I used to advise holding out for the occasional total water change (hoping the new tap water would be enough of a rise in pH) when the pH really pushed you to it... but I've grown to like the rather more artificial approach where once you see several of the signs (definately seeing a several degree ph drop but also seeing nitrites spiking and hopefully nitrates going up some too.. all signs of truly getting in to the nitrite spike stage) you go ahead and to a total down to the gravel change (gravel-cleaning it out) and then, in addition to remembering to recharge the ammonia, you dose baking soda at 2 teaspoons per 50L and later see it that takes the pH on up to 8, dosing a bit more if it stops short of 8. I just have not seen any bad reports from members who have dosed bicarb (baking soda, not baking powder) and I trust more and more that it just all goes out with the final big water change and leaves no minor problems.
~~waterdrop~~
