water qualityt

Question
I have a 55 gal freshwater planted community tank (mostly tetras)keeps going acid and nitrates going a little high.I can help stabilize ph with dead coral but water goes too hard,I have heard about marble chips,I am wondering about their effect on water. ie hardness, toxicity.

Answer
Hi Doug,
Water hardness has nothing to do with nitrogen.  If your nitrates are getting high, the only way to get rid of it is by water changes or by a densely planted tank.  Also, crushed dead coral is used to raise the pH.  Tetras do not like high pH, they actually prefer low pH, soft, acidic environments.  The species that prefer hard water with crushed corals are certain Cichlids.  

Beneficial bacteria breaks down ammonia into nitrite and then nitrite into nitrate.  Nitrate can not be broken down by bacteria, therefore must be removed by the 2 ways I mentioned.  Marble chips I believe is also for cichlids.  I would suggest an inert substrate or a substrate that lowers the pH and softness of the water such as ADA Amazonia Aqua Soil.  ADA AS is also the top of the line for planted tanks.  It is basically the Mercedes of substrates.  

Good water quality = frequent water changes.
-Matt-