Ph And Hardness

[PDSimon]

I'm a bit confused about my tank...

I know people can sucessfully run tanks at really low pH's(less than 6), but how does this differ from when you're fishless cycling and a low pH stalls the cycle?

I ask because when I add my bogwood to my tank, in 24 hours it can bring the pH down to 6 - its quite a steady 6 but I don't see how you can go from one day to stalling at 6pH (which I have..) to it being fine at 6 pH just because there are fish in there?

Any help is much appreciated...

Note:

tap water is
6GH
3KH
7.4-5pH

edit: I would actually like a pH of 6-6.5 because I want to stock south american fish but what about when I do waterchanges, won't changing 25% raise the pH suddenly stress the fish?

 

[meguro]

fish adjust to pH in about 15min. 25% water change at slightly different pH wont cause much of a shift

 

[PDSimon]

You consider 6 pH with a water change of 25% 7.5 pH water to be ok?

thats good...Thanks for the reply

edit:

do you think if I add fish and bogwood on the same day it'll be ok... because I added the bogwood the day before I was going to add fish and my pH dropped and the cycle stalled... so unsure of what to do