Howdy,
To answer the original Q: No problem, unless you have plants. Crypts sometimes prefer old water. Unless your tap water has 10-20 ppm nitrates, faster growing plants may require add'l nitrogen fertilization (i.e fish waste accumulation). That's just two examples.
Re: pH and feeding: The theory is nice and well, but only pans out in reality in tanks that are unmaintained mud puddles. I.e. not here.
HarleyK