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How to Upgrade Your Aquarium

I recently blogged on some tips and techniques for moving an aquarium, but what if you just want a larger tank? This was a question asked after that blog was posted. Some people start with a small tank for “simplicity” and get hooked enough to want to expand. Others want to switch the type of livestock they are keeping or have fish that have outgrown their existing tank. No matter your reason, many of the considerations and techniques that go into moving an aquarium apply to upgrading as well.

The “easiest” upgrade scenario would obviously be one in which the new tank is being set up in any location OTHER than where the existing tank already stands and has all new “stuff” in it (meaning substrate, rockwork, decoration, filter, etc.); you can be a bit more leisurely with this switch. On the other end of the upgrade-spectrum, you may be putting the new tank in the same place as the old one with some of the same substrate, decorations and equipment and will need to be more expedient with the transfer.

Whether freshwater or saltwater and in any situation, the new aquarium will need to “cycle” through the Nitrogen Cycle as we’ve discussed before and will take some time to become re-established. You can help this along in several ways – by using water and filter media from the existing aquarium, transferring substrate and decorations, or by setting up the new aquarium and allowing it to cycle before tearing down the old one (only practical if the new tank is going somewhere OTHER than where the existing tank already stands).

If the new tank is going in a new location, I would recommend a gradual upgrade. Get the tank set up and running, “seed” some biological filter media in the old tank for a few weeks and add it to the new one, even use water change “waste” water from the old tank in the new one (For example, let’s say you have a 20-gallon aquarium and are upgrading to a 40-gallon in another room. If you remove 5 gallons from Tank 1 in a water change, use this to replace 5 gallons out of Tank 2 instead of fresh, clean water). Obviously, not something you’d want to do if the water change water is filthy or of very poor quality, but can be done with “cleaner” dirty water, if you haven’t gravel-siphoned, for example. Once the new tank is at least fairly established, you can start gradually moving the fish and other livestock from the old aquarium into the new, larger tank.

If you are putting the new aquarium where the old one was, it is distinctly more complicated and is definitely a project for some weekend day (one of those days that you can bribe some friends with pizza to come help you). My tips are going to be easy. Remember that blog on how to move an aquarium? It all applies. You may not be moving it to a new house, but since you need to get the old aquarium out of the way, you will need to use the same methods to get it broken down and out of the way before you can move the new one into its place.

A note on floor weight loads:

The first and most important thing to consider for any new aquarium or upgrade is the weight limit on the floor where the aquarium will be placed. However, actually determining this weight is obviously not covered…simply because I’m a biologist and not a structural engineer. Obviously, a cement floor on the bottom level of a building can hold more than a third floor apartment but how much that third floor/first floor/basement/two-hundred-year-old floor can withstand is going to vary with the structure itself and you should consult a professional. To get you started on what to consider and how to consider it, I would recommend visiting this excellent article by Kevin Bauman, posted on Cichlid-Forum.com.

If you have any questions about your specific upgrade or have an idea for a topic you’d like us to cover next (or want suggestions on what to put into your new, larger aquarium!), feel free to let us know!




  1. avatar

    Hello I have a few cory catfish and a couple algae eaters in a 10 gallon tank which I’m upgrading to a 40 gallon. I have the 40 gallon set up and have transferred a few of the old decoration and put some of the old gravel in a stocking and placed it in there as well. I also used some quick start, I plan to transfer the old filter as well for a few weeks. My question is when can I tranfer my fish to the 40 gallon and should I transfer the old water and when should I transfer the filter? I really need help with this cause its really stressing me. Also I put about 10 gallons of RO water along with tap water in the 40 gallon and I have another 5 gallons in a bucket just in case, if that makes any difference. Thanks in advance

  2. avatar

    sorry for the delayed response..the transfer of the filter with established bio media and even dirty cartridges should provide plenty of bio fodder to get the tank started. You’ll still go through a cycle, but hopefully it will be mild.

  3. avatar

    I am upgrading my tank from a 37t saltwater tank to a 80 gallon reef ready tank. I plan on putting it in the same location as my current stand. I plan on putting my fish and possibly 20 gallons of my water in the same tub with my live rocks. The substrate will be moved over to the new tank with 2 more 20lbs bags. I plan on using my return pump to pump the water into my tub. I will have the 40 gallons 2 bags of substrate in the new tank. After I get the fish into the tub I will remove the substrate from the old tank and place it into the new one. After that, I will use the rest of the water to place it into the new tank and hopefully speed up the cycling process. I plan on putting the other 20 gallons back into the new tank as well. What are your suggestions?

