suddenly cloudy water in 55 gal tank

Question
Hi Karen,

We have a 55 gallon tropical community tank with 6 neon tetras, 6 zebra danios, 1 dwarf gourami, 2 bala sharks, 3 leopard gourami/leaf fish, 3 clown loaches, 4 clown barbs,  2 rosy tetras (still pretty small), 1 dragon goby, 1 knight goby, 1 pleco (who is getting quite huge and probably needs a new home), 2 oto's, 2 dwarf frogs, 3 mystery snails and a few platy's (we got rid of some so I'm not sure how many we have left). We have a dual cartridge Marineland Emperor BioWheel filter.  We've had the tank since February and I'm embarassed to say that we just now changed the cartridges in the filter, as well as replacing the charcoal medium.  Somehow we misunderstood what the previous owner told us about the filter and thought we weren't supposed to change anything in it.  At the same time we changed the cartridge and charcoal we did about a 50% (perhaps a little bit more) water change/gravel vac.  Suddenly we have cloudy water.  You can see through it okay but with the lights on in the tank it really shows how hazy it is because it's so bright.  I tested the water and everything is within specs and not really changed from previous tests. PH is 7.0, NO2 is .3 CO2 is 13 and NH3 is 0.

I awoke this morning to one of the baby platy's having died during the night - but don't know if that has anything to do with the cloudy water. Everyone else seems healthy and happy.  Should we have changed the filter cartridges and medium, then waited and did a water change a few days later?  What should we do to help clear up the water?  We've been doing 25%-30% water changes every two - three weeks and haven't had any problems until now.  Have had the tank since February.

Any advice is greatly appreciated.  Sorry if I gave you way more information than you needed. :)

Trish

Answer
Hi Trish,
Sorry to hear that. I think what may have happened is the overcleaning of the filters and the water change combination may have either removed too much of the beneficial bacteria or stirred up a lot of nutrients and caused a bacterial bloom. This happens a lot. It can be prevented with regular maintenance. Your aquarium is well-stocked and I feel it would be much better of you did more frequent water changes, it can help prevent these cloudy-water problems plus its better for the fish.

If you did it (25-30%) twice a week rather than every two to three weeks would prevent this problem. Or do 50% once a week.

You don't have to change the filter cartridge at a strict specific time period. It is perfectly OK to just rinse the filter media in a bucket of tank water at every water change just to loosen the debri that may clog the water flow. I tend to only replace the filter media when it becomes so clogged its beyond rinsing or it just plain gets worn out and starts to tear. And if you can, only replace half of the filter media one week and then replace the other half the next week.

Definitely try the more frequent partial water changes and I bet you will see a difference. As far as clearing the water, it should eventually clear on its own but once again, a partial water change everyday will help it out a lot.

Best wishes and I hope this helps!
Karen~