Hello WTM,
It would be nice to know your real name - more friendly
ok this is probly what your problem is as I am from upper hutt too.
there is bugger all ph buffer in our water , so when you get just the slitest amount of nitrate in your tank ( nitrate = acid ) it will cause your ph to drop from 7 to well that depends on the level of nitrate it could get really BAD if you don't keep up thou's water changes .
there is 2 ways to fix
1, do a 5% water change 5 to 6 days a week = 30% over the week
2, add buffer to your water . this is what I do, I do 1 as well :lol:
how to add buffer to your water
1, find a small piece of dolmite rock ( if you can find some, tell me I want some )
it works like this the acid in you tank desolves the lime until the ph hits 7 then it is nutralised ( or close to it )
2, add half a teaspoon of sodium bicarbonate ( = baking soda ) per 100lt , you must add a % of bicarbonate every time you do a water change to keep your ph balanced
adding this amount will give you a final ph of around 7.2 to 7.4.
if you use method 2 DON'T add all the b/soda at once just add a % every water change and in 2 to 3 weeks at a 30% water change per week your tank will be fully buffered .
any other ideas people? more the marryer