Keep an eye on buildup!

[authentic]

Recently cleaned my sump and found a large amount of calcification directly under my tubing.
Cleaned it off and pointed a small pump under to create a high flow area.was dosing 10ml of alk daily.afterwards checked my alk daily and it kept rising from 8.5 to 11 even though I was decreasing my dosing.most must have been stopped before entering the water column.tank looks great but I like my alk lower in the 8 to 8.5 range

 

[Randy Holmes-Farley Verified Community Expert]

It is certainly desirable to dose to a high flow area.

That said, it doesn't always eliminate calcification.

This buildup is from where I dosed limewater for a long time, and even though there is a lot of flow, there is also substantial deposits (which don't concern me, actually).

Figure 4. When limewater drips onto surfaces, such as the sides of a sump, precipitation of calcium carbonate takes place. The off-white coloration probably comes from metals such as iron binding to the calcium carbonate surface in the place of calcium.

 

[Ocelaris]

Is there a concern with dosing into the same location after a deposit has occurred, for example at the bottom of the sump? i.e. is it more likely to precipitate if there already a crystal matrix (if that is relevant) to attach to? I watch all these BRS videos about the precipitation process latching onto other molecules, and worry I should go clean out my sump! I have stopped the over dosing, but worried existing dosing may be "attracted" to that spot?

 

[Randy Holmes-Farley Verified Community Expert]

How would you dose to the bottom? It should drip through the air and into the water.

The deposit is chemically no different than live rock or sand in terms of precipitation, although when it is fresh it nucleates better than when it ages and gets other crap on the growing crystal surfaces, slowing precipitation down.