Structural and fish tank placement... need opinions please

[PCguy21]

So ive been calling for 2 hours trying to find a structural engineer. Its hard even finding one and the two i did find.. one gave me help the other wanted money to even give advice on the phone... typical.

Anyway my question is this. I have a 135g 1.2 thick glass tank in my bedroom 3rd level of the house. Its been in that room for 3 years. The first 1 1.2 years i had it perpendicular to the floor joists directly above a load bearing beam. The beam is two 2x12 beams nailed together some kind of orangish wood. The issue with that position is it blocked 80% of my window so i could never really open my blinds and the window to get fresh air and even look outside.. and i had to move my bed in front of the tank so for 1.4 of the tanks length i had to stand on my bed to do any work to the tank.. lol thats kinda dumb. Also the tank was on a steel stand with just 4 legs so even sitting perpendicular weight was all on the ends of 2 joists vs 4 or almost 5 with a wooden stand

So i rearranged my room. I moved the tank parralell to the joists.. The joists are 11 or 12 feet long. Each end left and right sits on load bearing beams.. If the tank is 6 foot long i decided to position it in the center ( against the wall) This way the left and right side of the tank is at most 2 1.2 feet away from the load bearing beams and i making sense ?

My issue was with 4 leggs 1600 lbs is putting alot of direct pressure on the joists under the floor... I figured if i get a wooden stand one made by a manufacture which spreads weight evenly along 6 feet it would be better..

So i got a stand 2 days ago for 40$ in great shape looks brand new actually... The tank is still sitting parrallel to the joinsts.. so basically its sitting on 2 joists length wise. And the joists are 2x10.

The engineer that did help ran calculations and he said im overstressing the joists and its over stressing them more with the new stand then with the 4 legg stand.. That confused me and made no sense.. He said with the new stand its puts even oressure along the 12 foot joist and actually puts more bending pressure on it then with a 4 leg stand... That makes no sense to me.



What do you guys think ? I know 100% without a doubt putting my tabk back against the outside wall specially with the new stand is best because itll be laying directly over top a load bearing beam supporting at least 4 to 5 joists.. Then keeping it length wise on 2 joists.... but still.

Do you guys think itll be ok where it is ? Its been parrallel on 2 joists for over a year and thats with s 4 legg stand.. I figured thr new stand spreading weight evenky along 6 feet was better.. but now im told its worse lol ?

 

[mcgyvr]

There is typically no issue with a tank that size anywhere.. 4 legs or not doesnt matter much...When you get to the 200+ gallon mark you need to start thinking structurally

 

[PCguy21]

Well thats what i was thinking. Specially with the joists only being 11.5 or so feet long. 2x10s i know different grade wood has diff strength.. its some kind of pine. 6 foot tank length wise on 11 feet meanes the tank ends are 2 1/2 feet away from both load bearing beams and the ends of joists ( closer to the end means more strength) plus with my new stand weight is spread evenly.

If ny tank was fine for nearly 2 years parrallel with 4 leggs wouldnt it fine parrallel with a typical wooden stand that spreads the weight better... I just figured logic would mean its actually better eith the wooden stand.

But this engineer i talked too said it was better eith the 4 leg stand because all the weight was 2 1.2 feet away from the end of thr joists.. now its spread in the center and the ends..

But that doesnt make sense to me... maybe im wrong.

 

[mattgumaer]

Not to pick a fight but, you're complaining that one structural engineer won't give you an opinion without being compensated for giving you structural advice, which seems more than a little unfair and, when a second gives you advice for free that is not want you want to hear, you complain about that as well.

As a non-engineer, what you were told about moving from a 4 legged stand to a continuous bottom stand, while perhaps a little counter intuitive makes perfect sense. The joists have the more structural capacity the closer they are to their points of support. Picture jumping up and down right next to a support versus in the middle, equidistant from both support points. You're clearly going to get more stress/deflection when jumping in the middle as compared to jumping right next to a beam supporting the joist.

So, your four legged stand and continuous base stand are both applying the same load to the floor, the difference is how/where that load is distributed. Assuming the tank is centered between the two beams, with the four legged stand puts all of the weight as close to the support beams as possible for that size tank. The continuous stand, in the other hand, distributes some of the weight at the ends (closest to support) but also distributes weight in between, across the entire base, which is further from the supports and, therefore, has less load carrying capacity. So, basically, in moving from a four legged stand to a continuous stand, you're shifting some weight further from the support points at the end of the joists.

Personally, I would start to get nervous about placement issues with any tank over about 75 gallons (right or wrong). If an engineer told me I was over stressing my floor joists by putting a 135 gallon tank parallel to my floor joists, I would listen and figure out how to keep it perpendicular to the joists. You already knew it was better to place it perpendicular. As always, just my two cents.

