Is this safe? Uneven support

[ReefSlice]

Thanks for the compliments. I can see no way that it would be the stand at this point. I completely trust it and tested that it was perfectly square and coplanar before placing the tank on it. I didn't test the tank yet however so not saying for sure it's the tank until I get a better look. However, take a look at these pictures to get a better picture of what I'm dealing with here. Sorry it's hard to focus the camera holding two things, but you can clearly see the gap between stand top and tank has quite a difference even with the foam. The back corner here is basically squashed down, and the tanks half empty.
Front

Back

@Reef Dude I really appreciate the replies, it is definitely calming to know I'm not the only one, however I wish Steve would handle it better, as this could potentially be a large hazard in our homes, and you know he isn't replacing the floors and drywall if they come down...

 

[Caravanshaka]

The tank is built with the front and side panes going all the way down to the bottom of the center pane. The difference this makes, is that the very corners you are looking at are not taking downward pressure, but outward pressure. You cannot see how level the bottom pane is with it on the stand like that, but that is the pane taking all the downward pressure and the one that needs to be supported evenly.

Take a look at Waterbox and Red Sea tanks....the front pane of glass is floating in air on them because they build their tanks in this style.

If you are 100% sure your stand was level, what I would do is take your level and lay it across the bottom pane inside the tank. If you can't find any part of that bottom pane that is out of level, I'd fill it and never think twice about it. If you see any piece of that pane is unlevel, then I would go through the effort of flipping the tank and getting a really good look at how the side panels measure up with the bottom panel to determine if it is just the side panels being slightly off or if it is truly the bottom panel that supports the downward pressure.

As a side note, I have a custom SCA tank and my side panes were not 100% perfectly square, so I've been through this. What is important is my bottom pane is perfectly flat. been filled almost a year now with no issues. I am also using an 80/20 stand.

 

[ReefSlice]

I came up with those exact conclusions, and I am totally fine with just part of the front pane hanging up. My problem is I can't tell how far in the gap goes until I have it drained with no sand in it.
I just measured from the bottom of the stand (excluding the leveling feet) to the top of the plywood and then again from the bottom of the stand to the top rim of the tank on all four corners. As I predicted, height to top of plywood on all four corners is perfectly 38 3/4" (exactly what I asked for). However from the bottom of the stand to the rim of the tank, there is an 1/8" discrepancy between the front right and front left corners, as well as the same on the back left and back right corners, ranging from 1/16 under 62 3/4 on the low corners and a 1/16 over 62 3/4" on the uncompressed corners (back left corner 1/8" higher than back right, front right corner 1/8" higher than front left corner). So I strongly believe it's either two misaligned panes (front and back) or the whole base is warped. Both pretty much unacceptable to be honest for a custom tank. Will keep updates coming as I learn more.

 

[PicassoDan]

Someone mentioned this already, but this has nothing to do with the tank or the stand being level.
It has everything to do with FLATNESS.
When you have gaps at opposite corners like that, you either have a stand that is not flat or a tank bottom that is not flat, or more likely both to some degree. No amount of leveling is going to help.

I would personally do the following:
Empty the tank and flip it upside down.
Take the foam off the stand and check the plywood for flatness. Not levelness. Flatness. Check with a good straightedge (a level will work). Check at each edge of the plywood, the center in each direction, and diagonally from corner to corner. Use a small shim to check for space under the straightedge as you go.
Repeat this process for the bottom surface of the tank.

 

[dansreef]

Beautiful tank and a vexing problem! If it is something that concerns you I would work backward and do it over.

The one piece that strikes me in what I have read is the mat you used was a yoga mat, correct? As someone else said, the quality of the foam and the inconsistency of the density could be the reason why you are seeing the difference in thickness. I think this would be something that both explains what you are experiencing, but also could be a bigger concern with your system. If the density consistency is a problem, where are there other differences under your tank you cannot see? Could those inconsistencies see additional stresses over time which could lead to failure?

I think I would be inclined to replace the yoga mat with foam board as others use. It is denser which would make the inconsistency less of an issue.

I look forward to seeing your tank come together.

Good Luck!

 

[ReefSlice]

Someone mentioned this already, but this has nothing to do with the tank or the stand being level.
It has everything to do with FLATNESS.
When you have gaps at opposite corners like that, you either have a stand that is not flat or a tank bottom that is not flat, or more likely both to some degree. No amount of leveling is going to help.

I would personally do the following:
Empty the tank and flip it upside down.
Take the foam off the stand and check the plywood for flatness. Not levelness. Flatness. Check with a good straightedge (a level will work). Check at each edge of the plywood, the center in each direction, and diagonally from corner to corner. Use a small shim to check for space under the straightedge as you go.
Repeat this process for the bottom surface of the tank.

