[flytekk]

Hi im new here. Built a aquarium stand this past weekend but i think i made some mistakes.

I used pressure treated wood. 4x4 from homedepot. Some people tell me that this wood will warp and crack due to chemical moisture in it. Is this true? I would hate to put my 2000lbs aquarium on it and tthat would happen. Here's how it looks.

Anyone please help.

 

[BernieL]

Flytetekk - Welcome to the best forum on the net because of the folks who post here. I haven't checked the "intro" thread so if you haven't introduced yourself yet, please do.

Now to your question... yes pt (pressure treated wood) will check which is a process of any and all woods drying. Simply explained, this means that all wet woods need to acclimate to their environment and most often this means to drier conditions. The checking will produce cracks in you pt wood but simply stated, the checking will probably (97% sure) not effect the integrity of your structure. Your structure will hold a lot of weight. Put your tank on it and have a good night sleep!

What the checking will do is effect the looks of your stand... especially the ends of the 4X4's.

In the event that you decide to become a serious woodworker, you will need to relax and learn to live with lots of mistakes. Serious woodworkers still make mistakes... the difference is that we craftsmen know how to hide our mistakes.

 

[flytekk]

THANK YOU!!!! Im getting alot of grief over on the reef forums. Here's what they are telling me.....

There is nothing holding these joints together other than screws.
I would not trust this as a relatively little amount of side load would knock the whole thing over.
You need to lap joint and through bolt the middle supports to provide lateral support and tendon and through bolt the corners to provide complete support. This looks like a huge puddle on the floor waiting to happen.

using pressure treated wood is very risky, as it dries out it tends to warp, also using 4x4 isnt a real good choice, i would not use that stand! as barrie said, huge puddle on the floor waiting to happen.

The pressure treated wood as it dries will warp, could crack your tank, I would not put a tank on that, jmo

If this was regular 4x4 material I would say you could cut out some of the wood in the corners to reinforce the joints with additional pieces. But this pressure treated wood will not age well since the moist content is high. As some of the chemicals in the wood dry further it will not stay consistent. This is how wood warps.
The pressure and forces inside a 4x4 could easily create high and low spots over a 6 foot piece that will weaken the integrity of the tank over time. You want this stand to be as flat as possible and this will work against that.

I am also not convinced of this stands lateral strength.

I also agree pressure treated wood warps quite a bit.

 

[Bastien]

Those sound like legitimate concerns. I think the 4X4s are strong enough, but you mentioned nothing of your design. Four vertical sticks, regardless of their strength, can be knocked over with enough lateral force without precautions in their assembly. The part about keeping the tank's supporting points flat is interesting. It sounds like that response was well thought out. Honestly, it sounds like you're seeking affirmation rather than genuine help. If they were nice about it, would that have helped you accept their opinion?

 

[J Thomas]

Welcome aboard fly.. Good to have ya!
Lateral pressure as in someone bumping into the stand could be an issue. Could you add some 45 degree braces similar to these?

Sorry about the huge pic.. just something I grabbed from the net.
..Jon..

 

[cabinetman]

First, what are your plans for the exterior. I'm just guessing that your finished stand will have some further treatment. Depending on what that may be may help to minimize what your structural additions may be.

.

 

[Dave Paine]

The reef forum folks are correct to be concerned.

PT lumber is very wet. I have purchased pieces which had beads of water on the surface.

It is the water which is the future issue not the chemicals.

As the water dries out the wood is going to crack and warp. I do not recall using a PT 4x which did not warp to some extent later on.

I would be most concerned about warping of the top and bottom pieces.

If the top pieces warp you will not have consistent contact with the bottom of the tank which could lead to undesirable stresses on the tank.

If the bottom pieces warp then the vertical members will not equally share the load and could add to instability.

The structure should really have decent joints not just the metal L brackets. If the wood warps it will pull out the screws.

FYI, if you rebuild with construction lumber, even if it states "KD" which means Kiln Dried, it still it likely to have more moisture in the wood than your shop or home.

The wood should be allowed to acclimate to your shop/home moisture content. 4x members will take longer than 2x members. At least a month.

If you let the wood acclimate, and it warps, you can attempt to clean this up being assembly.

 

[amckenzie4]

People more knowledgeable than I have already replied, but I'll put in my penny's worth anyway.

