Cloudy Water in Planted Tank

I have no idea what is causing this but it has been going on for 2 weeks or so now. I have searched the internet and the two options seem to be algae bloom or bacteria bloom. Every morning the tank is very cloudy. As the day goes on, the water clears up. Then the next morning it is cloudy again.

So what would cause cloudy water in the dark with lower co2, then clear up with light and co2?

I am running 2.9 WPG for 9 hours, pressurized co2 at 30 PPM. (Turned off at night). Fish load it light for a 75 gallon.

Water tests show the following levels

Ammonia 0

Nitrite 0

Nitrate 5 PPM

Phosphate .5 -> 1 PPM (Hard to tell for sure on the color chart)

I am using the EI fertilization method.

Looking at the aquarium from the front it shows some cloudiness but if you view the length of the tank by looking into one end, you can not see through the water. This cloudy water was triggered by a large trimming and water change a few weeks ago. Maybe it is a bacterial bloom but It is interesting how light and Co2 make it go away.

Brown Algae

Well my planted aquarium has been running like a charm for the last month or so. After the weekend water change my water was cloudy for a day or two, and now I have this slimy brown algae. I have had this cloudiness before and suspected a bacteria bloom. When I test the water I have 0 nitrites and 0 ammonia. So it remains a bit of a mystery but does clear up in a few days.

After the cloudiness, I am left with this brown algae that looks slimy and easily floats of off the plants. I have had this type of algae before. If I didn't know any better I would think it is Blue Green Algae. The difference is it does not grow in sheets but strands, its not blue green, and it does not smell. This does not seem to common of an algae for planted tanks so maybe I will post some pictures in hopes of helping anyone else who comes across it.

I try to keep phosphates under 1 and they where between 1 and 2. Some people can fertilize their phosphates between 1-2 PPM but I always seem to get into trouble closer to the 1 PPM mark. Perhaps this is the trigger.

I will wait it out, do an few extra water changes and it should pass. I want to get things cleared up so I can start to sell/trade the plants online. I trim enough plants on a weekly basis to easily plant a 10 gallon aquarium and I hate to throw them out.

I will update tomorrow with a pic of the algae. Hopefully things have started to clear up.

Aquarium and Plants

Here is a picture of the tank.



I currently have the following plants

Potamogeton Gayi

Eusteralis stellata


Bacopa Monnieri


Limnophila sessiflora


Hygrophila polysperma v. sunset



Hemianthus Micranthemoides

Ceratopteris thalictroides

Hygrophila polysperma 'ceylon'



Rotala Indica

Ludwigia Repens


Heteranthera Zosterifolia

Taxiphyllum barbieri

Nesaea pedicellata

Dwarf Sagitaria


I have had very good success with all these plants except the Rotala Indica. It grows really slow in my setup. I suspect it is the hard water.


It is worth mentioning that although there are "Recommended" water parameters for a planted tank, save yourself the hassle and just use your tap water. My water is extremely hard (23 GH, 11 KH) and has a high PH (8). Since I use pressurized Co2 I have brought the PH down to 7. I do not use any type of buffers, softeners etc in the water and have to sometimes trim the plants twice a week.