[Nalagobi]

Hi. I know that thorough answers require thorough tank specifications. I am asking about a tank my roomate upkeeps and I am not sure about her entire set up. She has had the tank for several years now and it has been successful. She is now encountering a problem with her water: it keeps turning green. I hope I have posted this in the correct thread
Anyhow, I asked her if she knows what everything is that she has ie equipment and such and she says 'no'. So I will explain to the best of my ability since I am typically a freshwater hobbyist only.

The tank is 55 gallons. There is an overflow filter thing behind the tank that runs to a filter system in the cabinet underneath. This filter system has one side filled with blue bio balls which the overflow seems to flow into which at the same time (?) flows into the other side which has a motor and a protein skimmer. I have no idea what this kind of system is called. There are about 7 live rocks in the tank but they dont look very alive....years ago they used to produce red stuff that our mandarin would eat. Now they just look like regular rocks to me. Most came straight from the ocean years ago. There is sand from the ocean that was put in years back as well. She has a light fixture with 2 or 3 bulbs in it in which one is that 'moon glow' that we use at nightime. It seems that suddenly the water just started to turn green. She has done partial water changes every week and everytime the water just turns back to green. There is no visible algae, just green water. There is currently only 1 clownfish in the entire tank which has survived through many things over the years, what a trooper. He is still lively as ever. But... the water is still green.

Is there anyone who has a suggestion as to why, based on these facts alone??

Thanks

[leebca]

WELCOME TO REEFLAND!

You and your roommate are welcome here anytime.

More than likely the nitrates have steadily increased in concentration over the years as the live rock has died out. You may want to read additional info on LR: What is Live Rock, Anyway?

Nitrates are the food for algae. More than likely the 'green water' is a bloom of micro algae. If you have a microscope at your disposal, you may take a look at some water under the scope. You can also filter some water and examine what is on the filter paper/floss/mesh. If it is micro algae, it should show itself.

If you don't see any green life under the scope nor is anything caught on the filter paper/floss/mesh then the colored water could be from a chemical pollutant dissolved in the water. It would be something getting into the aquarium, or over the years has now begun to leach from the substrate and/or rock. It would take an analytical laboratory to test for what the pollutant exactly is, and then you still may not know where it is coming from.

You can take some steps to investigate possibilities of a pollutant by looking at freshly prepared saltwater -- any color to it? Change the source water (See: WATER - Source and NSW). That is, if your roommate was using RO/DI water, try using distilled water, to make up fresh saltwater. I hope your roommate isn't using tap water.

Check equipment, connections, and all plumbing. As some equipment ages, it may oxidize and release chemicals into the water. Check to see if anything is dripping into the aquarium from the light or from any other source.

You'll have to be a bit of a detective if the green isn't caused by micro algae.

Ask if you have any questions.

[Firefish]

A uv sterilizer will clear up that green water fast if it's algae. For a 55 gallon tank you could use an 18 watt... can be found for $35 (ebay) to $80.
This will clear the water but won't correct what's causing the bloom in the first place. You'll have to do some investigation, like stated above.

[returnofsid]

The Bio Balls are probably contributing a lot to the problem. They quickly become "Nitrate factories." Is she using RO/DI water? Overfeeding? There's so many things that could be causing the problem. Is she leaving a window open that, now that the seasons are changing, is getting more sunlight that's hitting the tank?

[Bianca]

Originally Posted by Firefish

A uv sterilizer will clear up that green water fast if it's algae. For a 55 gallon tank you could use an 18 watt... can be found for $35 (ebay) to $80.
This will clear the water but won't correct what's causing the bloom in the first place. You'll have to do some investigation, like stated above.

Lol oh wish I had known this 2 yrs ago. I had green water to my tapwater has high phosphates I used a vortex filter till I figured out it was the tapwater. That thing was a pain to use but water was crystal like air after it was done.

I would have opted for the uv instead back of tank hang on type but good to know now thanks .