I'm not stressing over the chem levels of the new 20 - I put on 2 'cycled' filters - one was sitting as a 'doubled' filter on my 30 gallon for over a month - a tank with gouramis, boesimani, tetras, and a king betta. The second filter was remaining cycled - also acting as a double filter - on the 20 gallon high, that housed 4 sorority girls, 3 cories, and 7 neons.
The two filters - when I moved them over, I rinsed out their pre-sponge, but didn't rinse their matrix media.
On top of all that, the tank is planted with an organic soil substrate (plenty of bio-load in that) - as well as with a good portion of live plants.
If there was a mini-cycle - which is possible, in doing the switch over into the new tank environment - but, since both filters are very well seeded - I'm not expecting there was any cycling problems.
Currently, that tank has only 7 bettas in it - since I moved several out to put them into Camelot.
TheJewels... 20 g H plantedsorority - 4 princesses & 3 zebra otos
Ladies of Camelot - extended visit of Rome - 7 pretty girls & 7 cories - 20G Long.
Gawain - hM (2.5 g planted tank)
Lancelot - hM (5 gallon tank)
Roland - CT (5 g)
Galahad - deltatail (15 gallon divided)
King Richard the Lionheart- king betta (12 g Camelot)
Tristan - VT- (15 g divided)
Robin of Locksley (20g H w/threadfins/neons)