I set up my SW tank about the 15th of November. All ammonia, nitrites, and nitrates were zero by December 20. I have been changing 25% water each week. Last week, the water turned green overnight. It is so green I can only see about 3 inches into my tank. I changed 80% water, next day I changed 80% water again. No help. Waited 2 days, changed 50% water. I was using tap water and adding salt. With the second 80% water change I started getting salt water from LFS. No better. I installed a protein skimmer 2 days ago. It is removing some bad stuff - about a half a cup a day. The water seems to be a tiny better, but I still can barely se my LR.
28 gal tank
13 lb LR
2 in LS
3 damsels
6 turbo snails
10 margarita snails
1 emerald crab
All animals seem to be OK, not even showing any stress.
What is wrong? What should I be doing?

Green water is usuallly the result of too many nutrients in the water. Your tests seem to indicate this isn't the case with your tank. Filter feeders love green water so something likeTube Worms or clams might take some of it out. You have some very tough SW animals in your tank so you don't need to change water so often, try once a month. This may be part of the problem, the water change adds nutrients. For a protein skimmer to have full effect on a tank takes several weeks and it needs older water to works right It should also pull out some of the greenwater animals.

Any time you have something growing out of control you have to figure out how it is getting what it needs to survive and reproduce, 'cause that will be key in reducing the population. With green water you need to figure out how to reduce nutrients (food) and light.

Are your ammonia, nitrite and nitrate still at zero? With all those water changes it might be, but double check your tests. I'm guessing somewhere in the green darkness there's probably extra food or something supplying nutrients for all that green stuff. I would not decrease the frequency of water changes, unless & until you test your tap (or whatever your source of water) and find your source has high ammonia, nitrite or nitrate. If it does not, then it is not the source of your nutrient problem. If it isn't, then the nutrients are coming from somewhere else, either inside your tank (a dead fish or dead plants or a build up of uneaten food?) or from overfeeding.

If it is your water, then the solution is getting a reverse osmosis unit or some other source of water change water that is lower nutrient than your tank, and is going to help you lower those nutrients, 'cause the organisms that make up green water need something to eat, you starve them, they will stop reproducing and your removal efforts will be more effective.

Light: You can cut down your light hours per day for the tank as well. That will limit the green water's growth and reproduction. Plus if your tank is in direct light, like next to a window? it should probably be moved to another location. Cutting the light will slow things down, but so long as there is some light there will be some growth and reproduction from light so long as there are also nutrients.

for cloudy tanks I kill the lights and stop adding food. In a few days (week or two at most) the water is clear again.


my .02

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fw leiden since 1979, fo salt since 1979, mixed reef 55g 2002-2009. Strong emphasis on the tank taking care of itself. Balanced with plant life, no water changes, tap water, no filters in FW. Only dosing calcium, alk, mag in marine reef tanks. http://www.aquariumforum.com/f15/my-...ods-26410.html
recent tanks (till 2009) 7 years- 10g FW leiden 7 yrs, 55g mixed reef 7, 2 yrs, 20g FW leiden, 10 g fw leiden , 29g mixed reef, current tank 55g leiden

Thank all of you for your help. You have given me several thinks to work on. What I didn't tell you is that the pH is steady at 8.4 Since the trouble started, I looked under the LR for something dead and found nothing. I also added two pieces of LR. I will reduce the water changes. Sounds like I have to try the things you suggested and have patience. About the nutrients, the food I have floats. However, the water circulation is with two pumps in rear chambers and an overflow return. The food exits with the overflow. I vacumned those chambers and I have been turning the pumps off when I feed them for the last 3-4 days. I am sure I have been feeding too much.

I forgot to mention that I also have 1 chocolate chip starfish and 1 sand sifting starfish.

Well, after trying several things, my tank water finally cleared up. No harm to my critters, but the water was green and opaque for about 3 weeks. I did several things the latest of which was to block the outside sunlight. This seemed to do the trick. I don't know for sure though since I did so many things.

FWIW I had a marine tank that I added some macro algaes to. the Problem was that is was summer so the macro had been exposed to 4 days shipping no light and the outside temperatures were like 90-100F. Plus the tank I put then in had unmeasureable nitrates as well.

What happened is the macros entered the sporate or sexual form of reproduction and the tank clouded up in two days.

It took over a week for the to clear up with lights out.

So in extreme cases it can take some time for the water to clear.

But IME the always clears up with a blackout. and stays much clearer after the blackout as well.

For more normal operation it can take some adjustments to keep it clear.


Glad it finally cleared up for you and I have no doubt the blackout cleared it up.


my .02

__________________
fw leiden since 1979, fo salt since 1979, mixed reef 55g 2002-2009. Strong emphasis on the tank taking care of itself. Balanced with plant life, no water changes, tap water, no filters in FW. Only dosing calcium, alk, mag in marine reef tanks. http://www.aquariumforum.com/f15/my-...ods-26410.html
recent tanks (till 2009) 7 years- 10g FW leiden 7 yrs, 55g mixed reef 7, 2 yrs, 20g FW leiden, 10 g fw leiden , 29g mixed reef, current tank 55g leiden

I had this problem once also, a Vortex filter with diatom powder can clean the water up pretty quick. Just a thought.

Would a uv sterilizer have worked?? From what i was told not to put it in for at least a mnth on starting a new tank?

Green water is a funny animal. When you want to make it, it doesn't appear. When you don't want it it's there. I would suggest you stop making water changes for a few days and then only generate new saltwater with distilled water and salt mix. Two things Green Water needs are nutrients and light. Try and cut back on the intensity and hours flight your tank gets. Remember that a Green Water tank is not unhealthy just ugly!

I had this problem. I reduced the hours of light to the tank, although affecting coral growth, it started to have a small effect on the 'green'. I performed a small water change from salt to unsalted, to lower the salt level, and left the tank running for two days with no light. Cleared up a lot over that small space of time