A few instant to semi instant cycle products work.
Seachem Stability is the most readily available one that works but it takes a few days longer then the more expensive products.
I rate them in this order
Superbac (expensive 1 liter = 20 bucks and it cycles about 100 gallons instantly aka I dont see any spikes of anything, make sure it hasn't expired)
Instant Ocean Bio Spira just like the above but only for marina applications
Seachem Stability - It works but slowly compare dot the above (aka cycle is done in a week). It can stress out your fish as you will see some ammonia and some nitrite. I use it with fish less cycling and it does its job perfectly, I just wouldn't use it to cycle a tank with say my Puffer in it since its too slow.
All in all each one is great!
Seachem Stability is the most readily available one that works but it takes a few days longer then the more expensive products.
I rate them in this order
Superbac (expensive 1 liter = 20 bucks and it cycles about 100 gallons instantly aka I dont see any spikes of anything, make sure it hasn't expired)
Instant Ocean Bio Spira just like the above but only for marina applications
Seachem Stability - It works but slowly compare dot the above (aka cycle is done in a week). It can stress out your fish as you will see some ammonia and some nitrite. I use it with fish less cycling and it does its job perfectly, I just wouldn't use it to cycle a tank with say my Puffer in it since its too slow.
All in all each one is great!