Is it possible to keep live rock and have a captive reef in a Rubbermaid tub? Yes, maybe, and no ? It all depends on the types of critters.
About ten months ago I was faced with a dilemma. I had 20-25 pounds of Haitian live rock I needed to remove from my 75 gallon frag tank, but I did not have a spare tank. One option was to buy a cheap tank to house the rock. Another was to use a spare Rubbermaid tub. I went with the zero cost option.
My Rubbermaid Reef Tank
I placed the rock in the Rubbermaid and added established saltwater from my 200 gallon reef tank system. A spare power head was used to keep the water circulating. The Rubbermaid is 37 gallons in total but only a third is filled with water…so probably 12 gallons of saltwater. On rare occasions I remove a gallon of water and replace it with established water from my tank. I also add RO/DI water 1X a week to replace water lost due to evaporation.
I was curious about the water parameters so I conducted some tests. The results confirmed I had a decent environment to maintain a crude reef.
Salinity: 1.026 sg
Nitrate: 50 ppm
Phosphate: .35 ppm
Alkalinity: 7.3 dKh
Calcium: 410 ppm
Magnesium: 1380 ppm