Do I have to put old filter media into my new tanks filter, or can I just put the media in the substrate.

[Obsessed with fish]

I could not find an answer on google, sorry for all the questions btw. I upgraded from a 15 gallon to 23-gallon aquarium. In the 15 I had a sponge filter rated for 10 gallons and a hang on the back rated for 15 gallons. The tank was 3 years old with fish. I transferred all ornaments and 25% of the substrate to the new 23 gallon, I also transferred the sponge filter rated for 10 gallons, and I put about 1/3 of the media from the hang on the back into the new tank, but I just put the media in a pile in the tank, not in the filter, because I could only put a small amount of media in the sponge filter rated for 20 gallons that came with the tank. It is stocked with three oto's, 5 Sterbai Corydoras, 4 neon teras and 2 honey gouramis. It is heavily planted. Will my fish be ok or is the tank not cycled properly. Thanks in advance! I will test my water when I get home, which would be 18 hours after the transfer from my 15 to 23, i will let you know what my water parameters are in 1-3 hours. Thankyou again!

 

[Colin_T]

Are you keeping both tanks set up?
If yes, just transfer half the media from the old tank to the new one. Because you have two filters in the old tank, you can simply move one onto the new tank and leave the other behind.

If you aren't keeping both tanks running, then just move the old filters into the new tank.

Disregard filter for tank sizes, that is rubbish. You get a filter based on the number of fish you have and how much food you put in the tank. Also the type of fish and how much water movement they need. You have tetras, Corydoras and gouramis, all of which are slow water fishes and they don't need lots of water movement so you can have a small HOB filter on the big tank and it will do the job.