per hour but they do reduce the water flow by using very long submerged spray bars which should be placed just below the surface.

Surface Agitation will insure sufficient gas exchange and will prevent the surface film from forming. Even though plants will provide lots of O2 through photosynthesis especially in CO2 injected systems it can’t hurt to add extra O2 via the surface agitation.

One should bear in mind that Oxygen is one of the most important electron acceptors involved in animal and bacterial metabolism.

At higher temperatures O2 levels decrease especially during the summer. When the temperature gets higher it is beneficial to create a strong surface agitation or add another power head for this purpose only. I have found that it is not the temperature that affects the fish/shrimp/plants during summer months but rather the low O2 levels. At higher temperatures the bacterial metabolism accelerates and uses up lots of O2 for nutrient recycling.

"

Edited by bidkev

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The above is interesting, just an add on to it.

Algae produces oxygen by day and co2 by nite.

So you can have it in oxygen levels so high they are super saturated by day..... and then come nite they can strip the water of almost all oxygen by morning.

And this is the same species!

Infact when I culture greenwater I do it in oxygenated water. If algae blooms die off, the bacteria bloom that developes to break down the dead algae will also rapidly consume the oxygen. Extreme cases in nature are called 'dead zones'.

In the past many believed that NO3 and especially PO4 can induce algae. It has been proven numerous times that these nutrients (even if overdosed) can not create algae issues.

The above quote is strange, because if you get a bucket of water in full sun, add no3 and po4, then YOU ARE GOING TO GET AN ALGAE BLOOM. And it will happen no matter the o2 levels lol.

I get what is being said, but its being said in such an extreme way that its not accurate for even half the situations aquarists will encounter. Even if it is true for those of us with nice planted tanks.

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The above quote is strange, because if you get a bucket of water in full sun, add no3 and po4, then YOU ARE GOING TO GET AN ALGAE BLOOM. And it will happen no matter the o2 levels lol.

I get what is being said, but its being said in such an extreme way that its not accurate for even half the situations aquarists will encounter. Even if it is true for those of us with nice planted tanks.

I think that what it's saying is that you will get algae anyway, just as your hypothetical bucket would, even without adding no3 and po4

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No plants in tank, water is just green with algae. Its got 2 x 5000lph powerheads in tank, plus sump return near the surface, but theres not much agitation there. Is the flow going into the sump likely to provide enough aeration? The 2 over flow pipes fall straight onto dry japanese filter matt, so theres hardly any splashing.... Ive added a UV light now so that should knock the problem out though right?

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