structural engineer needed?

[thefuz]

Hi folks,

I'm bringing the 90 gallon oceanic into my living room this weekend and I'm getting a little nervous about the floor support for all that weight. Unfortunately, the spot it's going will put it parallel with the joists. There's a double joist supporting the wall behind it, but only single 2x9's spaced at 14" across the rest of the living room.

Anyone know of a local contractor or structural engineer that I might be able to consult? I have some friends in the business, but I don't think they're fully versed in this particular subject (live weight vs. dead weight, etc.). I'm not concerned about the floor giving way completely... just sag. I can only imagine the disaster from 90+ gallons if the tank seems were to give.

Oh, also - have any of you added a tank to an insurance policy?

 

[MrMatthew]

If the joists are exposed in the basement it would be a peice of cake to sister the joists that will be under the tank. Thats probably the only solution you'll be able to do. That will deffintily stop any sagging from weight.

 

[thefuz]

Unfortunately, that area of the basement is finished. Sistering will require ripping out at least a portion of the finished basement ceiling. The tank area is in the corner of the room closest to the exterior of the house. Given that it will be centered on the short length of wall separating the LR from the front hallway, it will be about 2 feet from the exterior edge. Wonder if that helps.

 

[JoeBellz]

Is there any way you can put the tank in an area where it will sit perpendicular to the joists? Maybe forego pleasing aesthetics vs piece of mind. The constant 24/7 weight of a 90g (+ sump if you were using one) would definitely worry me if it was running parallel to the joists. Is the house older or newer?

I debated going 93g on my 2nd floor with joists running perpendicular against a load-bearing wall, but opted to go with a 70g and I have a sump too. I do check the level of the tank every so often to make sure there is no bowing in the floor.

It's so hard to really debate if it would be safe or not over x amount of time, so many variables are involved. Some will probably say it will be fine, others will say don't chance it.

Best of luck finding a structural pro to give you some sound advice.

 

[thefuz]

House built in 1950 and there will definitely be a sump. There's one other spot in the dining room. But that too is parallel (of course!). Anywhere else is either already occupied or not feasible due to space with other things. I've talked to several contractor friends and some folks from various LFS (Greenwich Aquaria, Wesport, etc.) and they say I should be OK. It's going to be about 2 feet from an exterior wall, so that will be helpful on one side at least. I just need to keep an eye on the level. If it gets bad, i'll move it to the basement. The stand is about 20", so I'm hoping I'll be able to cross two joists.

 

[ctreefer]

I wouldn't be too concerned. It sounds like you have 2x10's? actual dimension of a 2x10 is 1.5 x 9.25.

I had a 90 setup similarly (parallel to joists) for a couple years with a sump and had no problems. (my joists were only 2 x 8's) and the tank was also about 2 ft from the exterior wall. House was constructed in the 50's as well and had diagonal tongue and groove subfloor with hardwood flooring on top.

 

[JoeBellz]

House built in 1950 and there will definitely be a sump. There's one other spot in the dining room. But that too is parallel (of course!). Anywhere else is either already occupied or not feasible due to space with other things. I've talked to several contractor friends and some folks from various LFS (Greenwich Aquaria, Wesport, etc.) and they say I should be OK. It's going to be about 2 feet from an exterior wall, so that will be helpful on one side at least. I just need to keep an eye on the level. If it gets bad, i'll move it to the basement. The stand is about 20", so I'm hoping I'll be able to cross two joists.

older house is def a +, sounds like you will keep an eye on it so should be ok. AGain there's so many different variables it's just something you'll have to go through to see if it will work.

 

[thefuz]

I wouldn't be too concerned. It sounds like you have 2x10's? actual dimension of a 2x10 is 1.5 x 9.25.

I had a 90 setup similarly (parallel to joists) for a couple years with a sump and had no problems. (my joists were only 2 x 8's) and the tank was also about 2 ft from the exterior wall. House was constructed in the 50's as well and had diagonal tongue and groove subfloor with hardwood flooring on top.

