# upgrading to 90 or 120 gallon from 65. Some questions



## arenaranger (Jun 5, 2011)

Hello everyone, 

I am new to posting here but have been lurking around for a few years now. I am in the process of upgrading my tank, however, I am not sure how big to go or how big I CAN go.

I currently have a 65 gallon aquarium that is doing well. I would like to upgrade to a 120/125 but am not sure if the weight of it can be supported by the floor. I live in a townhome and my aquarium is station in my living along an inside wall which is actually the dividing wall between us and the neighbours. The aquarium will be placed on the main floor with an unfinished basement underneath. the aquarium will be running perpendicular to the floor joists rather than running parallel with them so when the aquarium is stationed, it will cover across quite a few of the joists. 

I would really love to jump up to the 120 size but am nervous that it will go through the floor and that is why I am thinking 90 gallon. FWIW the 65 gallon seems very sturdy on the floor now. 

So, I am looking for thoughts, expertise etc. regarding these two tanks. 

Positives/negatives of these larger size tanks. 

Any thoughts or help is really appreciated.

Thanks, Kevin


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## chenowethpm (Jan 8, 2014)

For the tank, go with the largest footprint so the weight is more evenly distributed. Does the wall extend down through the basement. I'd say you're good because it's going to be perpendicular to the floor joists.


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## jrman83 (Jul 9, 2010)

Usually as long as you are on an outer wall or load bearing wall, you would be okay. A 125g, although about 1400lbs is not too bad.


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## jccaclimber2 (May 6, 2012)

I'm not sure how you decorate, but I would strongly consider a 120 over a 125 just because the extra depth (front to back) makes decoration MUCH easier.


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## Botiadancer (Dec 30, 2013)

"...unused basement..."

Am I the only one with the words, "FISH ROOM!!!" screaming in my ears?

If you're nervous and the basement is yours, add some extra supports. Are the joists exposed? Are you in earthquake country?

FISH ROOM!!!! FISH ROOM!!!!!!!!!!! FISH ROOOOOOOOOOOOOOM!!!!!!!!


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## henningc (Apr 17, 2013)

I'd go with the largest width. With tanks like that you can make hiiden areas that will support life in the tank. You can hide PVC caves behind driftwood or rock structures toward the back or put a large sponge filter back there. Depending on what is going to live in the tank, it can be areal advantage. When people work with the larger Cherax crayfish, some get 12", they need some place to hide out when they molt. You can make a PVC tunnel under a rock structure for them or tunnel ways for your bottom dwellers to hide and pop up somewhere else.


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## arenaranger (Jun 5, 2011)

Soooo, I have been doing some more research and I have actually come across so info that may be very interesting to others. 

When doing the calculations regarding the pounds per square foot on the floor when the tank is full I discovered that the 120 gallon aquariums is lighter than the 90 gallon by about 20-30lbs.

120 gallon square footage is 6ft x 1.5ft = 9sq ft. approximate weight of aquarium when full is 1400lbs according to some research I did. 

So, 1400 lbs / 9sq ft. = 155.5 pounds per square foot on the floor.

A 90 gallon is 4ft x 1.5 ft = 6sq ft. The 90 gallon when full is appro 1050 lbs.

So, 1050 / 6 = 175lbs per sq. ft

I currently have a 65 gallon like I said earlier. 3ft x 1.5ft = 4.5sq ft.
A full 65 gallon tank is approx. 772lbs. 
772 / 4.5 = 171.5lbs per sq. ft. 

My conclusion is this, given that I have a 65 gallon right now that I have no problems with regarding floor sagging or bounciness, I am thinking that in order to go to a tank that is exactly twice as long (and almost double the weight) as the one I currently have but keeping in mind that I am going to double the floor joists that it sits on therefore spreading the weight, I don't see any issue with upgrading to a 120. The weight is very well spread out and evenly distributed and is actually 16lbs lighter per sq. ft. than what I am currently running. 

I also work with a building official who told me that a floor in my home would be built to withstand 40lbs per sq. ft. at its weakest point. I am placing my tank is near its strongest point. He also said to block together the floor joists underneath the tank to avoid twisting etc. like this-_-_-_-_-_-_ between the joists. He said by blocking the joists, it will make it MUCH stronger as well. 

Am I missing something here or does it seem like I should have really no problem upgrading to a 120 gallon tank given what I can see. 

