What you are seeing is the buffer effect or KH
. If you keep adding PH
down you will depleat the buffer and then all at once the PH
will crash. It is best to not use chemicals to lower PH
. Better to let the fish get used to your water.
I am pasteing this from another site. http://www.netmax.tk/
German for Karbonate Hardness, also known as temporary hardness, buffer or alkalinity. Measured in ppm
or degrees (divide ppm
by 17.9), aquarists usually refer to how many degrees of buffer they have (dkH
). Water with a low buffer is more susceptible to problems with pH instability. Any pressure on the pH, either from materials decaying (acidifying, causing the pH to drop), or from rocks leeching (adding calcium carbonates causing the pH to rise) will be more effective when the buffer is low. This can have undesirable effects in the normal routine of materials decaying (fish waste, dead plant matter, uneaten food etc). It is recommended to keep your buffer above 4dkH, and to be careful if your source water is normally below 4dkH. The effect of acidification it to consume the buffer, before affecting the pH, so as soon as the buffer is zero, pH swings will occur. While baking soda will boost kH
without significantly affecting gH
, the usual treatments for low buffer are to do more water changes, gravel vacuum more and add calcium carbonate leeching stones into the tank or filter.
Measured on a logarithmic scale, neutral water is defined as 7.0pH. Anything below 7.0 is defined as acidic, and above 7.0 as alkaline. A pH of 6.0 is ten times more acidic than 7.0 pH. Fish generally come from a pH range of 6.8 to 8.4pH, with several species coming from even greater extremes. Ideally, small fish should not be exposed to more than a 0.25pH change per day, while larger fish will tolerate 0.5pH per day. The ability of a fish to adapt to changes depends a lot on its size and condition.
It may be desirable to naturally soften your water and add some tannic acids (almost essential for breeding some species). Driftwood, peat moss, Terbang and Oak leaves are all commonly used for this purpose. Recipe depends on material being used.
There are chemical means to acidify water (highly acidic solutions). Chemical methods have a tendency to either produce no pH changes (while exhausting the buffer) or cause a very significant pH drop (after buffer has been exhausted). For this reason, chemical methods should only be used in storage containers (or aquariums without fish) while slower natural methods can be used in the aquarium with fish (with some monitoring).