cloudy biorb

Question
My son has a baby biorb aquarium with two goldfish in it. We also have 2 small live plants and 3 little fake ones! We have had it
trouble free for 5 months. Last week he did a 75% water change and
replaced filter with new 'service kit'. He also agitated the rocks at the bottom
to give a good clearout, the first time we have done this bit. 24 hrs later the
tank is as cloudy as a dense fog. The ammonia and nitrate levels were really
high (off the scale on the srips) despite putting in ammo lok and stress zyme. For the past 3 days we
have done a 50% water change adding stress coat and stress zyme each
time. The tank is no better at all. Amazingly the fish seem ok!! How can we
get our tank back to normal. There seems to be no improvement at all.
Thanks.

Answer
Hi Helen;

Cleaning the filter and disturbing the gravel all at once has disrupted the biological balance in the tank. Beneficial bacteria, also called "nitrifying" bacteria cling to the filter pads, decorations, and particles of gravel in the gravel bed. These "good" bacteria process fish wastes. If the bacteria are disturbed too much they can die, or when filter pads or decorations are cleaned or replaced the bacteria is actually removed from the system so they can't do their job anymore. The cloudiness is a symptom of all this and should go away once it re-stabilizes. Keep making the water changes to keep the fish safe until it does. Nitrifying bacteria is slow growing so it could be another few days to a week or more before it settles down. Just don't disturb the gravel or decorations when you make water changes right now. Let it re-establish it's bacteria colonies in those places.

The problem you will have though is that your little BiOrb is far too small for even one goldfish to grow and thrive in on a long-term basis. I know the box that the tank came in shows happy healthy goldfish, several of them in fact, but it is false advertising and irresponsible promotion of the product in my opinion. Small tanks are often recommended as a "starter tank" for goldfish. They are too small even for that. Again, just my opinion. But, I have more than 30 years experience in keeping fish professionally in a retail store and as a hobby. I just want my clients to have healthy fish without getting ripped off.

Your little tank will easily succumb to a biological crash the larger your fish grow and the more waste they produce. Your Baby BiOrb holds about 15 liters of water and the filter pad surface area is just not adequate for goldfish. It can't grow large enough bacteria colonies to process their wastes. If you were keeping fish that stay small such as danios, tetras, guppies, etc., they would be okay. Goldfish just don't fit that mold however. Goldfish grow to be at least 15 to 20 cm long and are huge waste producers. Just one goldfish requires 40 liters of tank water at the very minimum. So, it would be best to get a larger tank of 80 liters or larger with a good power filter that hangs on the back and your fish will love you for it! They will have lots of room to exercise and play around in too. It's so much more healthy all the way around.

Good luck and I hope everything turns out okay...

At Your Service;
Chris Robbins