# Why do I get an algal bloom after a water change?



## endgin28 (Feb 9, 2010)

What kind of algae? Also how much filtration are you running? 

Distrubing the mulm and not filtering the released waste out may be the cause. It builds up, you give it a flush, the bottom is stirred up, and nitrogenous materials suddenly are floating around. Better filtration would process the excess stuff. At least that a testable theory- try some dip strips after a WC, and see if it makes sense.


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## msjinkzd (May 12, 2007)

You could also have someting in your source water (like phosphates) that are leading to the bloom.


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## appleciders (Dec 1, 2011)

The algae is dissolved in the water, turning the water green. I have a little algae on plants and rocks, and a little on the tank walls, but it's really not too bad and it's fairly constant. I'm planning on getting a few shrimp or some snails to help with that. I don't remember the model numbers on the filter, but it's an Aqueon HOB and was rated for a 20 gallon tank, so I'm reasonably sure that I've got enough filtration. I haven't tested my water recently, but I usually come up with nitrates near zero, which I've been attributing to the plants sucking it up as quickly as the fish produce it.

I have been using a gravel vacuum to help clear some of the excess matter out of the gravel when I do the water change. I'll try it without disturbing the gravel and see how that goes.


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