I have a Fluval 405 and with it I have 4 media baskets. I have read many times in this forum that old media should never be rinsed with tap water.

In my baskets I have sponges, pre-filter, and bio-max in the remaining two.
I never change both baskets of bio-max at the same time.

I do however rinse my sponges and pre-filter in tap. And only rinse my bio-max when it's a new addition.

I have a Python so it's impossible to rinse in used tank water while doing w/c. Because I have a python I seem to have extra 5 gallon (US) buckets lying around.

So my three questions are this ...
1. As long as I have one bio-max full with good bacteria, does it really matter that I rinse the rest in tap?
2. If I was to fill and keep one 5G bucket with water that has been sitting for days, to let the chlorine dissipate, but non-oxygenated water and rinsed in that, is that as goos as "tank water"?.
3. Or is there no difference because the bio is being kept with one basket?

I know that I "could" drain a few gallons into a bucket and perform what is recommended here, but this way seems to have been working so far. But I'm always open to newer and better ideas to keep my pets healthier.

when i service my filters i fill a five gallon pail and rince the bio media in it(i still use a pail and small gravel vac to clean my substrate then the python to drain and fill). for the sponges i rince them under the tap like you do. i have yet to have any ammonia spikes doing it this way.

I do wash my filter in tap water too... but I believe different location and water parameters had an effects on washing filters. As I go over and over with different review in this site, I find it difficult to decipher everything. What works for one may not works for others.

i allways wash anything from my tank in tank water. i allways just thought it was the best way and its easy to do:)