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Title: Why Is My Water Green?
Description: Fresh water tank has cloudy green water

Bessiebean - January 8, 2009 09:33 AM (GMT)
Hi everyone

Just a little question I was hoping someone might be able to help with.
The water in my tank appears to have gone cloudy and now green and I'm not sure why. There isn't any excessive algae growth - I get a some on the glass and hood where the water spalshes that I clean off each week but as the water is so green I'm wondering if this is an algae issue.

My tank is approx 80lts and contains 2 fancy orandas (who I won't be able to see if the water gets much darker!)
It is filtered with an external filter (Fluval 104). This contains mechanical foam filters, a carbon filter and biofilter in the form of clay tubes with room for a topupBiomax filter or polywool . Its bascially the same set up as this

Until this weekend the water was a little cloudy but not quite so green. I'd left my water change for 4 weeks this time to help the water mature. I did a 20% water change and rinsed the filter componants in the waste tank water. I didn't change the carbon, just re-used the same one but I did change out my extra biomax filter for polywool to see if would help clear up the cloudiness. It didn't and now I also have the green problem.

My fish look good and seem well but the nitrate is starting to sneek up a bit (from 5ppm to 10pmm since the water change on saturday).

Not sure if to leave this alone and see if it sorts itself out or if I need to do something.

Thanks for listening :)

Broxandval - January 8, 2009 09:59 AM (GMT)
Hi Bessiebean
How long do you leave your tank lights on per day ?.
As your tank shouldn't be turning green is it on the glass or in the water it'self ? you could buy some King British algae control to get rid of the cloudyness and the green water, this works by attracting suspended particals in the water which clump together and drop to the bottom of the tank where you can siphon it off, if it was just cloudyness on it's own try using accclear which will give you crystal clear water.
Try replacing the activated carbon this should clear up your nitrate problem


Bessiebean - January 8, 2009 11:59 AM (GMT)
Hi Broxandval

It's funny you should ask about how long I leave the lights on as I do leave them on all day. You know it's winter, it's dindgy outside, I thought it would be nice for me and the fish for it to be nice and bright :) It's only when I was reading your post to someonelse here I thought uh-oh maybe I've been leaving the lights on too long. So I'll be doing it just in the evening from now on.

I think the green is in the water as the tank sides seem ok. However when I take out a sample to test it doesn't look green but still looks cloudy...Thanks for the advice of the to the shop then...:)

Broxandval - January 8, 2009 01:33 PM (GMT)
Hi Bessiebean
If the water doesn't look green when you take it out but does when it's in the tank. I'm wondering if the splash guard or glass has algae on it thus giving the tank that green look. :)
You are leaving the tank on all day so that could be the primary cause of things :)
broxandval Fishiedude

Robyn - January 8, 2009 08:10 PM (GMT)
Algae is growing from the light and the waste (leftover fish food and fish waste). You can lessen the first by reducing the time the lights are on. I keep aquarium lights on for 11.5 hours a day but half of my tanks have plants so they need more light. The goldfish only need light to see, find food, and feel like things are right (day and night).

As for the second problem, that can be fixed by doing more frequent water changes. I do change 30-50% of my freshwater aquariums weekly. Since you went a month without a water change, especially if the tank bacteria is not "mature," it's to be expected that the water would go hazy, either white or green or even both. I would change half the water and put in fresh carbon.

For more on aquarium algae, see

I hope things clear soon!

Bessiebean - January 8, 2009 09:15 PM (GMT)
Hi Robyn

Thanks so much for the advice. there's a page here on everything...From reading here I think I definately have the suspended algae...

I've done a 30% water change and changed the carbon plus I got a product from the fish shop called Green Water which helps to bind the blooms together so the water clears. Already about 1hr after treatment the water is so much clearer that it has ever been. The chap in the shop did say as you did to do much water changes over the next few days and treat twice more so I'll do that too. It seems to make sense I guess as otherwise I'll have dead algae hanging about.

I think from what from you've said and reading the page you pointed me to - it's me that's causing the problem. I think I have the lights on for too long - I only have plastic plants so I guess I don't need to leave them on all day long. There is a window opposite the tank which if it's sunny does let light in. I think I'll have to be more strict about shutting the curtains over that window. Also I'm thinking maybe I'm feeding them too much as well. perhaps I should reduce the amount and reduce to every other day and see how we go.

