Cycling a 720 Gallon System, Couple questions...

[Hendre]

You will definitely get a spike when you add two huge rays. If you have an other sump or something to help seed your system that is ideal. Or go buy a bunch of big cheap fish and through them in lol. The rotting fish I don't like as it can introduce fungus and bad bacteria.

Try Seachem Stability, I cycled my 20gal in 4 days with it, I am not entirely sure if it is safe to put in with fish? Maybe that will work

 

[DN328]

Seachem Stability is safe for fish and could help boost BB. I also would use Prime for additional support when adding additional stock. Especially helpful if you get a spike. It would help to neutralize ammonia and nitrite. Given the size of your tank it will take a lot if you follow the recommended dosage.

Do you have substrate and other things in your tank? All that counts as things that can home BB as you likely know. Good luck.

 

[Hendre]

That