Does concrete raise PH?
I constructed a 3D background that has a protruding rectangular castle, bridge and tower. It is all made from a styrofoam mold out of quickrete concrete and spray painted with krylon fusion. I just replaced the gravel with sand which raised the PH to about 8.0
I heard that concrete can temporarily raise the PH. Does anybody know?
Comments
Yes it can because the cement in concrete contains lime, which can dissolve into the water, increasing the pH and hardness.
But if your tank pH is already around 8.0, it wont have much effect as the lime doesn't dissolve any more at that level. Therefore it wont go much higher.
It's if you put concrete in low pH water, it will tend to gradually boost the pH, until it gets close to 8.0, then the process stops.
Of course if it's well painted, then the water and concrete aren't actually in contact anyway, so nothing happens.
Ian
Concrete will temporarily raise the pH of soft neutral or acidic ( low pH) water for a few weeks. The surface of uncoated concrete will gradually be sealed by natural processes, including thigmotrophic bacteria that we want in the aqauarium anyway for their ability to convert ammonia and dissolved oxyfgen into nitrite and nitrate.
I grew up pouring concrete, and later on worked around concrete aquariums and helped build tank backgrounds for tanks up to 5000 gallons.
The Krylon Fusion paint is similar to marine paints and hobbyists have found it to be safe in their aquariums. It will peel off surfaces that are not clean or concrete that effloresces.(grows a white powder or white hairlike growth on the surface)
The is a lot of alkaline in concrete and it can raise PH. But, if you sealed it with Krylon fusion then it shouldn't be able to leech through, That's why Krylon fusion is the best for aquariums. It forms a hard seal and doesn't come off our leech, Maybe you didn't paint the back and it is leeching from there?