Need help leveling 90 gallon!!! Gap under tank??

[Kallen]

The last few years has been rough with my hobby. Few years ago, I had a seal go bad. I have hardwood floors, and it was raining in my basement. So I removed the old seals and resealed the tank. Lasted 2 years, busted again. Gushed a lot worse. So I decided to get a new tank (this is about 5 months ago). After the new tank was up for about 2 months, I realized it was not sitting flush on the cabinet. I could take a piece of paper and freely slide it between the bottom of the tank and the cabinet. Only three corners were supporting the entire 90 gallon tank. So I drained off about half the water to reduce the stress on the glass until I could get a new cabinet.

Let me mention that my floor is not level, and the old cabinet had shims under one side. A level on top of the tank showed it was a little off, but not a LOT... I also realized that the floor of the cabinet (particle board) was severly warped. So I assumed the cabinet was at fault.

A few days ago I picked up a new cabinet. So tonight I started setting it up. The level on top had just the tiniest bit of the bubble outside the line, so I figured I was good to go, no shims. As I started to fill the tank, I kept an eye on the water level on both ends. I am a little under half full, and I realized I am way off from level again. Side-to-side is about 7/16 (.43) inch off. And front-to-back I am off a little over 1/8 inch. I took a piece of paper, and I can once again freely slide it between the tank and cabinet in the middle (side-to-side) but the sides and corners are firmly touching.

So, the new cabinet is definitely supporting the weight better than my original cabinet. But I am concerns about the almost half inch difference and the gap under the tank. So I need to know:

1) Is a gap big enough to allow paper to slide under normal or of concern???
2) Do i need to be concerned about the almost half inch or should I just go with it and not worry???

Thanks!

 

[exhumed07]

i would try to shim the cabinet if possible to level it out. i don't think it's much to worry about but i'm kinda a perfectionist. and the gap i doubt would be much of a concern as well. i checked my tanks and they do the same thing. my 55 i can but about 4 sheets of paper stacked and it's been there for about 6 years now. wish i had better advice but thats all i can give

 

[Kallen]

i would try to shim the cabinet if possible to level it out. i don't think it's much to worry about but i'm kinda a perfectionist. and the gap i doubt would be much of a concern as well. i checked my tanks and they do the same thing. my 55 i can but about 4 sheets of paper stacked and it's been there for about 6 years now. wish i had better advice but thats all i can give

I KNOW the 3-corner was a problem with the old stand, but I feel better that yours has the middle like that too. Thank you for checking that out!

As for shimming one side, you don't think that would put too much stress on the cabinet and cause it to warp? That's what I am afraid happened to the first one.

 

[Kallen]

Update:

So I put 1/2" shims under one side, almost the entire length of the side. On the old stand I just had the corners shimmed. So this time around, I used long shims and the entire side is resting on it. I figured this would be better and might help. Filled with water and its dead level. (Tank is leveler than it has ever been).
The only concern this created was the setup now easily rocks front-to-back because of being shimmed so high. So I took a couple scrap pieces of thin wood and slid under the middle of the cabinet (in the front and the back both) and this seems to have stabilized it greatly. I can still rock it a little but not enough to worry me of tipping. Also, once the 720 lbs of water was added and the shims added, the middle of the tank now touched the middle of the cabinet. I am still concerned about being shimmed so high...

 

[skjl47]

Hello; Sounds like you have a gap between the tank bottom and the stand?? This may not be an issue depending on how the manufacturer of the tank wants the tank to be supported. Perhaps a check with them will yield some information.
I have set up many tanks over time and have not shimmed between a tank and stand. I use shims between the stand and the floor. Perhaps the first thing to check is the actual level of the floor in the area under the tank. A 90 gallon tank is heavy enough to possibly cause some floor deflection as well.

I check a stand for level without the tank on it using the longest carpenter’s level available. I place shims under the stand. I use solid shims and in latter decades have used metal shims.
If the stand checks level I then place the empty tank on the stand and check for level again. If still true I fill the tank slowly and re check the level from time to time.
In the case of a gap between a tank and the stand I have been using 1/2 inch to 3/4 inch sheets of plywood between the tank bottom and the stand. The plywood will flex a bit and close the small gaps, with the 1/2 inch being the more flexible. You still want to wind up with the tank top level from side to side and front to back.

A straight edge/ long level across the top of the stand should help check for being warped or out of true. If the stand is out of true a lot, this issue should likely be addressed in some manner.

Please note that most of my experience has been with numerous metal stands. I used a wooden stand under a 55 gallon for the first time three years ago so am somewhat limited in experience on shimming this type. I do not know from experience how well wooden stands react to narrow width shims in small areas. It may be that shims for such stands will need to be much wider to be effective over time. Metal stands take a set with weight right away that does not change over time. I can picture wood perhaps moving under the weight and dampness over time.

I think that you are correct in being concerned about an out of level tank. Start with the structure of the floor and work your way up. One of the things about this hobby for me has been figuring out such issues.
Good luck

 

[exhumed07]

I have one home made stand for a 30 gallon made out of 2X4 and plywood. one other 30 gallon is on an antique cherry desk. it needs to be restained and sanded so i'm not to worried about water getting on it at the moment lol. and then my 20 gallon is on a open top store boght stand, the stand only supported 2 ends of the tank and i cut a piece of 1/8 inch plywood on it to keep it unnoticable. and my 55 gallon is sitting on an old 1970s console stereo. the 55 been on there for over 5 years now. but everything is 100% level. but i have noticed gaps between the tank and stands. and kinda thinking about what skj said it reminds me of a flatbed trailer. they are made with a possitive arch to flex to level once weight is added. it may be possible that the tank could be made in the same way. glass is flexable and technically a liquid so a bit of flex is normal and expected. it realy has me thinking now lol