I am in the first week of cycling and I believe the white material on the surface of my lava rock is hard water as the water evaporates, but thought I might ask. I was having a low ph issue, so started adding some potassium carbonate and now have ph at 7.4, ammonia is at 4.0. I'm having to add 3 - 4 gallons of top off water (have treated to get rid of Chlorine) per day and my air temp is at 90 F lately. Anything to worry about? I have a system inside my home that doesn't need topping off but about a gallon a week and no white stuff. Water temperatures in the outside tank are 78 F and 72 F inside.
Did you see this post in the forum?
I was having the same problem.