If you don’t already have a liquid testing kit, it is of great assistance to purchase one. You will want an ammonia, nitrite, nitrate and pH kit. For your reference, I’ve included a neat little graph to outline the cycling process.
The legends on this are not to be followed as far as level amount at stages of cycling.
A liquid kit will allow you to measure and track at what stage of the cycle you are up to. Cycling can take long than the legend indicates in the graph, so patience plays a part. At all stages you will want to ensure levels of ammonia or nitrite are not toxic enough to kill. We also want to ensure that the cycle is not stalled or lost whilst maintaining quality of water. Betta fish are relatively low wasters so ammonia may take a bit of time to form, it may be prudent to ‘seed’ the tank or filter if you have a friend or local fish store able to provide you with fish waste. This can kick-start your cycle.
For your tank, you should be able to allow a full week between testing, obviously the initial stage will be ammonia. After 1 week a 30-40% wc should suffice, when undertaking a water change disturbing the substrate/decorations whilst siphoning is advisable. Leaving the substrate undisturbed can build up ammonia and if disturbed after a period of time, can released an ammonia spike – very quickly poisoning betta. Before your first water change, measure the level of ammonia. Undertake the wc, then measure the ammonia level 48 hours later. Any measurement read immediately after a wc can be inaccurate.
Continue with your weekly 30-40% wc until you cycle through ammonia and nitrite. You will get to a point where you read ammonia and nitrite, this will mean you’re almost halfway – you won’t need to be concerned with Nitrate testing at this point. Then eventually you will reach a point in time where you test for ammonia and read zero, but your nitrite is continuing to read levels. At this point you can begin testing for nitrate.
Once your nitrite levels reach zero, and you have nitrate readings. You’re cycled!
If you don’t want to get a liquid kit, it’s kind of going to be target shooting with the lights turned off. You can stick with the wc schedule, but you’ll never be certain of at what stage you are.
Hope this helps.