I just had a quick question about the substrate to put in the new 5gal I have... would it be ok to mix the sand I have left from my 30gal with a bit of standard gravel?
it would be a good idea because the sand in the 30 gal is established i am assuming and this would help jumpstart the cycle in your 5 gal. The substrates will seperate over time, but there isn't anything wrong with it. Just make sure the 30 gal is disease free atm or you could contaminate the 5 gal