# Why more algae in filter pipes than outside?



## Chris Jackson (4 Apr 2015)

Hi,

I'm just curious as to whether anyone really knows why it is that algae builds up far more rapidly on the inside of in and outflow pipes than the outside?

Cheers
Chris


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## EnderUK (4 Apr 2015)

Probably more sediment, waste, algae and bacteria that just gets worst over time as more waste and sediment sticks to the built up slime.


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## Rahms (4 Apr 2015)

There was a thread recently about the cause of algae, and no-one produced an answer.  So as long as we can't explain algae, we'll struggle to explain this! My inflow is the only one that gives me problems, so my complete guess is the gunk getting drawn in lingers a bit, so it's dirtier than the rest of my tank.


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## Chris Jackson (4 Apr 2015)

EnderUK said:


> Probably more sediment, waste, algae and bacteria that just gets worst over time as more waste and sediment sticks to the built up slime.



Ummm now that sounds plausible...


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## Yo-han (4 Apr 2015)

Fish don't pick on it


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## pepedopolous (4 Apr 2015)

Something to do with the glass focusing the heat/light? Solution = steel!

P


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## Dantrasy (5 Apr 2015)

the flow is consistently higher in the hoses.


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## Chris Jackson (5 Apr 2015)

Dantrasy said:


> the flow is consistently higher in the hoses.



Indeed that is the obvious big difference but why does this high flow rate then induce higher growth? 

Is it as simple as more flow provides more food and produces more growth in the same way as it apparently does for our plants? Or is it more about the faster build up of slime and bacteria that provides a better home or is that one and the same thing?


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## sciencefiction (5 Apr 2015)

Constant supply of micro food/organics.


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## H.. (5 Apr 2015)

I Think Yo-han´s stated the obvious. +1

I never seen an ottosinclus inside the pipes...

H.


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## candymancan (6 Apr 2015)

The reason is because there is more flow, more flow = more nutrients to the plant or algae..  This is the reason why more flow can be good for plants that do not get nutrients from their roots but instead their leaves..  if you have stagnant water you don't get nutrient flow..  But if your water is too aggressive it can feed your plants as well as algae..  I haven't had algae issues in my tanks that have very little flow.. but I do have algae issues in tanks with higher flow I noticed


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## Chris Jackson (7 Apr 2015)

Well yes I thought the obvious flow relationship was interesting which was why I brought up the topic. Clearly that is the big difference from inside pipe to outside but I wouldn't have thought there would be any nutrient limitation between the two as far as algae are concerned though one can summise that there will be far more crud cruising down the pipes. I'm pretty confident that in my case the filter inflow pipe gets gungy rather quicker than the cleaner watered outflow pipe.

I dont think the critter nibbling factor accounts for much, i've never seen a shrimp or otto grazing on my spray bar....


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