Okay, so I have now planted the second-hand 10G tank from Goodwill - everything seems fine clarity-wise, ammonia level is 'safe' and filters all working nicely. On the advice of my local aquarist retailer (Angels and More, Muncie - a husband and wife business run by keen and knowledgeable aquarists), have placed 6 zebra danios in it to help develop the water chemistry. The store even buys back fish at 50% if I decide to change the species in the tank once the setup is established. They talked me out of buying more expensive fish!
Anyway, added the danios yesterday (Saturday) and they seem happy as Larry. 2 females and 4 males, I believe. Will monitor levels and then I will add more small fish over the next couple of weeks if all goes smoothly - probably just a couple of corydoras and some serpae tetras.
The danios are good eaters, barely a flake even settling on the bottom of the tank and if it does, it is soon gone! I am feeding very small amounts only.
Added 1/4 cup of Ammo-Chips to the hang-on-back filter, having removed the carbon. Added Stress Coat and API Leaf Zone prior to adding fish. Also added some darker (washed) gravel to give the UG filter a chance (there was barely a half-inch with the plate showing in several places), now between 3-4 inches deep.
Here's some pics so far.

Anyway, added the danios yesterday (Saturday) and they seem happy as Larry. 2 females and 4 males, I believe. Will monitor levels and then I will add more small fish over the next couple of weeks if all goes smoothly - probably just a couple of corydoras and some serpae tetras.
The danios are good eaters, barely a flake even settling on the bottom of the tank and if it does, it is soon gone! I am feeding very small amounts only.
Added 1/4 cup of Ammo-Chips to the hang-on-back filter, having removed the carbon. Added Stress Coat and API Leaf Zone prior to adding fish. Also added some darker (washed) gravel to give the UG filter a chance (there was barely a half-inch with the plate showing in several places), now between 3-4 inches deep.
Here's some pics so far.



