rinsing with tap?????

Not all tap water is filled with phosphates. I would be curious to see how much phosphate would be absorbed by sand or rock if rinsed in it. That seems to be a common conception, but it hasn't been backed up by any real evidence. (Soaking aside) Once you add salt water to the tank, the phosphate should move into the solution. If it is bound by the sand some how, then it's not an issue either. Although I guess it could slowly leach into the water. But how much could possibly leach? IMO, no more then when you feed your fish by a long shot. However, I don't know if it would even remain in the sand or not, I guess I need someone to perform an experiment.

 

you just dont want to be dumping tapwater into the tank i.e topoff etc. you can use it to rinse/clean equip.