test water with lights off ?????

[Vincent100]

can i test for these with my dt lights off , iv a light on in my sump

magnesium
alkalinity
calcium

thanks

 

[Elementalj]

Test both day and night. Alkalinity and pH move around during light periods.

 

[NanaReefer]

Actually there's not a big enough difference between day/night to matter. Find a time most convenient to you, choose acceptable numbers and then shoot for stability. So yes testing at night is fine.

 

[Randy Holmes-Farley Verified Community Expert]

None of those necessarily vary day to night.

They do vary due to consumption, dosing, water changes, and evaporation.