White film on glass

[Krismo962]

Everytime I do a waterchange this white film forms on the glass and it makes my tank look cloudy from the outside eventhough the water is clear . Any idea what it could be? When I scrub it off it comes off like white dust.

 

[A201]

The white dusty stuff is likely calcium carbonate.
My tap water is hard & does the same thing to my tanks.

 

[duanes]

Calcium carbonate, and bicarbonate precipitates out at pH 7.5 or above, and may show up a white film.
What are your water parameters (tap water and tank water) before and after water changes. (hardness, pH, etc)
What is your normal water change schedule?
A little more info to go on would help determine cause etc.

 

[Krismo962]

Calcium carbonate, and bicarbonate precipitates out at pH 7.5 or above, and may show up a white film.
What are your water parameters (tap water and tank water) before and after water changes. (hardness, pH, etc)
What is your normal water change schedule?
A little more info to go on would help determine cause etc.

5ppm nitrate,0ppm ammonia,0ppm nitrite (tank) 90% water change every 2 days,haven't tested the tap water yet though. ph is around 7.7 - 7.8(tank) I haven't got any addictives or anything to buffer the ph.
I don't mind cleaning the glass after water changes just want to know if it's harmful or not.

 

[duanes]

That's a great water change routine, so it sounds like normal calcium precipitation, should not be a harmful.