Hebdizzle
08-31-2003, 10:02 PM
What is it in a SW tank that makes the PH ~8.2? Is it the sand? live rock? salt?
Thanks for helping out a newbie :)
Aaron
g. mcclean
09-01-2003, 2:25 PM
Natural seawater has a pH of 8.0 or higher. When we use the saltwater mix we are simulating natural seawater. Synthetic seawater contain buffers also. The substrate is also critical for maintaining the correct pH.
mogurnda
09-01-2003, 5:05 PM
Yep. Both natural and artificial seawater are buffered by the same dissolved compounds electrolytes, predominantly carbonate and borate. The reserve of these buffers is what you're measuring when you measure alkalinity.
There are several factors working to reduce your tank's buffering. The production of CO2 and nitrate by your pets has a tendency to acidify the water and reduce your "alkali reserve." Carbonate is also required for building coral skeletons and snail shells, so it has to be replenished in a tank with invertebrates. Other factors, such as the presence of macroalgae, can push the tank toward a higher pH.
Although it's really a complex topic, water changes help a lot to keep things where they should be. In my experience, if you keep your alkalinity between 3 and 4, the pH will take care of itself.