Hazy, cloudy water issues

The friendliest place on the web for anyone with an interest in aquariums or fish keeping!
If you have answers, please help by responding to the unanswered posts.


Aquarium Advice Activist
Jun 11, 2005
Rogersville, MO, USA
Hello everyone. I am having a hazy, cloudy water issue. My tank:

10g (planted within the last week)
7.2 pH
0 ppm ammonia
0 ppm nitrites
10-20ppm nitrates
13º GH
78º F
Small HOB Whisper filter (I believe) that came with it.
Air Pump
Hagen CO2

My tank is almost a year old and seems to be doing well but within the last 4 days the water has started to get whitish in color and hazy. All my tests seem to show everything is alright. BTW I test daily since bringing my fish up to 10 to make sure there are no spikes. 3 days ago I did a PWC and just this morning I decided to do a PWC. But still pretty cloudy water. I am pushing the bio limit of my tank with 10 fish some shrimp and snails. But with the aeration and weekly PWC my testing has not shown any spikes in ammonia or nitrites. Nitrates have steadily hung around 20 ppm. That is why I decided to put some live plants in the tank. To get some natural help with the nitrates. Just to give you a history:

Last Saturday (4 days ago) I added Laterite substrate (I washed it even so the water turned brownish but cleared within a day) Anacharis and Microsword. I also added a higher wattage fluorescent bulb (5500-6000K and a total of 2.1 WPG) and a Hagen CO2 system for the plants. 2 days ago I finally purchased a test kit for water hardness and discovered my GH was high. Finally yesterday I purchased a water softener pillow and my GH has dropped to 8º.

Am I doing to much? Not enough?

I think you stirred up the substrate enough with the addition of your laterite and the planting that you are having a bacterial bloom in the water column. This is not unusual when the gravel gets disturbed in such a way, and it will clear up on its own, so be patient and it will resolve. It is not in any way harmful to the fish, it just looks crummy.

I would not do anything different, except don't do any water changes until it resolves, unless the nitrate rises or you see ammonia or nitrite. I would imagine your plants will uptake any of these compounds, though, since you have good light and the CO2. If you have a bubble curtain running with your air pump you might consider removing it to conserve CO2 gas, especially with the plants in there, which should be providing plenty of oxygen for the fish.
Thanks TankGirl. Since I did do that PWC this morning I'll keep a close eye on my readings. I'll pull out the bubble curtain in a day or two when I know the Hagen is actually producing good CO2. Thanks again.
I've cut off the bubble curtain and retested. Here are my results:

7.2-7.4 pH
0 ppm ammonia
0 ppm nitrites
10-20ppm nitrates
4-5º KH
7-8º GH

I see that the softener pillow is doing its job! I am also curious how long might a bacterial bloom last?

Also other than checking the CO2 levels by KH and pH is there another test for CO2. I'm curious how much CO2 my Hagen unit is actually putting into the tank.
The most reliable way I know of to check CO2 is to use the pH KH calculation. There are CO2 test kits out there but I don't think they are accurate at all.

A bacterial bloom can last a week or two.

BTW, there is nothing particularly bad about dGH of 13.
Thanks for the reply TankGirl. I've pulled the pillow out and I am going to leave the dGH around 8. My line of thought was that a middle of the road reading would be best. I still need to test the tap water before I put it into the tank. I haven't done that yet to see where I am in all readings.
Wow, when I turned on the hood lights and checked the tank this morning the haze had gotten much worse. It was hard to see the back of the tank. I immediately checked my levels and everything was fine.

7.0 pH (pretty sure on this one)
0 ppm ammonia
0 ppm nitrites
10ppm nitrates
5-6º GH (pulled the softener pillow out yesterday)

The fish seem to be doing just fine so I assume it's my bacterial bloom ramping up. I didn't think it would become much denser though...?

On the CO2 front though if my calculations are right with KH and pH my CO2 levels have been rising nicely. I should be at 18ppm CO2. I know pH is supposed to drop when CO2 is added but is KH supposed to rise as well?
No, KH should not rise, but I'll bet removing the softener pillow had something to do with it.

Watch this tank carefully because from experience green water can often start out as a cloudy tank resembling a bacterial bloom, only to turn pea soup green. The fact that it is worsening sends a little flag up to me... :|
The KH should not change.. the CO2 adds more acid to your system and the KH buffers that acid it doesnt change how much KH is there it just works the KH harder... does that make any sense?
And Im assuming your haze will settle down after a while.. see if it doesnt get better in a few days..
Thanks greenmagi and it does help. It just seems odd that with no buffer addition or other water changes for a couple of days that my KH would raise. I've tested everything (including KH and GH) twice a day for well over a week now. I'm guessing that it isn't a single bad test reading so I am still at a loss for the increase in KH.

Also with my CO2 on the rise should I boost my WPG above the 2.3 that it is at now? What is a good K temp for the fluorescent lamps?
I'm no lighting expert, but I would say don't make any changes until you have determined what caused the bloom and it settles down.
I agree that you ought not to make any changes right now, especially with whatever this bloom might be.

The only reason to increase lighting is if the plants you are trying to grow require it. Otherwise, don't make life harder for yourself with more light. Somewhere from 65,000K to 10,000K is ideal.
Yep, and as a professional typist I will now have to take myself out back and administer 40 lashes with a USB cable. :oops:
8O 8O 8O HOLY CRAP!!!! I got home about 30 minutes ago and when I checked the tank it was white. I mean you could barely see anything moving in there. All I kept saying way "HOLY CRAP". I immediately tested and found:

6.8 or 6.9 pH
0 ppm ammonia
0 ppm nitrites
0 ppm nitrates

CO2 must be at between 26-33 ppm. I immediately disconnected the Hagen CO2 reactor, turned the output flow of the Emporer 280 to max, and put my bubble curtain back in there on full. I'm hoping that I've adding enough surface agitation and oxygen to drop the CO2 levels soon. I can see the fish in there moving but it must be hell.

I'm still confused by the rising KH level. Each reading over the last several days has indicated rising KH. I must have to do with the addition of CO2 because that is all I have added. My other surprise of the afternoon was the almost instantaneous loss (It dropped 10-20 ppm in 10 hours) of nitrates. With that much CO2 the plants must be using an aweful lot of nitrate...

Has anyone else experienced CO2 causing the hazing I'm seeing?
I do not think it is CO2 doing this. The fact that your nitrate is down to zero really makes me think this is going to be green soon. Green water consumes nitrate at an astounding rate and when you test for it with green water it is almost always going to be zero.
So an algae bloom??? Why in the world would I have such an increase of KH and a decrease in pH over 4 days if all I've added area plants and CO2? The pH I understand, because there are enough posts about that fact. I would put my KH readings to n00bish screw-ups if I haven't been taking reading twice daily and even more than once per setting to verify what I've gotten. What else can I test for? Should I do a major water change? I'm guessing now that this isn't a bacterial bloom my tank is experiencing? Wow, I went almost 8 months with a tank that was stable and it's falling apart now. I hope the fish make it.
Top Bottom