Thanks again :)

Rosiemeadow - January 8, 2009 10:38 PM (GMT)
Bessiebean, You might want to try using barley straw liquid, it seems to work well in my pond, so now I have put some in my indoor stock tank, because my water looks cloudy as well, but I do about a 25% water change weekly,we'll see if it works as well indoors.

Bessiebean - January 8, 2009 11:16 PM (GMT)
Hi Rosiemeadow

Thanks for the advice. What is barley straw liquid and how does it work? It's a new one on me.

With water changes, I had been doing 20% weekly but thought the cloudiness of the water might be due to it's immaturity which is why I left it a month. I thought maybe I was changing too much too often and not allowing the nitrate cycle to get into full swing as the nitrates were coming up a little at the end of each week. I think I might go back to weekly or fortnightly though once the green water is has resolved... :)

Broxandval - January 8, 2009 11:16 PM (GMT)
Hi Bessiebean
I thought it may have been that but I seem to remember that youv'e had the cloudy water for sometime prior to the green haze.
The green water should do the trick, thought the fishshop owner would sort you out some, in most cases about two applications should do along with the partial waterchanges. :)
The white haze you could perhaps remove with a product called Accu - Clear which works in very much the same way as the Green water by attracting then binding minute particals with it and then are taken up by your filter leaving you crystal clear water. :)
I have never been happy with the activated carbon that you get with the Fluval range you would be better off buying loose activated carbon pellets. :)
broxandval Fishiedude

maryannc - January 9, 2009 06:16 AM (GMT)
Could it be you're feeding the fish too much? I had cloudy water in the past due to that fact. Do you have any Pleco fish in your aquarium that could help clean it up?

Broxandval - January 9, 2009 10:30 AM (GMT)
Hi maryannc
The cloudy water in Bessiebean's case has been around for quite a while and it's not down to over feeding her fancies but we do think it's due to the tanks filtration possibly in the material being used at the moment .
broxandval Fishiedude

Robyn - January 9, 2009 07:39 PM (GMT)
More on barley straw:
I have a little barley straw in my freshwater aquariums in mesh bags. It takes time to work so it won't clear up your immediate problem.

Plecos will eat excess fish food but they create a lot of waste themselves. Also, they sometimes will suck on goldfish, and most grow huge, too big for your tank. Plecos can't eat suspended algae. Clams and daphnia can but they wouldn't survive long in your tank. The goldfish would eat the daphnia, and clams require good water quality but a constant supply of suspended life in it to eat.

Broxandval - January 9, 2009 07:57 PM (GMT)
Hi Bessiebean
Barley straw liquid is a treatment derived from barley straw and it's the extract of, if rumour is correct it was actually discovered here in the UK by our very own Southwest Water (rip off b*****d's). :angry:
It was when barley straw bales where dumped in a natural pond green with algae after a while on their return they found the pond to be cleared of all algae.
You can buy it in two forms little straw bales (normally for ponds) or in it's extracted form of liquid. :)
It being pure and natural some fish keepers swear by it . as of yet we have never had to use it but have seen it's effect on peoples ponds so it does work but it takes a little time to be effective. :(
broxandval Fishiedude

Bessiebean - January 9, 2009 08:47 PM (GMT)
Hi Robyn and Broxandval

Thanks for the info on barley straw. A chum at work who is a keen gardener was also telling me she uses it in her ponds...

Robyn, thanks for the link to the info was really helpful to read that you need to have good oxygen levels to use it so i think I'll get may hands on an O2 test kit before giving it a try.

I see it takes a while to work so as you say i think I'll stick with the Green Water treatment I've got at the moment but maybe try it for the future. i take it it can beused as a preventative measure along with reducing light exposure and excess nutrients?

Thanks agains :)

Robyn - January 11, 2009 02:06 AM (GMT)
Yes, barley straw works best as more of a preventative than treatment because it takes time. The extract is supposed to act quickly but I wouldn't use that in an aquarium because aquariums tend to be pretty small (requiring a small, precise dose). A little barley straw in a mesh bag in the filter hasn't caused any problems in my tanks.

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