Chemical imbalance

Question
I have a 46 gallon aquarium that keeps turning a green color.  I have 7 African cichlids in the tank.  I did a partial change (about 5"'s)last week and the water cleared up.  This morning I got up to a green tank with chemical levels as follows.  PH very lowat 7.2  Ammonia .50  Nitrite .50 and Nitrate is between 80 and 160.  (colors too close to tell).  The tank has been established for about 3 years and have never had a problem.  So far no fish have died.  Should I do another partial change? If so, remove how much water or should I just add chemicals.  I added PH and Nitraban this morning but think I might need to be doing something els.  Please help!!  

Answer
Hi Geri
I don't know what your normal schedule is for tank maintenance and such, so can't say what's causing all this to go on.  The green water is free floating algae, and I'm sure the high nitrates are contributing to it.  With no live plants in a tank, only leave tank light on for about 6-8 hours.  With live plants, leave it on about 10-12 hours.  Make sure the tank isn't receiving direct sunlight as well.  

For the water quality, those levels are way too high.  Especially the nitrates.  Start out by doing daily water changes of 25% for the next few days.  You don't want to do a large 50% water change at this point, because it looks like your tank is going through what's called "old tank syndrome".  The fish actually kind of get used to the high nitrates, and when you drop them drastically-it stresses them and can kill them.  So, 25% daily water changes for the next 5 days.  Re-check the water parameters then.  You want to aim for ammonia and nitrites at 0 ppm, nitrates ideally you want under 20 ppm.  If after 5 days they're still high, continue with the daily 25% changes.  Once they level out to "acceptable" levels, make sure you change out at least 25% weekly, and stay on that schedule.  Depending on the size of your Africans, you actually may need to increase that 25% weekly, maybe even up to 50%.  But you definitely should be doing weekly water changes.  Also, be sure you're doing a gravel vacuum when you change out the water.  Again, I'm not sure what exactly you do, so sorry if I'm sounding redundant.....but make sure you use a gravel vacuum/siphon and clean the gravel thoroughly each week to do the water changes.  Any leftover food or waste in the gravel will contribute to the high nitrates and other levels being off.

Just curious as well, are you using an undergravel filter?  Because those tend to cause more problems by trapping uneaten food and waste under the plates-which causes the issues you're seeing now.  If so, I'd give thought to removing it asap and using a hang on the back or canister filter instead.

One last thing, if you're on well water, it commonly will have nitrates present in it from fertilizer run off-especially if you're in a rural/farm area.  You can also check your tap water with the test kit.  But usually it's not that high to cause a problem in a tank-and I think you would've noticed it sooner.  

Hope that helps and let me know if you have more questions.

Christy