Sorry to hear about Flash. Amazing how fond we grow of them.
How long is it since you moved Flash out of the 10g?
And have you just had the snail in there since then?
The reason I ask is because a cycled tank has colonies of beneficial bacteria (as you know).
But those colonies need to be fed, or they start to die off.
So if you had a tank cycled with 1 betta and 1 snail, as soon as the betta was removed, then the beneficial bacteria started to die back until they were the right size to process the waste from your snail.
Does that make sense?
There is a saying that ‘your cycle is only as good as the number of fish’.
So a tank that is cycled for 5 fish isn’t cycled for 10 fish.
And a tank that is cycled for 1 snail isn’t cycled for a snail and a betta.
However, there is a very simple way around the problem :)
All you need to do is add your new betta, and keep an eye on ammonia and nitrate levels, stepping in with water changes and dosing with Prime, daily, if a mini cycle starts off from the additional bio-load.
If you lucky, the existing beneficial bacteria will adapt very qickly, and you won’t have a problem. Adding a single betta to a 10g tank isn’t like adding a shoal of rasboras, so the rise in bio-load won’t be much. But it is still worth keeping a close eye on ammonia levels, just in case.
Hope that helps.
: (Kham) mature setup; betta, purple rasboras, amano and wood shrimp. Heavily planted.
22litre cube tank
: (Tagawa); betta, 1 amano, yellow dwarf shrimp. Pond snails and 1 assassin. Heavily planted.
57litre cube tank
: ember tetras, 2 amano, 1 nerite, pond snails, 1 assassin, doing his thing. Heavily planted.
; honey gourami, cherry barbs, green neons, otocinclus, nerites, pond snails, amano. Heavily planted.