Yes, duly noted, that is what I was trying to clear up as everywhere I look gives conflicting answers, but I always figured the level had nothing to do with it... 2 flat surfaces always match up regardless of level, I've tried telling some people this and they look at me like I have 3 heads. Glad I got it cleared up, I thought I was going crazy!
And I did just that with the surface of the stand. So I'm very confident that the stand is just fine. It's a very well thought out design.

 

[ReefSlice]

Beautiful tank and a vexing problem! If it is something that concerns you I would work backward and do it over.

The one piece that strikes me in what I have read is the mat you used was a yoga mat, correct? As someone else said, the quality of the foam and the inconsistency of the density could be the reason why you are seeing the difference in thickness. I think this would be something that both explains what you are experiencing, but also could be a bigger concern with your system. If the density consistency is a problem, where are there other differences under your tank you cannot see? Could those inconsistencies see additional stresses over time which could lead to failure?

I think I would be inclined to replace the yoga mat with foam board as others use. It is denser which would make the inconsistency less of an issue.

I look forward to seeing your tank come together.

Good Luck!

Thanks for the input but the yoga mat has nothing to do with it sadly, if it was inconsistent thickness the tank would still be resting at the same height on all four corners, which it is not.
I hope for everyone's sake I'm wrong... But it's very possible there's many others with the same problem here that haven't even noticed because the foam does kind of cover up the problem. Only reason I really noticed is because when I had this tank on a stand with thinner foam, the gap was a lot more noticeable.

 

[PicassoDan]

Yes, duly noted, that is what I was trying to clear up as everywhere I look gives conflicting answers, but I always figured the level had nothing to do with it... 2 flat surfaces always match up regardless of level, I've tried telling some people this and they look at me like I have 3 heads. Glad I got it cleared up, I thought I was going crazy!
And I did just that with the surface of the stand. So I'm very confident that the stand is just fine. It's a very well thought out design.

Yes, you're on the right track : )
Actually, as long as the two surfaces have the same shape, they don't even have to be flat, but I digress...
Do you have the tank upside down yet?
Optional --> When you flip it over, set the tank on three pads (maybe 6" diameter or so), one under each back corner and one under the center of the front edge. This will minimize the tank warping under its own weight and give you a better measurement.
Also, before putting the tank back on the stand, make sure each of the leveling feet is on the ground and has approx. the same load on it. I worry about open stands like that with no shear panels warping once weight is applied.

And I absolutely don't think you're being crazy about this - I had a 120 crack right down the center because the stand that it was on was not flat.

 

[Eagle_Steve]

In my profession, I design things to within 10,000ths of an inch. The only true way to determine if this is going to be an issue is to check the bottom pane of glass. The way this tank is built places all downward pressure on the bottom pane of glass. Yes, with the side panes not being exactly square with the bottom pane, it looks funny and reduces the actual contact area of the side/front panes to the bottom pane. This contact area is very small and applies to the surface area for adhesion of the silicone mating the two pieces together. Again, minimal and negligible as to if it will actually be an issue with the outward pressure and the side/front/back panes holding the adhesion.

Below are the steps I would take if it concerned me.

1. Drain all water from tank and remove all items in tank.
2. Flip the tank over and check the actual flatness of the bottom pane.
a. quality straight edge laid across the glass in numerous directions (front to back in multiple places, diagonally from corner to corner, etc.)
b. use a feeler gauge in hundredths of an inch (like used to adjust valves on a car) and try to slide multiple thicknesses under the straight edge.
c. if a (edit) feeler gauge is not available, a sheet of paper will work..
3. Note all of the measurements with the feeler gauges. Compare those measurements to numerous listing online for glass flatness allowances.
4. If they fall into those variances, roll with it. If not contact the manufacturer, provide them with photos of a straight edge laid out with the feeler gauge underneath it and show them how far it is off.

On a side note. I do have an SCA tank and it has some variances like you are experiencing. I also have RedSea tank, a JBJ45, as well as a few other rimmed tanks. All of the rimless tanks have slight variance for where all the panes meet the bottom. What matters is do they fit into an acceptable level of variance. All items man made will not be perfect. Even glass floated on a truly laser leveled vat of molten tin will have a slight variance.

In closing, check this as this is where you would have to worry about downward pressure creating flex to cause separation, flex, or cracking.

 

[PicassoDan]

As far as flatness tolerance, I would base it on the compression of the foam. What is the uncompressed foam thickness? If the foam easily compresses from say 1/4" to 1/8", then I would think about ~20% of the compression would be OK. So make sure it's flat to better than ~ .025"

 

[ReefSlice]

Unfortunately I'm going to need to recruit a few guys to come over and help me to take it all apart and flip it, that alone will take a few days, and even then I'm not entirely sure how to safely flip a 350 lb tank over onto it's top... Any suggestions here? That sounds nearly impossible to me without damaging someone or something!
Not entirely sure how I will continue here, because just getting the muscle to achieve that is going to be very tough. I guess I will just be draining it for a while until I can figure out how to do this and get some help.
The mat thickness is 1/4", and on the compressed corners it compresses down to nearly 1/16" at the lowest spot (back right), while the corners that don't compress are just barely touching the mat without really compressing anything at all, especially the front right. I can slip a credit card between the mat and tank on the two high corners, but it's a very tight fit on the front left, and then the back left it is impossible to get anything under the corner, it's basically smashed down all the way to the plywood.

