rust

Question
Hi,

I just set up a new 55 gal freshwater tank and have two filter.  All of my fish started dying and I checked my filters to rinse them and the smaller of the two had rust on the filter.  What could cause this? I've never had lava rocks in any of my tanks before could this have something to do with the rust? Thank you!

Answer
Good afternoon, Deanna, thank you for your question.

Without a better geological understanding of lava rock, I cannot really say whether that is what caused the rust on your filter, but it seems unlikely to me. Lava rock purchased from a store that sells it as an aquarium decoration should not cause this problem as these items are all pre-determined to be safe for use in aquariums.

I have lava rock in my cichlid tanks and also used pieces of landscaping lava rock (the kind you can get at a garden center) in community tanks, without ever any such problem. I tried several combinations of "rust" and "lava rock" without any web results that would indicate that others have experienced rust due to their aquascaping with lava rock.

Hmm, it is hard to imagine rust on a filter in the first place. The only part that is usually metal is the impeller rod (the part under the propeller). Is this where you found the rust? Unless it caused your filter to stop working, I wouldn't assume the rust was why your fish died.

Instead, I recommend you purchase a test kit and test your water. You can have your local fish store test your water for you, but ask for specific readings. Write them down and consider whether water quality wasn't perhaps the issue.

What kind of fish died? Some fish are naturally more sensitive, some need a longer acclimation period or require just the right water parameters. If your tank is new then it may not be fully matured in its cycling. A healthy, cycled tank will have 0 ppm of nitrite and ammonia, always. This is essential to the health of your fish! Any detectable nitrite or ammonia is toxic. Nitrates are the end product of the nitrogen cycle. Nitrate readings should always be under 20 ppm. Levels consistently over 40 ppm will likely lead to health problems for your tank inhabitants.

Just some additional information you might already know...

If your filters are disposable, they should be replaced every week. If they are reusable, they should be rinsed weekly with water from your aquarium. The filter itself should be broken down and cleaned every month.

At least a 10% water change weekly is necessary to replace trace elements and restore electrolytes to your water. But most importantly to dilute wastes. Even if your water levels are acceptable, replace at least 10% of your water a week.

After you test your water, feel free to write back with the readings and a description of your weekly maintenance, and we will re-evaluate the causes. Without these elements, I would just guess that environmental factors were at play and you will have better luck next time. If you do write back, also include the kinds of fish that you lost.

Good luck! Happy new year to you.

Nicole