Hello; I asked this question and will try to answer it to the best of my ability. I am currently running two test tanks to monitor the results and to test the quality of filters. Algone's website states the bacteria is the same -- refer to page: http://www.algone.com/fresh_to_saltwater.htm It is my opinion after 25 years of aquarium maintenance that this is the case also. I think the results of bacteria culture time and tank cycle time is tank specific. I fully beleive also that a cycled freshwater tank can be converted to saltwater and the cycle time will depend on the bacteria load of the substrate and filter only. I am running a test on two tanks and will post the final results when tank 1 cycles. Tank 1 - 10-gallon saltwater with Aragonite sand substrate -- 5-15 Aqua-Tech filter --- also a fully cycled Whisper 5-15 filter --- 5-lbs of FIJI live rock and a Corallife Super Skimmer with Needle wheel. Tank 1 is running ammonia 2-3 ppm and nitrite 2-3 ppm with nitrate below 10-ppm. The nitrate reading shows the tank has all the needed bacteria just not the needed quanties. Tank 2 - 10-gallon freshwater with 2-3 inches of Walmart epoxy coated gravel over an undergravel filter - pea sized - fully cycled for 6-weeks. Conversion today by adding salt -- 1-new Aqua-Tech 5-15 filter --- the tank was not heated so I inserted a Stealth 200-watt heater to bring the temperature up from 66-degrees to 77--degrees in less than an hour! Readings for tank two 1-hour after conversion to saltwater is ammonia 0-ppm, nitrite 0-ppm, nitrate 10-ppm. Temp on both tanks is kept close to 77-degrees. An equal amount and kind of fish food will be added to both tanks three times a day and the results reported back. Enjoy, Old_Fish_Man