 

[Aquavaj]

I have a SCA 120 that is doing the opposite. The front corners are more compressed than the center. I didn't even noticed this until a few weeks later. When I looked closer the top of the stand was bowing ever so slightly. You won't notice looking straight on but you can tell looking at an angle. I don't know how far the gap goes underneath the tank cause I never bothered to test with a piece of paper. Tank has been up since Sept and it's still early but no issues so far even with a canopy sitting directly on tank.

 

[Todd Jacobs]

When u leveled the tank it was obviously empty but as ur filling it u should keep checking the levelness every few gallons and finally at the end full As it looks in pic its level and full i would say i bet its the mat maybe something a little thicker then the yoga matt would have been better if its level and there is no shake u should be good also put the level on the side glass maybe its the tank one more thing did u chk the level of the stand first with no tank then with the tank just trying to chk every option im sure its fine

 

[PicassoDan]

So, I think if you get it emptied, you could check flatness (not level) of the bottom pane of glass from inside the tank. So, no need to flip it!

 

[vetteguy53081]

No. tank must be totally level as you will shift forward weight, weakens seals and likely in time produce a possible leak from weak seals.

 

[PicassoDan]

If you read the thread, the OP reported that the tank and stand we're both very level, and yet there was still this issue with gaps under two opposite corners. Nobody is saying that the tank shouldn't be level, just that that isn't the issue at hand.

 

[ReefSlice]

I will try to check the bottom pane from inside the tank and check for gaps with the tank empty again, should give me a better gauge without any deflection. If I think it's necessary I'll move the tank to a flat surface with no foam to get a better illustration of the gap and take some measurements with a feeler gauge or paper that way.
I've got a busy weekend ahead, so today I'll finish draining the sump and tank and then it'll have to sit dry for a few days before I can really get to the bottom of it.
I need a few days away from this anyway, it's been making me absolutely crazy!

 

[jon99]

I definitely don't want to hear something terrible... But if something terrible needs to be said, I'd rather hear about it now instead of when there's 150 gallons of water on my floor.
Basically what I'm looking for in this post is anyone with tanks that have been running for years that have the same issue. Because in my eyes, it looks like some obvious point pressure on the 2 corners that are bearing weight... Call me crazy, but just imagine 150 gallons spilling in a second story condo! If that is even a possibility then it needs to be corrected now versus later.

I have a 210g Aqueon that had a similar issue. When I placed it directly on the stand (which was topped with a piece of granite countertop, which was perfectly
flat) it rocked from corner to corner
diagonally. I would say there was a good 1/8” gap. I ended up putting styrofoam between the granite and aquarium to make up for some of this difference and 9 years later it’s still going strong.

My aquarium is built a little different than yours. It’s on a plastic frame, so the bottom pane is floating and does not come in contact with the stand. The bottom pane is also tempered which allows it to float and support all the weight of the water and the rock above without having to be supper thick... but for what it’s worth, not being supported 100% equally on all corners did not effect its performance ime.

 

[ReefSlice]

I have a 210g Aqueon that had a similar issue. When I placed it directly on the stand (which was topped with a piece of granite countertop, which was perfectly
flat) it rocked from corner to corner
diagonally. I would say there was a good 1/8” gap. I ended up putting styrofoam between the granite and aquarium to make up for some of this difference and 9 years later it’s still going strong.

My aquarium is built a little different than yours. It’s on a plastic frame, so the bottom pane is floating and does not come in contact with the stand. The bottom pane is also tempered which allows it to float and support all the weight of the water and the rock above without having to be supper thick... but for what it’s worth, not being supported 100% equally on all corners did not effect its performance ime.

Good to know. Just no good scientific way to calculate if it's safe or not, it's frustrating.
Got the tank and sump 90% drained, corners still look pretty similar. I can slip a piece of paper under all the corners if I work it back and forth, but it's definitely tighter on the back right and front left corners. The paper does get stuck a few inches in on all corners so I guess that's a plus. Will post some more pictures later after I get a hold of some feeler gauges.

 

[ReefSlice]

Well... Here's what it looks like with the tank pretty much empty other than rock and sand, so still compressing a bit, and you can see the corner is not making contact at all with the mat, and it seems like it goes in even further, which really sucks.

I also emptied my sump and still cannot slide paper or anything under the rim of the tank anywhere. So this has nothing to do with the stand, it's perfect.
Here's a picture of the other front corner to show how I would imagine it should look. Seems this corner and the back right are certainly lower, causing the tank to sit on those two and not allow the other corners to sit down. That seems like a very bad pressure point if the whole tanks basically propped up by 2 corners.