12. After any adjustments from 11, repeat the tests to make sure the concentrations are where they should be. WAIT 4 more weeks! Now start checking the phosphate concentration.13. Slowly add your clean-up crew from quarantine. Add all snails, including some carnivorous ones. Feed them according to what they need to eat. (Feed herbivore snails with sheets of marine algae; feed carnivore snails with shrimp flesh, scallop, squid, clam, etc. but no pellets yet). Do not add starfish or cucumber at this point. Don't add any obligate detritus eaters.
14. Run aquarium with the clean-up crew being fed and kept healthy for a few weeks. Then, if all water chemistries and water parameters are still good, add shrimp, additional worms and pods you'd like to keep. Feed all your livestock every two days. At this time, you can include the feeding of pellets that sink.
15. Drop a clean, opened, previously frozen and thawed living clam into the aquarium once every 10 days. You should see worms, carnivorous snails, and the shrimp eating it. Remove any uneaten clam 20 hours after putting it in.
16. After no less than two months of running the aquarium with the clean-up crew in place with proper, steady water quality the appearance of the aquarium should be coming around. There should be less noticeable 'brown algae' and nuisance algae. The clean-up crew can be expanded along the way as needed. Snails may be laying eggs (a good sign), pod population should be very high, and worms are perhaps more noticeable (they are getting brave since there are no worm predators around -- yet!).
17. Determine the foods needed for the fishes you want to keep. Obtain proper nutritional supplements and foods and get things ready for handling fishes.
18. Acquire your first (hardy) fish to put through the quarantine process.
19. Start adding hardy fish to the display aquarium at a rate no faster than one fish every 6 weeks. Monitor all chemistries and if anything goes out of sorts, stop adding fish, determine any causes, fix causes, make additional water changes, etc. before continuing. CHOOSE YOUR FISH WISELY.
20. After the first fish is added, you may quarantine a Chocolate Chip Star separately to be added to the display. Same with a cucumber. The QT for the cucumber can have a thick substrate laden with food particles during quarantine. Choose one or the other for aquariums over 165 gallons. Now is the time to add any obligate detritus eaters.
21. After several (6-8) months of operation after the clean-up crew was put in, the tank should be mature and ready for more sensitive fishes (the large Angelfishes, Butterflyfish, etc.). If the goal is to keep these kinds of fishes, then let the tank run with the clean up crew, shrimp, etc. and regular feedings for these critters, for no less than a total of 6 months.
22. Don't overstock. Stick to your plan.
23. Add fish one at a time with no less than 6 weeks in between so the system can adjust to each addition. The system needs time to gear up to additional bio-loads and demands put on it.
-At the risk of a Joe like calling out, this is from Lee Birch.
Basically you are starting fresh. The rock in the 150, what just that, established for the specific bioload of that tank. In the 265gal, everything will need to start fresh. There's no way to import over all of the pods, worms, beneficial bacteria that only time will allow to become established in an aquarium.
However the main reason is there's a difference between a tank ready for clean-up-crew/hardy specimen, and a tank ready for a blue-spotted stingray.