I’m addicted - Cycling Help

So I have my 20 gallon tall aquarium that happily houses a small school of harlequin rasboras, two plates, and a male and female guppy. This tank has a tetra HOB double filter that is oversized. I also have a small 5 gallon whisper filter that I added for additional biological filtration. The five gallon filter only has sponge media in it. The larger double filter has filter cartridges that are intended for it along with two bags of ceramic bio beads, and another 3 or 4 biological sponges that I tucked in there. I have a 10 gallon setup that I added a new filter to, some plants, and basically mimicked my 20 gallon (just smaller in size). I don’t really want to take out the five gallon filter, because it creates nice movement and my tank is crystal clear. My question is this? Can I remove a sponge or two from my larger HOB filter and add it to my HOB filter in the new 10 gallon aquarium? I am thinking of moving my male guppy into that tank (we already have babies) and adding a school of harlequin rasboras. Initially I was going to add the male guppy and purchase 3 or 4 harlequins. Will this make sense bioload wise? I don’t want to crash my 20 gallon, but I’d also like to help cycle my new 10 gallon. I planned on adding the same Tetra bacteria that I think really helped me cycle my 20 gallon to the new tank as well. I do daily water tests with my API kit. My 10 gallon without fish has been tested:

PH 7.8
Ammonia 0
Nitrite 0
Nitrate 0

Any pointers would be appreciated. In summary:

Move a few sponges from 20 gallon filter to 10 gallon filter.

Move my male guppy and possibly purchase 3 harlequin rasbora’s for my 10 gallon.

Continue daily API testing on both tanks (daily makes me feel better).

How many harlequin’s (once I’m fully cycled) can I have in my 10 gallon?

 

No problems and honestly it should be how you do things considering you already have a fully cycled tank. The only reason not to would be cross contamination. If you take your time adding new stock to the new tank, don't even consider it "help cycling". You should be able to skip that whole process altogether if you take your time and do things correctly.
The only reason to add ammonia instead of stock is if you can't add stock for whatever reason.

 

Would the one guppy and three harlequin’s be okay to start, or would it be too much? Also how many should I have for a fully stocked tank when it comes to that.

 

Your best chance for success is frequent testing and frequent water changes. You'll see what's going on with your test readings. You'll probably be changing water every day for a while, but pretty soon the water changes are less frequent. Testing and doing water changes is the most important thing you can do.

I'd also recommend logging your test readings. It's interesting to watch the curves.

BTW, moving filter media is fine because you're already testing the water and doing water changes. Whether it's too much or not enough you can't predict, but the testing is valuable information. Usually moving some filter media will provide seed bacteria, but you still have to keep an eye on it until the biofilm covers everything.

BTW #2. You show zero nitrates. That's not a normal nitrate reading for a cycled tank. A cycled tank would be something like, 0 - 0 - 10 (or 20, or whatever). How long have your tanks been set up?

 

Thank you, I actually keep a spreadsheet of my readings for the purpose you stated.

Your best chance for success is frequent testing and frequent water changes. You'll see what's going on with your test readings. You'll probably be changing water every day for a while, but pretty soon the water changes are less frequent. Testing and doing water changes is the most important thing you can do.

I'd also recommend logging your test readings. It's interesting to watch the curves.

BTW, moving filter media is fine because you're already testing the water and doing water changes. Whether it's too much or not enough you can't predict, but the testing is valuable information. Usually moving some filter media will provide seed bacteria, but you still have to keep an eye on it until the biofilm covers everything.

BTW #2. You show zero nitrates. That's not a normal nitrate reading for a cycled tank. A cycled tank would be something like, 0 - 0 - 10 (or 20, or whatever). How long have your tanks been set up?

These readings are for the tank without fish. My established tank has the following readings:

PH 7.8
Ammonia 0
Nitrite 0
Nitrate 10 PPM last night, I’m due for my weekly PWC tomorrow. Typically my nitrates stay below 20 PPM because of my weekly PWC’s.