In one of my aquarium groups someone asked for advice about how to make an aquarium stand with wheels for a medium sized tank. Everybody else is going “try Home Depot” and “make sure you use heavy duty wheels.”
Not one of them has addressed the momentum/inertia issues involved with moving a fluid; especially in an open vessel whose lateral trajectory would be parallel to the length of the tank.
Can someone help me explain it better? TIA
When I was doing industrial plant equipment design back in the day I’d just reach for the McMaster-Carr catalog and see what they had to offer in the way of heavy duty casters. Now I’m happy to see that it’s online:
Better than stuff at Home Depot. Water is heavy.
You can clear the filter at the top and see all styles of casters.
Also I doubt that you will be moving a tank at high enough speeds to have to worry about momentum. Just getting it moving by hand would be a chore.
It’d be easy to show in small scale. Put a deep pot of water on the counter and give it a push.
Or just use one word: “slosh”.
ETA: the way I see this working well, and it may be a decent idea, is to have the top of the tank fully sealed for moving. Also, locking wheels for when the aquarium is on display.
Otherwise it’s a good way to have fish, water, and a big mess on the floor.
How big are we talking here? When I think of medium sized tanks I think if ones I’ve seen that can hold a sand shark, which are about 10 feet long x 4 four wide and big tanks are what they have in professional aquariums down the aisle from the huge tank.
That’s what I was thinking.
The thing about momentum is that it works whether you are going fast or slow; a moving object will have acquired momentum and have to disperse it through friction or some other mechanism before it comes to rest (in a particular reference frame, of course). That is why literal train wrecks are so fascinating; even if the train has been slowed, it has enough momentum that it will keep going quite a distance despite having derailed because it has to get rid of all of the momentum that it has in its great iron mass of pin-connected bogies.
Even if the tank is covered the water will slosh because it is a more-or-less Newtonian fluid, which will both lead to some very interesting non-linear dynamics when it comes to trying to arrest the motion (periodic surface waves interfering with one another will produce highly chaotic motion unless the tank is completely full and clamped tight under positive pressure) and havoc for the occupants and other materials in the tank. I don’t believe I’ve ever seen an aquarium on wheels intended to be moved while filled, and with very good reason aside from the fact that you wouldn’t want someone to push it onto a unsupported ramp or weak area of floor where it might break through.
Stranger
Part of the issue is the force of the water on the sides of an aquarium not built for “slosh”, right? You’ll get additional force, and potentially strain and warping in the aquarium itself. Professional aquariums must have set ups for this. You’d need to look at biology lab equipment, or similar professional level gear I would think.
Yep, and possibly a broken tank.
Why do they want to do this?
Lol I can see you’ve never tried to move an open full aquarium. The fuid dynamics are far more critical than the weight.
That’s kinda what I was thinking except the aquarium’s rectangular shape would amplify it further I think, no?
Completdly impractical to seal the top. If not impossible. And this isnt just a tank of nothing but water: it’s aquascaped anf occupied. An inter al wave would be like a tsunami
Exactly: the inertia > > momentum push to get it started will be cause the biggest slosh
Asking such questiins is considered starting an argumen; I’ get modded.
Sometimes asking such questions is a good idea, to get past the XY Problem.
Rather than asking how to make your chosen but difficult-to-implement solution work, how about asking how to actually solve the root problem, without being necessarily burdened by an impractical first guess at a solution?
Is this a FB group? Based on the “discussions” I see in such groups, a simply inquiry like that would be mild indeed.
A frequent question is how to move a tank to a new address, and aquarium owners are always advised to remove inhabitants and plants to transport separately, while draining water from the tank. Never saw anyone wanting wheels on an aquarium stand to (for instance) move a tank to another room, or to clean around it. Towing a wheeled tank on the Interstate to a new town could get tricky…
The problem is he wants to be able to move the occupied aquarium without breaking it down. Since there are literally zero practical, diy solutions, the “why” would go to motivation, so again not a useful question as it would lead to no solution and would almost certainly become an emotional exchange.
I found wheeled carts online for aquariums, and the suggestion was that it was to make it possible to move the aquarium away from the wall for servicing, or to a new location, after draining 2/3rds of the water. They’re solid steel and pricey, though.
I could see a slow move away from the wall or slowly moving to another spot with the aquarium mostly empty. Slow and steady, it seems reasonable.
Does the tank just have to move back and forth along one line? Or will it have to be steered around things like a grocery cart? If just back and forth - simple wheels will do. But, if like a grocery cart, at least two of four wheels would have to swivel.
I agree that momentum is the biggest enemy here, so a way to limit any jerkiness would be important. A motor with step-down gears driving the wheels would do that. A simpler method would be to manually move the cart using a lever with the bottom pivoting off the mover’s foot, and the lever pressing against the cart at the bottom. (A second-class lever) This increases the control - reduces the speed.
Well, if it has to be casters, use the biggest sturdiest ones you can get. (Larger diameter will have more tolerance for bumps that might catch and sigificantly decelerate a high-center-of-gravity mass on smaller wheels.)
Sturdy for dynamic stress tolerance in non-standard directions (i.e., pushing force).
And then, after the entire thing is put together, accelerate very slowly, which is the only way to mitigate sloshing.
If you really want to be inventive, and if the floor is smooth enough, make a hovercraft!