My freshwater tank water is YELLOW......?

Question

I have a 55 gallon tank that we just bought and set up on April 30 of this year. The tank has just finished it's cycle (about 1 week ago) and right before it was finished, I noticed that the water had a yellowish cast to it.

Here's what I have in my tank: 2 blue gouramis, 2 dwarf flame gouramis, 3 conga tetras, 1 rainbow shark, 1 pleco and 2 cory cats. I have a Penguin Bio-Wheel 350 filter and a heater, of course. The bottom is white and red rock with 3 castles---1 lg. and 2 sm.---and 2 artificial plants.

When I turn the light on in the aquarium, the water looks fine. But, if the light is off, it just looks yellow/green. The water is NOT murky/cloudy AT ALL. My fish seem to be doing fine. The tank does not sit near a window or any where near where light can hit the tank at all. I don't see any moss growing on anything in there, either....

Any ideas on what's causing this and how I can make my water look clean again?

Thanks in advance,
Karen

My tank does NOT have driftwood or moss of any kind.

I removed the carbon from my filters due to HITH disease a few weeks. The disease seems to be gone. Should I replace the filters with newer ones with carbon in them?

I've been told that the 'rule of thumb' is one inch of fish per gallon. My fish are a total of about 12 inches all together.

Copperhead, yes, my plants are made for the aquarium. Bought them at the aquatic shop. :) Nothing is nearby to reflect yellow into my tank. The wall behind is white and nothing around it is yellow. Didn't use any medication for the HITH disease. Just turned up the heater for a week, removed the carbon and let it ride. :) I do have a vacuum for the aquarium, but haven't used it in 2 weeks. How often should I use it? I don't want to 'disturb' and bacteria, if that makes sense.....I do like to watch my fish eat. lol. So, it could very well be that I'm overfeeding them. :)

Answer 1

The rule of thumb shold be the size your fish are as adults, not the size they are now, but that rule doesn't apply to fish over 1-2 inches long anyway. Could you imaging trying to keep a 10 inch long goldifh or Oscar in a 10 gallon tank? No way is that going to work! But ten 1 inch neons would be fine.

Anyway back to your problem. Do you use a gravel vacuum when you clean the tank? If there's a buildup of wastes it can give the tank water an "off" color. So could overfeeding (only give what the fish will eat in 2-3 minutes twice a day).

Is anything in the tank or in the room nearby green or yellow that might be reflecting? (wall, curtains)

Are your plants ones made for aquarium use? If not, some of the dye might be leaching. You could try removing them and running some hot water on them in a container and see if the color "bleeds".

Did you use any medication for the HITH that had a similar coloring? New carbon might help this if the previous carbon wasn't able to adsorb all the medication.

Answer 2

possible overstocking 11 fish is alot. do you have any snails that may help consume any of the algae? could also be from driftwood in the tank. You may want to try an external canister filter such as a fluval or ehiem on top of the biowheel. these filters are a little more expensive but in the long run you change the filter much less and will keep you tank much cleaner.

Answer 3

Do you have driftwood in the tank? Driftwood releases tannins which are harmless for the fish (some say beneficial) but turns the water yellow. Peat will also do this. Activated carbon in your filter will remove the tannins, you can also do partial water changes to get rid of the tannins.

Answer 4

The reason of the yellow water in your tank is due to urine. I would suggest to put some green food coloring in the tank so it turns blue- the color of water.