This stand may be fine, or it may not: the only way to know is to wait. Here's what I recommend. You've already invested the time and money into building it, so don't just throw that away. Find a safe place (ideally somewhere the same temperature and humidity as the room where it will finally go) and set this aside for a couple weeks. In my experience, two weeks in a dry environment is enough to tell you which boards are liable to warp. In this case, it may be all of them, it may be none of them, or, most likely, it may be some of them. I've seen pressure treated lumber bow and twist, so I'd be a little concerned about just setting up the tank. A twist in the verticals will be a cosmetic issue, but not much more than that. A twist in the long horizontal members could be catastrophic if there's a tank sitting on top of them.

If you were going to re-build, given the weight, I would go for either dry solid wood (construction lumber, set out to dry long enough that you know it's warped as much as it's going to) or a metal frame, preferably professionally welded. Water weighs a LOT, as you know, and the stand really needs to be solid. The design you have is good vertically: if you were to screw a plywood face to the back and sides (1/4" would probably be fine) I'd stop worrying about horizontal strength as well. I did that to an old workbench, and it made an enormous difference.

 

[Turbosaurus]

Im a multiple tank keeper, and I have brand name pre-made stands for my tanks. My 125 (6'x 18" I think) is on a commercial stand, you would not believe what holds this tank up. There are 5 pcs of 1x3 in front and back with 1x supports between them. That's what the entire tank rests on... those ten little tiny 0.75"x2.5" points of contact. I cant tell how they are joined to the 1x braces that keep them square, but I didn't spend enough on this for fancy dovetails - I bet they're just routed for the overlap and glued (shudder). You overbuilt the crap outta this thing. FYI- I also have two very large and rambunctious pitbulls who slam each other into the stand on a regular basis as they recklessly and thoroughly chase each other through the house- and I cringe every time- but they're 13 now and the tank and stand have made it fine so far... Knock wood. I have smaller tanks on pressboard stands help together with a handful of screws and some cam bolts.- Im always shocked.


I would be concerned not about the strength of the stand, this baby's not going anywhere- Warping potentially causing uneven pressure on the glass and eventually weakening the seams- maybe. I don't know enough about engineering and stress direction sheering etc. Does the tank have a plastic frame? that gives you a LOT more leeway... If its frameless, you might have an issue. A lot of people will put pads in between the tank and stand- I don't recall the type of material used, but I do recall thinking it was very similar to a rubberized yoga matt to avoid serious pressure points.

Id probably put it in the location where it belongs and let it acclimate, then instead of shimming it level, scribe the top and take off your excess with a belt sander. Throw in some pocket screws at your corners to insure against lateral movement so you don't get any wobble if someone were to slam into it. I cant see any of these warping sufficiently enough to get so out of square that it could ever collapse.

 

[BernieL]

You're best bet is to take it in and let it bend or whatever it wants to do... but I count 56 braces... that's a lot of holding power

 

[flytekk]

Wow you guys are amazing. Thanks so much for all the details. And yes there are 56 braces. Also may be hard to see in pic but there are 16 8" screws going through each long bar connecting to middle cross bars on either side, top and bottom.

The tank is not frameless it has black frame throughout.

Also i will skin this baby on the sides and back with 1/2" plywood screwed how ever ya want, to each vertical and cross as well as 1/4" plywood on top and bottom. I would even do 3/4" all around. I dont care. Just want this to work. Dont want to throw away.

Question with all that ply wood screwed to all the members, can the wood still warp? Wouldnt the ply hold it in place?

Also the screws in the L braces scare me now as ive read that the PT wood chemicals can eat away at it! GRRRRR The screws are galvanized but not sure if thats enough. Here are the braces it says, indoor/outdoor as well as steel, galvanized.

http://www.homedepot.com/p/Everbilt...er-Braces-4-Pack-15270/202033930#.Uh6-_xvrxf8

 

[flytekk]

Oh a little more information. The stand is currently in garage. Thats exactly where tank will be so the stand is already where it will be long term. Also i went ahead and painted the stand before i even knew of all these issues. I painted it black latex gloss paint and primer. 2 coats. Will this have any thing to do with the drying/warping/cracking process?

 

[Dave Paine]

Question with all that ply wood screwed to all the members, can the wood still warp? Wouldnt the ply hold it in place?

Also the screws in the L braces scare me now as ive read that the PT wood chemicals can eat away at it! GRRRRR The screws are galvanized but not sure if thats enough.

I do not think you appreciate the forces which can be generated when wood wants to move. If the wood wants to warp or twist or bow, it will do so.

The chemicals in PT may corrode the galvanized metal. The fact this is in a garage helps a lot, since it should not be seeing rain or snow, so only the present moisture in the lumber. I would not worry about the screws.

I still would be concerned at the overall construction with no real wood joints, but they is my personal preference.

The painting will slow down the drying of the lumber and so you will not see the wood movement issues as quick, but they will still happen over time.