In the bottom of those RubberMaid tubs there's two long indentations that the long stones sit in real nicely. The last ones I've used are crappy compared to older ones made by the same outfit.. Only get bubbles from part of the stone or lots of huge bubbles.
I'm going to try making my own from that black garden hose that 'weeps' water out. Already have one of those in my dugout connected to a 1/2' airline that runs underground from my basement to the dugout with the water line. Need to put on a new one and already have one in the shop. I just cut the faucet end off and use a hose clamp to attach it to the airline. All coiled up from the store with a weight tied on with a long nylon tie. Need to borrow a boat or get a new tube for my belly boat to get out there and replace the old one. Have a grapple made out of rebar to fish it out of the 12' deep water.
I used my neighbour's small aluminum rowboat to put a hose on and flipped it over tossing the dog out because he was barking his fool head off at some ducks in the bullrushes. Half-pissed too so that didn't help. Had my steel-toed runners on from work and damn near drowned my sorry ass. Had to get the belly boat to rescue the rowboat.
I figure I can buy some of that SS cable from the hardware store, wash with methyl hydrate to remove any oil residue, and put a length of it inside a piece of that hose to weigh it down. Plug one end and use a threaded nylon fitting with the right size barbed nipple on the other end to connect my airline. Got to work as good as those $6 aquarium stones. Make it about 2ft long so it lies in a big U shape on the bottom. If it plugs up just replace the piece of hose to rebuild it. Cost me $14 for a 50ft hose that I could make 25 'stones' from so that's cheap like borscht!