water levels?

Question
We "inherited" a 40 gallon tank with 5 large fish, an albino tiger oscar, 2 red-tailed tin foil barbs, a kissing guorami, and a placostamous. We do 25%-40% water changes every weekend due to the high levels of the nitrates and the ph. Immediately after the change, the nitrates are still super high and by the end of the week, the ph is high again as well. We use filtered water from the sparklets machine. What do you suggest we do?

Answer
Hi Michelle

One of the problems is the water you are using. The filtered water from the machine is good for humans, it is not good for fish. It does not have the vitamin and mineral content that they need. Use your tap water with a good water conditioner such as AquaSafe or StressCoat.

Another problem is Oscars are very messy fish and actually need water changes twice a week. I do 30% water changes every Wednesday and Saturday in my Oscar tank.

If nitrates are still high after a water change, then the tank is not cycled yet, or something, probably when you moved it, caused it to start cycling again. Food and waste in the gravel will also cause high nitrates. Do 10% water changes every couple of days and make sure you siphon the gravel thoroughly. Do these 10% water changes until the nitrates read at or near 0. Then do 25% - 30% water changes twice a week. Also change the carbon in your filter once a month.

If the pH is higher at the end of the week than it was when you did the water change, then something in the tank is causing it to rise. Make sure you have no seashells, coral, limestone rocks or holey rocks in the tank. These will all raise the pH. If you have questions about a rock, take it out of the tank and let it dry. Pour white vinegar over it. If it fizzes, that rock will raise the pH.

Another pH culprit is decomposing food and fish waste in the gravel. This will also cause high nitrates which is why it is very important to siphon the gravel with each water change.

Hope this helps you, good luck!

Richard