hi guys/gals
Changes in the pH ( as in a drop in pH ) is a pretty good indicator that there is an insufficient alkalinity level in the tankwater.
pH is just a number that relates to the amount of H+ hydrogen ions in the water. It's partner is the OH- hydroxyl ion.
When they meet you have H+ plus OH- , they get together and form HOH ( otherwise known as H2O water )
At a pH of 7.0 the number or amount of both of these ions are relatively equal. The water is considered to have a neutral pH.
At pH levels above 7.0, you have more OH- (base) and less H+
At pH levels below 7.0 you have more H+ (acid) and less OH-
In a saltwater aquarium - as acids are produced or added to the tank - naturally the pH will begin to drop.
In addition to the OH- ions, there are carbonates, bicarbonates and other base salts in the water. These compounds are known for neutralizing the acids as well, but go through a little bit different chemical reaction.
The amount or level of these carbonates is called the alkalinity, or sometimes referred to as the buffer capacity.
If the alkalinity is too low - the acids build up and are not neutralized. Acids contain H+
So there is a build up of H+ ions, and again the pH will begin to drop.
Think of it like playing a table board game with another player.
The other player is called acid guy.
Your game name is acid guy neutralizer.
The object of the game is to not let acid guy win by matching every coin he tosses into the pot on the table.
Acid guy has acid coins.
You have acid neutralzing coins - pennies.
You have a stack of pennies in front of you. Each penny can neutrlize one of his acid coins. He tosses an acid coin into the pot ( tankwater ) Each time you toss a penny into the same pot - you neutralize one of his acids. If you run out of pennies - you're done - and can't neutrlize anymore of his acids. The pH then will begin to drop. Acids make the pH drop.
Acid guy begins to win.
Think of the alkalinity as your wallet. If it looks like acid guy is going to win, and your stack of pennies starts getting too low in front of you - you can reach into your alkalinity wallet and cash in a dollar bill. Now you have more pennies in front of you to keep playing the acid neutralizing game with ole acid dude.
Your wallet is "buffering" the game table pot ( tankwater ), by allowing you to have more pennies ( acid neutralizers ) to keep playing against the acid guy.
Your pennies neutralize the acids. Your dollar bills "buffer" your ability to keep neutralzing the acids. If you begin to run out of dollar bills - your alkalinity is low. You must then add buffers ( more dollar bills ) back into the wallet ( tankwater ) to keep the pH from dropping and keep playing.
You get more dollar bills from the bank ( marine buffer products and alkalinity builders ).
If you don't go to the bank to get more alkalinity dollars, and you run low on bills again ( carbonates, buffers ) then the acid guy starts to win again, and the pH will again begin to drop.
Man - I'm not sure if that makes any sense at all now that I re-read it ...... but I'll let it ride.
Sorry for such a long screwy reply