  4. avatar

    Hi James, it sounds like you have a good plan going already, and hopefully you’ll minimize the cycle in the new tank. Be sure to test regularly and practice patience in the few weeks after the upgrade to make the transition successful!

  5. avatar

    Hi, there are some good ideas here but I have already asked for a new slightly bigger aquarium (55 to hopefully 60 gallons) for Christmas. And it will be placed in the same locations as the one I have up now. I already have angels, sharks and one flower horn and several plants. Something I really am concerned about is what would I use to empty the tank water into. I do not know what materials are in a large plastic trashcan and am concerned that it may be toxic to the fish and water that I plan to reuse in the new tank. In other words, could i purchase a large plastic trashcan and clean it out with running water and use that as my fish and water holder. I also plan to use a different substrate as I am tired of the sand.
    Any help with the “toxic” issue would be greatly appreciated.

  6. avatar

    wash the trash can thouroughly, but the plastic or pvc should be inert and toxicity should not be a concern

  7. avatar

    I am upgrading to a larger tank soon.
    As I was reading your answers to Candy’s questions, I found myself wanting to know about using a different substrate?
    I will be using most all of the decorations, plants and filter system from the old tank.
    I am just worried over not using the old substrate, but it is ugly and it’s time for a change.
    This tank will have a couple of “old” fish from the old tank and I will be getting new ones at a later date.
    I want to make this change over in 1 days time if it is possible.
    Thank you!

  8. avatar

    Hello Laura, You can certainly change to a new substrate as you move to a new tank. Since a lot of the beneficial bacteria that stabilizes a tank lives in the substrate, you are certainly more likely to have to re-cycle your tank through the Nitrogen Cycle again when it is set back up. To help with this, you can put some extra biological filtration media in your tank for a few weeks prior to the move like we discussed in this blog and in the How To Move Your Aquarium blog.

  9. avatar

    I have a 55 gallon tank that has been set up for almost a year. When I set that tank up i had a bad transition and lost several fish. I have a new 55 gallon tank with a new 3d background. I would like to know if i moved all or as much of the water into the new tank along with the biofilter that is well established, will I be able to move the fish over the same day?

  10. avatar

    Hello Shaun, Moving as much of the bacterial population as possible will certainly help your new tank become established faster but it will still need to go through its natural cycling process. As long as all of your equipment is working correctly, you should be able to move the fish but you will still need to monitor the tank and water chemistry carefully.

  11. avatar

    I got a goldfish and was told to put it in a small tank (0.5 gallons but I bought a 1.5 gallon instead). However the fish started turning black and I found out it had ammonia burns (ammonia levels were at the highest danger level) and that it needs a larger tank, 10 gallons instead. So now I have a 10 gallon tank (doesn’t have a filter) and don’t know how to safely transfer this fish over to a much larger tank. Should I keep all of the old water since it’s only 1.5 gallons or discard all that water since it wasn’t safe. Since there is no filter, will it be safe to introduce it to the tank within a day? Is a filter required and can I introduce it at a later time?

  12. avatar

    Hello Kangaroo Mama, Goldfish grow up to 6-8 inches for fancy varieties and 10-12 inches or more for the common Comet Goldfish (including those sold as “feeder goldfish”). A 10-gallon tank is still too small for goldfish and with the very high levels of waste that goldfish produce, they should only be in a well-filtered aquarium. There will still be ammonia issues in an aquarium that small. I would recommend reading through our blogs “The Best Aquarium Filters for Goldfish” and “How to Care for Carnival Fish” to start with for some basic information on the requirements for goldfish.

  13. avatar

    Thank you for your reply. I plan on getting a bigger tank but can’t afford it just yet (went from a $20 tank to a $100+) but a friend had a 10 gallon right now we can use, just no filter. I didn’t want to buy a filter for a 10 gallon tank and then have to buy another one again when we get a 20 gallon. Or are there some filters that we can get that will fit in either tanks that we could get? Right now I have treated about 7 gallons of water in the new tank and was planning on using all of the old water from the original small tank to introduce the fish into the new aquarium. Not sure if that’s the best course of action.

