Converting 90g Tank To 150g Tank

  1. S

    Socalfishguy13 New Member Member

    Hello all, first time poster here and hoping for some advice.

    I currently have a 90 gallon tank that has been stocked with various fish for about 2 years. I would like to upgrade to a 150 gallon tank and would like to know the easiest way to go about it.

    The equipment I have was all received used, so the tank, canister filter, lighting equipment and heater are all about 3 - 5 years old though they seem to still be in good working order.

    When I get the new tank I plan to change my substrate from rock to gravel. The fake plants, rocks, etc and other items inside the tank I plan to keep and perhaps just add some new ones to fill out the new tank.

    My questions are these:

    Do I need to let the new tank cycle if I plan to transfer a majority of my tanks current water into the new tank.

    If I get a new filter but use the current media within my old filter, is that acceptable?

    And any other suggestions to any questions I don't know to ask would be helpful as well.

    Thank you!!
     
  2. Goldiemom

    Goldiemom Well Known Member Member

    The water has very little bacteria in it so using same water won’t do any good. However, if you take the old filter media and stuff it in the new filter, it should give you an automatic cycle. That or you can run both filters for a couple of weeks. Good luck!
     
  3. CraniumRex

    CraniumRex Well Known Member Member

    Agreed, although if your tank has been running for 2 years I would suggest using part or all of the water if you plan on moving the existing fish to the new tank. It would be the equivalent of a 40% water change to use most of all of the 90 gallons and add roughly 60.

    Opinions differ but I happen to believe that TDS shock to your fish is a possibility if you don’t know the current tank’s level versus fresh tap water.

    In theory if you are moving the substrate, decor, and filter media over and not adding any fish right away you should get an instant cycle but I’d caution doing testing for the first while to ensure you don’t get a mini-cycle. Theory is one thing but changing anything in a closed system well, it’s not impossible.
     
  4. mattgirl

    mattgirl Fishlore VIP Member

    I agree with @CraniumRex and would just transfer everything over to the bigger tank. As @Goldiemom pointed out there is no bacteria in the water but it is the water your fish and the bacteria are used to so I always recommend using as much of it as you can.

    I would take the fish out of the 90 gallon and house them in some kind of container filled with water from their original tank. (I would use something like a sterlite storage container) Run your filter/s on that container while you transfer everything else over to the bigger tank. Be sure to keep everything in tank water to preserve the bacteria that has established over the years. Most of the bacteria lives on your filter media but some lives on every thing else in the tank too.

    If done this way neither your fish nor your cycle (bacteria) will know that they have moved. It will just seem like a normal water change to them.