Green water!! :/ - Tropical Fish Keeping - Aquarium fish care and resources
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post #1 of 10 Old 11-18-2012, 04:49 PM Thread Starter
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Green water!! :/

I am doing a water change with gravel vac every week (about 50l) from my 200l tank.
There are not a lot of fish in there at the moment and Thursday the water went green overnight (water change day is Friday) I did a 50% water change and through gravel vac, left the light off and it is greener now that it was before!!

The problem is probably over-feeding, I realize that. But our fish will eat all their floating food then go and eat the sinking food too! So I put a little more in to make sure everyone gets some!

If there a way for me to cut down on the green? The glass was practically clean so I'm not sure if "green away" or similar products will help?
I did a smaller water change today and the light has been off but its still really green!

Thanks guys,
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post #2 of 10 Old 11-18-2012, 07:25 PM
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when was the last time you changed you filter and how many fish are in your tank? also are you using anything for ammonia?

Last edited by daltonhachey; 11-18-2012 at 07:41 PM.
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post #3 of 10 Old 11-18-2012, 07:55 PM Thread Starter
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The tank has only been running since the beginning of September so the filter hasnt been changed yet. There are 9 neons, 2 dwarf gourami, 5 endler guppies, 3 ottos and one cory catfish in there. Not using anything for ammonia at the moment, it always comes out fine.
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post #4 of 10 Old 11-18-2012, 07:57 PM Thread Starter
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sorry, and one red tailed black shark . . . .
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post #5 of 10 Old 11-18-2012, 08:00 PM
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what kind of filter are you using? and how much sun light is you tank getting with out the light and do you have a light specified for growing plants?

Last edited by daltonhachey; 11-18-2012 at 08:03 PM.
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post #6 of 10 Old 11-18-2012, 08:16 PM Thread Starter
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I have no idea what type of filter it is, it came with the tank (pumps water and air, has a sponge in it) - so did the bulbs, I'm not sure about them either! I am planning on getting a new filter though, everytime I try and adjust this one the top pops off and spouts water all over the walls! The tank isnt in direct sunlight and although there is a big window in the room, it doesn't get particularly bright in there. lights are probably on for 5 hours a day.
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post #7 of 10 Old 11-18-2012, 08:20 PM
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there lots of things the pet stores sell to deal with what seems to be an excess of alge in you tank but you best bet is either getting a new filter, or getting a UV light that deals with algae.
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post #8 of 10 Old 11-19-2012, 12:39 PM
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Bedfore spending money on UV, let's ID the cause and fix that.

Green water is multicellular algae in proliferation to the point that the water clouds green in colour. [What follows is taken from a site on algae, written by Dusko Bojic, to give credit.] The situation that causes GW (Green Water) is usually a combination of high nitrates, phosphates, and mixed in some ammonia/ammonium. Substrate disturbance is usually the culprit. What happens is the algae (GW form) will flourish off of the ammonia/ammonium and phosphate, remembering that algae can consume phosphate easier than plants because of their thin cell walls, the algae uses up the ammonia/ammonium and phosphate, but it doesn't go away...because algae can quickly switch which nutrient it moves to nitrates. So you can see why water changes will not rid a tank of GW. Nutrients can be reduced very low in GW and fairly quickly by the GW algaes, but they can scavenge other nutrients...iron and trace elements. So, it's very common for the GW to solve the situation that causes it to begin with, but that won't eliminate the GW, for the reasons I've allude to. [end of citation.]

Reduce feeding, do good substrate cleaning (open areas) during weekly water changes of 50% of the tank volume. Tank light and ambient room light is also critical. If there are live plants, the light must be sufficient for the plants (intensity) and no more, and then on for no longer than all nutrients are available (duration). A complete blackout (no light, and wrap the outside of the tank in dark paper/towels, etc, to keep it totally dark for 4 days) should deal with this, provided the cause is cleaned up first. Otherwise the green water may return once light is restored.

Do not use any chemical sold for this problem; all of them will cause trouble for fish, and might kill live plants.


Byron Hosking, BMus, MA
Vancouver, BC, Canada

The aquarist is one who must learn the ways of the biologist, the chemist, and the veterinarian. [unknown source]

Something we all need to remember: The fish you've acquired was quite happy not being owned by you, minding its own business. If you’re going to take it under your wing then you’re responsible for it. Every aspect of its life is under your control, from water quality and temperature to swimming space. [Nathan Hill in PFK]
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post #9 of 10 Old 11-20-2012, 04:59 PM
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Add some anti-algae chemicals or get a new filter
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post #10 of 10 Old 11-20-2012, 08:35 PM
kill the lights and stop feeding untill it clears

maintain Fw and marine system with a strong emphasis on balanced, stabilized system that as much as possible are self substaning.

have maintained FW systems for up to 9 years with descendants from original fish and marine aquariums for up to 8 years.

With no water changes, untreated tap water, inexpensive lighting by first starting the tank with live plants (FW) or macro algae( marine)

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