Water changes

[Puffydave]

I've kept tropical fish for over 10 years now and other family members longer, with great success .
I've only ever done about a 25% water change once a month with no problems and healthy water conditions, 0 nitrate and 0 nitrite.
Now, I've been reading that puffer keepers are doing 50% water changes once a week!
This seems to much to often to me, surely this is not allowing any good bacteria to establish itself in the filter? And keeping the salt levels, PH etc right even harder?.
I've got a 5ft tank, with 3 F8 puffers and 3 orange chromide's and after 3 weeks with no water changes the PH is still 7.5, salt 1.005 and nitrate and nitrite levels on nothing, 0.
I do clean the gravel once a week to suck up any mess other then that all is good..
Will keep checking water quality and any signs of it going down hill will do a change.
What's people views on this?.........
Still think 50% every week is over the top and will do more harm then good

[nzac]

are you sure your test kit is accurate? unless full marine or very, very, very heavily planted, there should always be some nitrates in a cycled tank. That being said I have a couple tanks that get 50% weekly waterchanges (heavily stocked) but most are 25% weekly (single fish in large tank). Doing a waterchange does not affect the bacteria colony in the filter, that is based off the bioload of the tank. Also keep in mind there are other things that build up in the water (tds, hormones, etc) that most people don't measure for that still build up over time and can change the chemistry of your water.

[Welch4]

+1 to the above. Especially in regards to the nitrate. I'd recommend taking a water sample to a LFS to test. I do 40-50% weeklies.

[Pufferpunk]

I do 70-80% weekly on my FW tanks. Have been for a very long time. I'm not sure how taking water & & replacing it would affect the bacteria living in the filter?