  14. avatar

    Hello Kangaroo Mama, A 20-gallon will still be too small for goldfish. Fancy goldfish like fantails would need at least a very well-filtered 30-gallon and Comet Goldfish would need much larger still. The ratings on power filters are also very conservative and for lightly stocked tanks. For goldfish, you will need to get a filter rated for a larger tank than you have. For example, a 20-gallon goldfish tank would need a filter rated for at least 45-gallons or larger. I would recommend reading through the links that I sent you in the first reply for some information on caring for goldfish.

  15. avatar

    Hi. I have a 5 gallon saltwater aquarium and want to move up to a 14 gallon tank. I have corals, two fish, live rock, live sand and many snails in my 5 gallon. I want to put the new tank in the same place as the 5 gallon but am fearful of losing my live creatures if I move them over to the new tank with new rock and extra sand. How do I make the switch? I have coral on every part of my live rock so if I moved it over, the corals may not respond well to the new tank and die. 🙁 What steps do you suggest? This is in my classroom and would need to be done on a weekend.

  16. avatar

    Hi Laura, The steps I would recommend would be those in this blog and in the blog entry “How to Move Your Aquarium” that is mentioned here. If you are increasing the amount of substrate, I would recommend putting the old substrate on top of the new substrate so anything in it is not suffocated and will seed the new substrate better. As we discussed in this entry, your newly upgraded tank will still need to go through a cycling process but if you save as much of the water, substrate and biological media as possible, you should be able to reduce the impact of it as much as possible.

  17. avatar

    A friend gave me a 5 gallon tank a couple years ago and I bought a black molly and goldfish at the local pet store. They have grown to like 6 inches each, they have an aerator and filter and quite content but everyone keeps saying they need a bigger tank so I bought a 10 gallon but am so scared to transfer them over to it. Should i just put all the gravel and filter and aerator from old tank. I have only used tap water when I change their water every 4 days and have never had a problem with them. I bought 2 new bags of gravel for 10 gallon, do i just rinse it before putting in new tank? Any advise will be appreciated. Thanks

  18. avatar

    Hi Maria, Even a 10-gallon is far too small for a goldfish. Goldfish produce a lot of waste and need a large, very well-filtered aquarium. A fancy goldfish (Telescope, Fantail, Bubble-eye, etc) should have at least a 30-gallon aquarium and a common goldfish (one single tail, usually sold as pond fish or “feeder fish” when very small) would need much larger. If the goldfish alone is already 6 inches, it should be in at least a 30-gallon already. Mollies typically don’t get over about 3 inches in length but if you have 2 6-inch fish already, they will need a much larger tank than 10-gallon. The filter also has to be large enough to handle the waste the goldfish produces; generally, go up at least one or two sizes from the “recommended” tank sizes on the filter since those recommendations are usually for understocked tanks with small fish, not for larger fish like goldfish. I would recommend checking out our articles The Best Aquarium Filters For Goldfish and How To Care For Carnival Fish. Mixing goldfish and tropical fish like mollies is generally risky since tropical fish need higher water temperatures and more pristine conditions than goldfish.

    It owuld be up to you if you wanted to use new gravel in the new tank. You should always rinse new gravel before adding it to the tank to get rid of any dust and debris. If you are using tap water, it should be dechlorinated before use. If your municipality treats with chloramine as well as chlorine, make sure you get a dechlorinator that removes both since not all do. Also, make sure it is the same temperature as your aquarium before adding it.

About Eileen Daub

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Marine Biologist/Aquatic Husbandry Manager I was one of those kids who said "I want to be a marine biologist when I grow up!"....except then I actually became one. After a brief time at the United States Coast Guard Academy, I graduated from Coastal Carolina University in Myrtle Beach, South Carolina in 2004. Since then, I've been a marine biologist at That Fish Place - That Pet Place, along with a Fish Room supervisor, copywriter, livestock inventory controller, livestock mail-order supervisor and other duties here and there. I also spent eight seasons as a professional actress with the Pennsylvania Renaissance Faire and in other local roles. If that isn't bad enough, I'm a proud Crazy Hockey Fan (go Flyers and go Hershey Bears!).