1. Hi Ian,

    Big fan of your articles! I’m unfortunately another Petco customer who bought a starter 10 gallon kit.
    I’m only about two weeks into a fish less cycle and have just detected nitrites. My existing filter only uses a cartridge and does not have room for ceramic rings.

    I’ve decided to upgrade to an aqua clear filter to set up a proper filtering process – course – fine – rings. My question is, is it best to run both filters together until beneficial bacteria has formed in the new filter? Or is there a way to transfer the beneficial bacteria in the existing filter to the new one?


    • Hi Peter,

      Firstly, welcome to the hobby. Don’t sweat it, unfortunately this is how most beginners are introduced to the cycle. It definitely gets easier from here. Based on the path you have decided to take it sounds like you already have a good understanding of the direction to head.

      If it’s a filter with a cartridge, the beneficial bacteria should live in the white fluffy stuff on the cartridge. Generally, you would cut this off with a pair of scissors and lay it on top of your ceramic rings for a month. However, since you have *just* begun to see nitrites, you may want to run both at the same time before doing this, since at this stage your cycle will likely take a step back or pause. It’s entirely up to you, If I was in your position I would cut the fluffy stuff off now for the sake of not having to run two filters and getting the transition out of the way earlier. However, I can understand that seeing the cycle stall or restart can be incredibly discouraging to a beginner who has already waited two weeks to see signs of movement. Whichever path you choose, the tank will eventually cycle just fine.

      • That makes sense to me. I’ll go ahead and replace the filter, but transfer over the white fluffy stuff from the cartridge.

        Thank you so much for your help!

  2. I read your articles on mechanical, bio, and chemical filters and am wondering now how to properly set up a filter for a small tank?

    I inherited a 5gal tank (and three mollies) from a friend and it has a little filter/pump hanging at the top of the tank that you drop activated charcoal filter cartridges into. It seems to be working fine but having to replace the filters every two weeks is very annoying. I’m not sure if I can reuse the filters and have been buying new ones (it’s not too terribly expensive but again it’s annoying). I’m realizing this may not be great for my tank as it could be killing off the beneficial bacteria.

    I just changed over to the eco-complete substrate as I have 3 plants in there that weren’t doing too great and I was told to keep an eye on the ammonia levels afterwards. I’m a little concerned now that I won’t have the necessary bacteria in the tank to manage any increase in ammonia.

    It’s a cheap tank setup and I’d rather not change to a new tank but I want to make sure I’m filtering out the tank correctly (and caring for filters right too!).

    How should I be filtering my tank and how do you set it up?

    Thank you for your help and all the knowledge you share on this site!

    • Hi Jacqueline,

      Unfortunately, those disposable filters are somewhat of a scam, when you throw them out, you are also disposing of the good bacteria that clings to the filter media. You are absolutely correct in your thinking here. They are also very expensive to replace when the truth is, great filtration is dirt cheap (once you have the filter, that is) all you really need is a piece of sponge and ceramic rings. If you want super crystal clear water, by filter floss (50um) in bulk. The order is coarse sponge -> filter floss (if applicable) -> ceramic rings) if your current filter doesn’t allow this, grab an aquaclear HOB filter, they have room for you to set all this up yourself without relying on disposable cartridges.

      If you want more info on cycling and the importance of these bacteria, check out this guide:

      My first advice if you have not already would be to run out and grab an aquarium test kit (I recommend the API master test kit, it has everything you need and is the cheapest by far) this was you can monitor your tank to make sure the beneficial bacteria are doing their job.

  3. Hello there,

    All of the levels in my well water I’m using for fresh-water fish are normal. However, we have a high level of iron in our water and every fish we have bought dies within a day (Glofish). I am going to try some goldfish today but am weary. Do you have any recommendations on a filter that can possibly take out iron? Thanks!

    Sincerely- Heidi

    • Hi Heidi,

      Stop adding fish to your tank expecting different results. You are going to kill your goldfish too. If iron is the cause, you will need to remove it before adding the water to your tank. You can do this by changing water sources or by using an RO filter and remineralizing water before adding it. Neither option is as affordable as tapwater, however there are some locations where fish are not viable without taking these extra steps.

    • Hi Lex,

      If your water parameters look normal, and their are no warning signs in your tank, then you might not need chemical filtration at all. However, if you want to remove something from your tank that your other two filters cannot, then a chemical filter might be just what you need.

Leave a Reply

Your comment will appear after it is approved by our staff. For more information, please refer to our Comment Policy.

Your email address will not be published. Required fields are marked *