Precipitate on heaters and sump glass

[Spectral_Ranger]

Am in the process of relocating my sump, and found this tan precipitate all over my glass heaters (especially around the heating coil area). There's also some on the glass walls of the sump, but none in the display tank itself. I'm assuming this is calcium precipitating (calcium carbonate?). I don't know if it still is now, or there as some event that caused it. I did start 2 part dosing a couple months ago, and might have had some swings where I had high alk and Ca. Right now, I'm pretty steady at 9.5 dKH and 480ppm Ca (and 1400ppm Mg). What conditions would cause this precipitation? Would like to avoid it again if at all possible... Didn't have any livestock issues, though.

 

[bertoni]

That does look like calcium carbonate. If so, it'll fizz in vinegar. You could reduce the calcium level to 400 ppm or so, and that might help with the precipitation rate. Also, getting more flow over the heater might be appropriate, since calcium carbonate forms more easily as the temperatures go up.