Yup, that's the joists we have as well as the hardwood/subfloor. I'm going to fill it partially a couple of steps at a time and see how it settles in between. Thx for the support tho - I'm just looking for piece of mind. I don't know what's a worse disaster; 100 gallons on the floor or all the lost critters. My wife and I will differ on the answer, I'm sure!

 

[scolley]

There's another factor here that no ones brought up... the confidence of manufacturers of not being sued. There's a reason why commercial tanks typically top out at 180-220 (same footprint). It's the same reason why most tanks don't ship with all kinds of warnings about floors and such.

Have you ever looked at all the warning labels on a ladder? Oh my gosh! But not on tanks. Why?

Because manufacturers have figured out that throughout the USA pretty much universal building codes (or universal minimums) protect them for suit - because the floors hold - as long as they don't make the tank TOO big. That's why the line is almost universally drawn at the 180-220 footprint.

So IMO, if your house was built to code, you shouldn't have to worry about the tank. However, that sump might be a different story. What's the footprint of your 90? And is there another - commercially common - size tank that has the same footprint, but is larger. So without looking it up, let's assume a 110g has the same footprint. If so, then you can conclude that manufacturers are comfortable with 110g of water weight (in a building built to code) spread on your 90gs footprint. So a logical conclusion is that you can have the difference in capacity (110g - 90g = 20 gallons) as the size of your sump at no risk. Or am I off base because a 90g has the footprint of a 75g? Hmmm... need to go look that up.

Either way, you should be good for your tank. It's your sump you gotta worry about.

It's another way of looking at the issue. Hope that helps.

 

[thefuz]

Thanks. That's good reasoning, scolly. I've been thinking along similar lines; especially after more conversations with a few contractor friends. I don't have exact dimensions on the sump (tank is not in hand yet - but Sunday!!). Based on what I recall from seeing it, I'm guessing it will probably hold around 20 gallons at any given time. It's set up as a wet/dry now, so it's less than that in the current setup. Wet/dry go bye bye when reef comes to town tho!

 

[scolley]

OK... I had to noodle on this a bit more. 'Cuz my "some tanks can take a sump in the same footprint because other larger tanks have the same footprint" argument does not apply to you. You're 90s got the same foot print as a 75. So people with 75s can put in a 15g sump with no worries, because 90s are OK. But there's no such assurances for you.

So I looked up tank sizes and weights here. That source does not specify whether the weights are for freshwater (probably) or salt. But it really does not matter. Keeping in mind that manufacturers plan on not getting sued, the link's weights may be a shade low (freshwater) but the logic below still applies, 'cuz tanks don't ship with at "No guarantees if you fill with Salt Water" labels. So...

In the above table I took the data from the tank size-weight website, and calculated the pounds per square inch and pounds per linear foot for each sized tank. The bad news is that you are on the high size. The good news is that you are still under not the highest on either metric.

Then off to the right I figured the total weight of your tank (yes, freshwater) to find those same two metrics with a 20g sump. And what does that tell us?

Well, you are over the top on Lbs PSI, even more than a 150. However it's only fractionally more. If that small overage mattered, tank manufacturers of 90gs would put a sticker on them that says "No guarantees if you put a light on top of this tank." But they don't. So people that make tanks feel like your pounds per square inch is OK in homes built to standard codes, maybe even with some stuff put on top of them. :thumbsup:

And as for the lbs per linear foot, you're way under a 180 (which IS way wider), but also just a shade above 150's. So same logic above applies.

So what would I conclude? You're ok with a 20g sump. Do not store bricks in your stand. And if you do some floor weight reduction measures like suspending your lights rather than having a hood, you are golden.

Hope that helps. Drop by a club meeting some time (this month at Joes?) so you can know who to punch when your tank drops thru the floor one night. LOL

 

[thefuz]

LOL thanks for the added info - your reasoning certainly makes sense. Filling it slowly and seeing what happens is my first step. It will take me a little while to make all that RO water anyway!

