Nitrates = New Plants = Cloudy Green Water?

Question
Hi Chris. I appreciate you volunteering your time to help all of us out.  I have a 40 gallon tank that was given to me as a gift back in November.  A few months ago, I had a tank disaster and lost several of my fish.  Since, then, I realized that I had over-populated the tank and could not keep the levels in balance.  I have not added any new fish to the tank.  I currently have two nice sized angel fish, two plecos, two painted tetras, one catfish (that refuses to come out of an artificial cave), one domino?, and one neon.  I have done 30% water changes every other week and can't seem to get the nitrate levels to stay down.  The ammonia is at trace levels and the nitrites are reading extremely low if at all.  I read that tank plants will help with this nitrate problem and bought some bulbs at the local fish store.  Within a week the plants began sprouting.  I took out the bulbs that did not sprout.  I have 3 small plants growing in the tank now, but gradually the water became cloudy and greenish.  The nitrate levels are reduced slightly, but the cloudy/green is driving me nuts.  I can't help but think it has something to do with adding the plants.  It has been about a month now and I have done 30% water changes every week.  Initially, it reduces the cloudiness somewhat, but within a day or two it is back to the point that you can't see the fish swimming.  I am only feeding the fish ever 3 days and not so much that there is any drifting after the feedings.  I have even started leaving the light out most of the time thinking that maybe the light is encouraging this cloudiness.  Do you have any clue what I am doing wrong?  I appreciate you taking your time to help.  Thanks so much!

Carrie

Answer
Hi Carrie;

Green cloudiness from suspended microscopic algae or "planktonic algae" is a very difficult problem to solve. It usually has to work itself out over time. The plants would not be the cause of it. Live plants actually help with green water because it feeds on the nitrates the algae likes. Green water really is a waiting game though. Keep up with the water changes and hopefully it will correct itself soon.

You may want to look at the gravel and see if there is a lot of crud in there. Excess crud will cause elevated levels of any or all of the 3 toxins (ammonia, nitrite, nitrate). In an established tank there should be no ammonia and no nitrites. Only nitrates, and they should not be higher than 40 ppm. It is usually controlled by the partial water changes. If you find lots of crud in the gravel, there may be some extra feeding going on you didn't know about, or past overfeeding is still present as waste in the gravel. Vacuum the gravel twice a week while removing 25% of the water for the next couple of weeks to get it under control. Don't do too much of the gravel at once or the beneficial bacteria might get over-disturbed and cause higher toxin levels and more cloudiness. Vacuum half of it every time. You can do one side one time and the other side the next. Or, I like to do it in a checkerboard pattern so the whole tank looks the same. Either way, half of the gravel is given a rest to allow the beneficial bacteria to be stable. This bacteria is what works to keep the toxin levels down and the water to stay clear.

One thing I have found that helps cloudy water clear faster is to add an airstone hooked to an air pump. Extra oxygen in the system helps the beneficial bacteria get control over the toxins and help solve the cause of the cloudiness.

Also, hide the food container and make sure you are the only one feeding the fish. When you feed the fish they should finish all the food from everywhere in 5 minutes. If there is any food on the bottom, floating around, or on the decorations after 5 minutes it is too much food going in.

I hope you and your fish will be "seeing clearly" again soon!

At Your Service;
Chris Robbins