Please challenge this if you can. I am not saying this is correct nor the best way to calculate this kind of stuff.

The other thing I should mention is this is planned to be installed on a stand with a completely flat base on the floor. Something like a stingray stand doubled up from Big Als.


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## chenowethpm (Jan 8, 2014)

Exactly, the bigger the footprint of the tank/stand, the more the weight is distributed over a larger area.


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## coralbandit (Jul 29, 2012)

There are 4x2 120 g tanks also?I love my 180(6x2x2) but do think the two 120's(4x2x2) I have are the most effiecient use of space.I would strongly recommend looking into a 2' wide tank like jc mentioned for better decorating.


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## arenaranger (Jun 5, 2011)

I would really like to go to a 2' wide tank. However I must stick with 18" or it will stick out past the sliding porch door. 

Thanks to everyone who providing their thoughts.


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## arenaranger (Jun 5, 2011)

has anyone actually heard of an aquarium breaking through and crashing to the floor below on any of these standard size homeowner tanks? 120 would be the biggest I am familiar with that I would call standard.


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## Botiadancer (Dec 30, 2013)

First I must say:

I am NOT building engineer, structural engineer, or anything related to any field that actually knows the physics or code of housing structures.

Now:

I may be mistaken, but when they talk about 40lbs/ft, they are referring to the load the entire floor would take. So a 12x12 room, with 144 sq ft, can take a load of 144 x 40 = 5760 pounds. Obviously, if you put it on the head of a pin, it will sink right through the floor. Each room would be measured separately as it has its own supports. I'm sure shared supporting walls are factored into this, as they may be made stronger in the first place.
You standing on a floor far exceeds the 40lbs/ft, but that is a moving (active?) load, not a static load. (no, I have no idea what that means, it just always gets mentioned)
Bathrooms don't seem to look any different than other rooms when viewed underneath, (the tub is supported, but on normal joists) but maybe the short spans is the reason for this. Think about it - 50 gallons of water, 2 humans *cough cough* splashing about; that's one heck of a load on the floor.

Uarujoey's site (diyfishkeepers) has many threads on this topic, as does monsterfishkeepers.com. I believe some of the threads are from structural engineers of some type, so it is very good info. I was much more relaxed after reading those threads - though I only have a 60g, among other smaller tanks-and zillions of books on a 2nd floor apt. I'll try and find some links.

Edit-Found one
http://african-cichlid.com/Structure.htm

And once again.... UNUSED BASEMENT = FISHROOM
Its listed in the code of ethics for all aquarium keepers. Not converting it into such means loss of fish keeping privileges and all fish and equipment must be given away.

*DIBS!!!*


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## arenaranger (Jun 5, 2011)

My basement is a complete woodshop. No room for fishroom. just building aquarium stands instead...


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## jccaclimber2 (May 6, 2012)

arenaranger said:


> Soooo, I have been doing some more research and I have actually come across so info that may be very interesting to others.
> 
> When doing the calculations regarding the pounds per square foot on the floor when the tank is full I discovered that the 120 gallon aquariums is lighter than the 90 gallon by about 20-30lbs.


Lets not mix up weight (term lighter) and pressure. Correct that the floor loading is less. This of course assumes your stand uniformly distributes the load, which may or may not be the case. If all of that 6' of tank (a 125 gallon as my example) ends up on the same beam before it gets to a column then being spread over 6' doesn't matter. If it goes to more beams as a result, it will help.


arenaranger said:


> 120 gallon square footage is 6ft x 1.5ft = 9sq ft. approximate weight of aquarium when full is 1400lbs according to some research I did.


A reasonable estimate.


arenaranger said:


> So, 1400 lbs / 9sq ft. = 155.5 pounds per square foot on the floor.
> 
> A 90 gallon is 4ft x 1.5 ft = 6sq ft. The 90 gallon when full is appro 1050 lbs.
> 
> ...


This is just going to help out the actual floor boards. For joist load you would need to look at load per joist in combination with the distance the joist is from its supports.


arenaranger said:


> My conclusion is this, given that I have a 65 gallon right now that I have no problems with regarding floor sagging or bounciness, I am thinking that in order to go to a tank that is exactly twice as long (and almost double the weight) as the one I currently have but keeping in mind that I am going to double the floor joists that it sits on therefore spreading the weight, I don't see any issue with upgrading to a 120. The weight is very well spread out and evenly distributed and is actually 16lbs lighter per sq. ft. than what I am currently running.


