100 gallon multipunctatus tank

[Bas Pels]

You keep Cardinals in a tank for Synodontiws multipunctatus?

Cardinals come from the Rio Negro, pH around 4. The can be kept at pH 7, but Tanganjica fish like a high pH 8.5 or 9. Far too high for cardinals. Or the other tetra´s shown

Further, the wood in the tank might not be ideal. Wood lowers the pH, unless it is old and inactive. It is rather hard to buy old wood, but you might have the wood voor quite a while. I certainly cannot see whether it is old or not.

In a Tanganjica tank, it is a good idea to buffer the pH, with chalck. this also hardens the water, but your fish will not mind. chalck can be gotten cheaply at a place for cickenfood, it´s the stuff chickens eat it for their eggs.

[Boris]

You keep Cardinals in a tank for Synodontiws multipunctatus?

Yes (neons)! I know that these tetras have the opposite requirements compared to tanganyikans but I am rather certain that they are not wild caught but farmed for generations in whatever water the fish farm had. They have lived in this water for over two years together with that piece of wood and I have measured pH and hardness regularly. My tap water is soft but pH is raised by the water plant to protect the pipes from corrosion. Adding crushed coral to the sand raised the hardness a couple of degrees.

Is chalk better than bicarbonate for buffering and what hardness should I aim for? The species page for multipunctatus says pH 7,8 - 8,2.