On a separate note, if the floor flexes and the wooden stand flexes with it, creating a situation where the top of the stand is not in a single, flat, plane (bowed down in the middle), you might also be increasing the chances that your tank will leak. Personally, I think many tank failures people attribute to 'bad tanks' are actually a result of tanks not being placed on very flat surfaces, stressing the tanks. But, I'm no engineer, fish tank, structural or otherwise.

Matt

 

[PCguy21]

Your bottom comment i also though about when i swapped stands. The steel stand was using 3 1.6th steel. In a C channle in a rimmed fashion so the entire bottom rim of the tank was supported. Thats thicker then a pickup trucks frame lol.

So there would never been any flexing in the center. But the wooden stand would flex its only supported in the center and the 4 corners

However i will add. No tank actually needs support in the center. All you need is to support the 4 corners on a rimmed tank. Im not 100% sure if that count towards 6 foot tanks but i do know for smaller tanks its true.

Ya i knew i was shifting weight from left abd right to more like left right abd middle.. but evrrything i readconline says legged stands are the worst you can have..

Uhg this is stressing ne out.. Problem with moving the tank perpendiulcar is my room is only 12 feet long and like 8 feet wide. So i have to put my bed where the tank is now and my tank where my bed is... which blocks my window and will keeo my bed 2 inches away from my tank so i cant open the left doors then...

Bjt ive had it like this before.... uhg. Such a pain lol

 

[mcgyvr]

Stop worrying..
Its fine..

 

[PCguy21]

Yea ill stop lol its been there over a year now.

 

[tkeracer619]

I will say this. You messed up by putting the wood stand in there. Here is the thing, steel stands typically don't flex. Aquariums need to be in plane. If the tank twists, it will fail. Wood stands twist and fully require the floor to be stable. A steel stand if built properly will keep the tank from twisting.

By going parallel to the joists as the floor flexes, on the wood stand, the tank twists. Put it back on the steel stand, because as the floor flexes, the tank will just go out of level, but it will still be in plane (as long as the stand is strong).

I'm not a structural engineer but am an engineer and have done many FEA runs on aquariums, floors, and their stands.

 

[PCguy21]

Wouldnt i be able to see if its twisting by using a level though and looking at the water level ? Like checking the level front to back side to side. It would show if a corner is off level or not. Which it was with the steel stsnd and wooden stand i had to shim both to get the tank water level even from left to right. And front to back on each left and right side. The onky issue doing this i can see is its easier to lift one or two legs on the steel stand then lifting a corner of the wooden stand because that stand is one peice so lifting a corner of the wooden stand creates a gap on the length of the wood on the bottom. But this happens even on a hard surface concrete surface.. If one end is lower and you jack that end up itll bring up the wood veam on the entire bottom with it

The steel stand was no diff for example i had to shim the front right legg up with 2 steel shims the rear right no shims. The front left leg i had to shim up with 4 steel shims. And the rear left i had to shim with 3 shims.

Im noticing this on the wooden stand.. No shims in the rear right left. 1 shim in the front right . And 3 shims in the left front progressivly going down to 2 shims towards to back left. The entire front i shimmed with 1 shim to keep the wood level and tilt the tank back as it was leaning slightly foward. The floor has always been uneven like this since day 1 with the steel stand.

And the shim placement is identical on the steel stand with the wooden stand. Am i making sense here ?

I thought about keeping the steel stand up there.. Its just so damn ugly and weighs probly 150 lbs more then the wooden stand.

Are you trying to tell me a steel stand shouldnt flex ? Like if the floor were conrete and level on all but say the front left leg.. with the fish tank on it filled are you trying to say that front left leg should have a gap in it and the floor not bending down at all in that corner.. Even with steel i dont see how anything can be that rigid.. If thats the case i sure didnt see that on my steel stand i had to jack each leg differently to get the 4 corners of the tank to be level with eachother.


The onky thing i did notice with the wooden stand is the left and right corners with a level were a hair higher and as you go to the middle its level. Almost like its bending in a U shape.. not alot its all within level but it was noticable even the water level seemed a very hair higher in the center then the corners. The steel stand i never noticed that i dont think.

Another thing that has me wondering.. is this tank is 40 years old.. snd its been on that steel stand for 40 years.. I kinds wondered if its best to stay on the stand its been on for 40 years due to how the fish tank might be accustomed to that stand..

God damnit man... Its so much work lifting that heavy *** steel stand out of storage into my truck up 3 flights of stairs.. drsining the tsnk taking the sand out so make it lighter and moving everything.

It was just sooo ugly.. you see how ugly that open stand is showing all the wires pumps.. and those 2x10 boards i had it on to help spread the weight on the subfloor better.



Here isa pic of the steel stand



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