Something white on glass bottom

[aerialdronemaster]

Helo guys

I am finishing cycling. I noticed something white in my sump, like a white powder, I can white it with my hand.

Is it alkalinity residue? I started dosing a lot to keep the right level .

It was also on glass but I had to scrub it .

 

[jordan10]

Why are u dosing alk if it tank is cycling?

 

[aerialdronemaster]

The cycling is done, the water i bought had everything low, all, cal and magnesium so I had to increase it , before I add any corals fish.
The white residue is also on WaveMaker, some of them I can remove easy. Some I need to brush