Copper level in QT dropping

[SifuMemphis]

I have a 20g Long QT tang, and dosing Cupramine and got it exactly at .50 (hanna checker) over the course of a couple days, I notice it drops slightly. What would be causing this drop? Is there something in the tank that is absorbing it?

Equipment :

20G Long Tank
150 Watt Heater
Koralia pump
Sponge Filter (air bubbles)
Ceramic media (a few balls / Plate from my DT tank -- Marine Pure block)
3 PVC tubes for hiding
ATO unit for water evaporation

Attached is a image of the tank.

Any thoughts?

 

[Big G]

The Hanna has an error range of + or - 0.05

 

[SifuMemphis]

The Hanna has an error range of + or - 0.05

So at that point, if it reads 0.5.. but drops to 0.44 ot 0.45, which would I believe is correct? I assume I would just keep testing to see the average range?

 

[Big G]

So at that point, if it reads 0.5.. but drops to 0.44 ot 0.45, which would I believe is correct? I assume I would just keep testing to see the average range?

Therapeutic range of Cupramine starts at 0.35 ppm so you are good in the 0.5 range.

 

[CK00020]

Not to sidetrack you but I have the same problem but dosing copper power, had to to 1.0 the next morn .83. I figure the sponges sucked it up?

 

[SifuMemphis]

Therapeutic range of Cupramine starts at 0.35 ppm so you are good in the 0.5 range.

Oh interesting. So as long as im within 0.4-0.5 i am good? I read that if it ever drops below 0.5 , the "timer" resets

 

[Big G]

If it drops below "therapeutic levels" the clock starts over. Which is 0.35 for Cupramine.

 

[TAL]

FWIW, my friend has used copper a few times in a 10g tank and the copper has decreased every day to where the dose needed increased to remain therapeutic. It may be common for it to drop some.