While your conclusion that it will be fine may be correct, you should consider the following:
1) Depending on your floor construction there may be some shared loading with the surrounding joists, so you might not actually be "doubling" the number of support beams.
2) This will still change the loading on whatever holds those beams.


arenaranger said:


> I also work with a building official who told me that a floor in my home would be built to withstand 40lbs per sq. ft. at its weakest point.


Transient live loading is not equivalent to long term static loading and should not be directly compared.


arenaranger said:


> I am placing my tank is near its strongest point. He also said to block together the floor joists underneath the tank to avoid twisting etc. like this-_-_-_-_-_-_ between the joists. He said by blocking the joists, it will make it MUCH stronger as well.


True.


arenaranger said:


> Am I missing something here or does it seem like I should have really no problem upgrading to a 120 gallon tank given what I can see.
> 
> Please challenge this if you can. I am not saying this is correct nor the best way to calculate this kind of stuff.


Challenged above. Ultimately if you are against a supporting wall it will likely be ok. If you aren't sure level it and measure height (empty) at the corners with a water level relative to something fixed across the room. Fill it and remeasure, then check again in a week, month, etc. If it isn't moving then you should be ok. A pair of steel columns on proper cement footers directly underneath (distributed with a pair of 2x8s) would also be a big help. This is how I did my 300.


arenaranger said:


> The other thing I should mention is this is planned to be installed on a stand with a completely flat base on the floor. Something like a stingray stand doubled up from Big Als.


I'm not familiar with the Big Al's stand. Flat floor stands still generally put all of their load around the outer edges, with emphasis at the corners depending on construction, door openings, etc.



arenaranger said:


> has anyone actually heard of an aquarium breaking through and crashing to the floor below on any of these standard size homeowner tanks? 120 would be the biggest I am familiar with that I would call standard.


A 6 foot tank is normally referred to as a 125, with a 120 being the 4 and occasionally 5 foot versions. Nominal dimensions on a 125 being close to 6' long x 18" deep x 23" tall.



Botiadancer said:


> First I must say:
> I am NOT building engineer, structural engineer, or anything related to any field that actually knows the physics or code of housing structures.
> 
> Now:
> ...


Live loads are different than static loads. The issue I mentioned above though is slightly different. Holding a static load briefly (three big guys standing next to each other for a football game) vs. a long period of time (bookshelf for 10 years) will not have the same end result. There is some bending over time that wood sustains. Point loading such as a pin would also dent the floorboards before reaching that high a loading. The good news is that sturctures tend to have a decent safety factor to compensate for knots in wood, etc.


Botiadancer said:


> Bathrooms don't seem to look any different than other rooms when viewed underneath, (the tub is supported, but on normal joists) but maybe the short spans is the reason for this. Think about it - 50 gallons of water, 2 humans *cough cough* splashing about; that's one heck of a load on the floor.


The humans may well be standing at the same end too, a higher load at that end. If you distribute that weight across the entire tub, it is still probably a low per joist load, particularly compared with an aquarium of the same dimensions.


Botiadancer said:


> Uarujoey's site (diyfishkeepers) has many threads on this topic, as does monsterfishkeepers.com. I believe some of the threads are from structural engineers of some type, so it is very good info. I was much more relaxed after reading those threads - though I only have a 60g, among other smaller tanks-and zillions of books on a 2nd floor apt. I'll try and find some links.
> 
> Edit-Found one
> http://african-cichlid.com/Structure.htm
> ...


Unused basement = RO water storage system in my case as I prefer to keep my fish in the living space where I see them. I can certainly see the appeal for breeding projects though.

Ultimately you are probably ok with a 6' 125 sitting orthogonal to the joists along a supporting wall. If you want to be sure, check level. Also do yourself an (aesthetic) favor and level it before you fill it.


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## Botiadancer (Dec 30, 2013)

This jccaclimber2 character seems to know his stuff! Thanks for clarifying my unasked questions and fixing my mistakes!

"My basement is a complete woodshop. No room for fishroom. just building aquarium stands instead... "
"Unused basement = RO water storage system"
- the only acceptable alternatives.


I love learning new things!!!


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