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Pros and Cons – Considering Size When Purchasing an Aquarium



This is more than just the actual size of the aquarium. Obviously, a 180 gallon tank would make a poor desktop aquarium just as a 10 gallon tank would be an inadequate room divider. Measurements aside, it is important to also consider how much weight the floor can support, particularly if you’re considering a large tank on any floor with open space beneath. In the 19th century house I live in, I’m fairly certain that a large tank would go straight through the floor and end up in the basement. Some apartment complexes won’t even allow larger aquariums, especially on upper stories. A gallon of water weighs a little over 8 lbs, so water weight in addition to substrate and ornamentation can spell disaster on a weak floor. Saltwater aquariums are also generally going to be heavier than freshwater aquariums – the salt in the water and live rock used in most tanks increases the weight.


In terms of the supplies for the tank alone, a larger tank will usually cost more than a smaller one. Larger tanks will need more substrate, decorations, lighting, filtration and livestock to get the same look as a smaller tank. For saltwater aquariums, a larger tank is going to require more salt mix than a smaller tank. Cost of the aquarium itself and the equipment can vary. While you can generally expect the cost to go up proportionally with the size of the equipment, there are a lot of high-end, high-tech or just plain fancy nano-aquariums and equipment that are becoming hot items in the trade.


Most new aquarists start out with smaller aquarium because they seem easier. In terms of stability and the chemistry of the aquarium, the opposite is actually true. Larger bodies of water are actually far more stable. Imagine adding a cup of food coloring to a kiddie pool, then adding an identical cup of dye to a fullsize swimming pool. The kiddie pool will obviously be much darker in color and will show evidence of that dye far more than the swimming pool will. If both pools are outside on a hot summer day, the kiddie pool will also likely be much warmer than the larger pool (and will freeze much faster in the winter). Aquariums aren’t too different. With all other relative factors equal, the water chemistry in a small aquarium will fluctuate and be harder to stabilize than in a larger system.


This can be tied in closely with stability. A smaller aquarium can take more cleaning and maintenance to keep it stable, but a 10% water change in a 10-gallon aquarium (1 gallon) versus a 100 gallon aquarium (10 gallons) is obviously going to be very different.  That same water change may need to happen more often in the smaller tank to get rid of the waste though, but the water change in the larger tank may be much more work. The filtration used in small and larger aquariums is generally different as well. Most larger filtration systems like wet/dry systems can actually take less maintenance than smaller canister or power filters.

Stocking the Aquarium

What fish or invertebrates or plants do you want in your aquarium? Keep in mind that a smaller tank will limit your choices. Many popular aquarium fish will grow too large and/or aggressive for smaller tanks, while others stay very small and may get lost in big tanks. Fish and inverts may have food requirements that can’t be filled if an aquarium that is too small or too large. Some have territory requirements that can cause problems in smaller tanks. Some animlas may be sensitive to changes in water chemistry in the aquarium, while some may require changes in chemistry or temperature to trigger breeding, if you are trying to breed them (see the tie-in there?). This is one of those age-old, chicken-or-the-egg questions – do you buy the aquarium for the livestock you want to put in it, or do you buy livestock for the aquarium that you bought?

These are just a few of the main factors that may effect an aquarist’s aquarium choices. While your own aquarium choice may force you to sacrifice ease for one of the other factors, its important to be aware of each factor before you buy a tank.


  1. avatar

    I just bought a 44 gallon tank for my “common algae eater”. Al, not creative in name, is now about 8″ in a 15 gallon tank and was told he keeps getting velvet and becoming slow as he’s running out of room and is stressed. I have a fresh water tank. My new tank is a corner tank.

    Here is my dilemma! I really know little and until now have done little research on keeping my fish healthy. The second dilemma is I live alone, so it’s all up to me. I’ve done all my water changes by the hauling method. What can I do to make this less back breaking? Can I just add a second filter to my existing filter and the same thing with heaters?

    My next question is how many fish can I keep in this tank? I really like fancy tail guppies, but would like a little variety and my LFS doesn’t seem to carry them.

    My last question is it safe to make arches and caves with quickcrete and stone. I’ve already learned not to put our Michigan rock collection in the aquarium. I have a collection of red jasper we brought back from Arkansas Diamond Park.

    One last last question. Where is a budget resource for the hardware ie. heaters, filters?

    That’s all the questions. Really!! Any pointers would be great and not the pros and cons on each type. That’s confused me even more now.


  2. avatar

    Hi Theresa, It might be best for you to give us a call (717-299-5691 or 888-842-8738) and discuss your tank with one of our aquatics staff so we can make sure we cover all of your questions but I’ll try to touch on them here.

    I’m not sure what type of “common algae eater” you have from your comment so it is difficult to address specifically. I’m assuming that it might be a Trinidad Pleco? If it is, even the new 44-gallon will be too small for it. We have a number of articles on our online Aquatic Article Archive to help you do your research for your new tank.

    For your maintenance concerns, a water changer like this one from Aqueon may help you out if your tank is close enough to a sink (their longest one is 50ft). Depending on your type of floor, you can also try a wheeled bucket or cart. Without knowing what type of heaters or filters you have, it is difficult to say if adding another one to it will be enough for your new tank.

    How many fish you can keep depends on how well-filtered and heated the tank is. Plecos, especially larger ones, can produce a lot of waste so you need to make sure the tank is well-filtered to keep the water quality good. Plecos and other tropical fish like guppies will need water temperature that is consistent and about 75-80 degrees at all times. Other fish that could go with a pleco would be fish like tetras, danios, rasboras, rainbowfish, barbs, gouramis, platies, mollies or swordtails, just to start. Again, if it is a Trinidad Pleco that you have, even your new tank won’t be large enough down the road.

    As it sounds like you’ve already learned, not all stones can be used in an aquarium. Some will raise or even lower the pH and water hardness and I would never recommend using a stone from an unknown source like a backyard or park since it is impossible to tell what it might have been exposed to. You need to make sure that whatever stone you use is inert (won’t affect the water quality), free from pollutants and doesn’t have any shark edges that might harm your fish. Using material like Quikrete is risky since the materials used in it may affect the water by raising the pH, hardness and alkalinity.

    I’m not sure what kind of “budget resource” you are looking for. There are lots of different options and price ranges for equipment like heaters and filters so you can choose what works for you and your budget. We have additional information in our Article Archive on choosing an aquarium filter, the best aquarium filters, choosing fish tank heaters and more.

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!).