Green Water

[llebles]

I am stumpted. A friend has a little 20 gallon goldfish tank she filled with water 3 weeks ago. There are no fish, nor has she put fish or fish food in there. Just a couple fake plants and some pink gravel.

Since she had no nutients, so I figured if she just covered it for 3 days to deprive the algae the ability to photsynthesize, it would go away, After a week of being covered, she still has it. She has tried totally emptying the tank and starting over. She has the same city water I do, and I don't get green water...even when I over-feed.

Anyone have any ideas?

 

[Fat Homer]

i know you said your friend covered the tank for 3 days, but is the tank near a window by any chance? and does it have a filter running? maybe its something in the filter feeding the algae? or maybe its another form of algae (can't rmb the name of it) but its known to cover surfaces like algae...

 

[llebles]

Here is basically what she did. She got a new feeder comet that had ick, and it died. She broke down the tank, cleaned the tank and the filter out with a scubbie pad and bleach, let it dry. Then she put new pink rocks (ew!) and filled it with water.She put a new 10 cent comet, and it looked bad. I tested the water, and gave her the nitrogen cycle speech....and told her to move the ailing fish to another tank. She has 2 other tanks that are well established. The cheap comet is just fine. However, she has this pea soup water in the empty tank. She claims that the tank has been covered for a week, she said she has changed 80% the water twice, the green water keeps comming back.
She has also tried an algae remover which she has used on occation for her other two tanks.
I know that basically green water comes from too much light and too much fish waste/uneaten food. She doesnt seem to have either problem. I seem to recall something about phosphates causing this too. I wonder if the new pink rocks could be leaching in some way? I doubt its the water, we live in a big city and share the same water source. I have 5 tanks, and I have only had pea soup once years ago with a ew tank and I used black colored rocks. Since then, I have always used pool filter sand, pea gravel from the home center or crushed coral.