Definitely looking forward to meeting you folks later on this month!

 

[scolley]

Good luck!

FWIW, I had a 75g blow a seam in the middle of our family room one afternoon. The wife came in, saw me with buckets everywhere, more wet towels than you want to imagine, Persian rug soaking wet on top of the couch, and water EVERYWHERE. She took one look, and in a eerily calm and quite voice said,

"You're buying me new furniture."
​

Then turned and walked away. Wow! Fortunately I had the good sense to realize when discussion was over, and kept mopping, all while trying to figure out just how much that might cost.


I share that story just to say... it happens. Be ready to keep a cool head if it does.


Good luck! See you soon!

 

[dakineacct]

Well, you are over the top on Lbs PSI, even more than a 150. However it's only fractionally more. If that small overage mattered, tank manufacturers of 90gs would put a sticker on them that says "No guarantees if you put a light on top of this tank." But they don't. So people that make tanks feel like your pounds per square inch is OK in homes built to standard codes, maybe even with some stuff put on top of them. :thumbsup:

And as for the lbs per linear foot, you're way under a 180 (which IS way wider), but also just a shade above 150's. So same logic above applies.

Lbs per linear ft is really irellevant, you cant compare a 90 gallon to a 180 using plf because they are not the same width. Depending on position of the tank, it is possible that the 90 gallon could bear on only one joist. The 180 gallon will always bear on 2 joists. (However, in the real world hardwood floors and a subfloors will permit some load transfer to multiple joists in either siutation).

From the table that Scolley made, the 90 gallon with a 20 gallon sump is the highest per square inch, which is what matters. The other factor, that has not been mentioned is the joist span legnth. The longer the span between the joist supports, the smaller the load required to cause bending or sag. Just something else to consider.

 

[thefuz]

Not sure if it's helpful, but this is a photo of the spot the tank will be occupying in a few hours. The joist runs about 15 ft length under this area, spaced at 14". There is a pair of joists sistered directly beneath the wall there.

 

[thefuz]

Update - got it in - phew!! Some of you may have moved large tanks before, and now I feel your pain! Anyway, placement of the tank attached.

On a side note - he gave me this wet/dry and I'd like to figure out if I can convert it to a sump (it's 30"x16" and 18" high on the trickle side). I'm thinking of having the overflow drain into the right chamber and host a fuge there. As an alternative - maybe have an algae filter on that side instead. I'm still on the fence about them though.

I do have a skimmer - Euro Reef 135. If I have that on the left side along with the return pump, will that be a problem?

Geez - this is turning into a build thread now. Perhaps I'll start something official on that front later.

 

[scolley]

Cool! Do you need a level? A good one? As you slowly fill things, that's gonna be your best indicator of a problem in progress.

Lemme know if you need to borrow one. I've got several.

Build away!

 

[thefuz]

Nah - i have several, including an old school steel one from my Dad. But thanks!! Already practiced shimming into level position empty and it was all good. Now I have to move it again b/c I neglected to paint the back before moving it into the living room - too excited.

Speaking of painting the back - rustoleum oil flat black OK? I'll see how 2 coats does. Thinking I should have just done latex so I won't have to deal with thinner to keep the roller wet or clean between coats - but oh well.

 

[thefuz]

OK, wanted to update this as I've gotten the tank set up and thought it was level... but either I did a crappy job or the tank has settled. Either way, it's off about 3/16" end to end (round it up, 1/4"). Anyone with experience on this? Think I should drain it and level again or will it be OK to leave it? The level difference is only apparent when the return pump is off... otherwise you can't see it at all unless you look into the top of the tank (and even then it's hard to tell). Overflow is unaffected. Is this just an aesthetic issue or should I be concerned about stability of the seals?

 

[terahz]

I would remove the water (but save it), shim the stand and put the water again until it is as level as you can get it. Take the time now to do it right.