help with my PH swing/kalk dosing

[thin crust]

hi everyone

i've been trying figure out a way to maintain a steady PH level. currently i dose DIY 2 part solution on a daily basis. CA is at around 390 and ALK is at 2.5. i notice that my PH will drop to 7.9 overnight night. i usually can bring it back to 8.3 when i dose my 2 part solution in the morning.

i've set up a kalk dosing unit in use with my ReefKeeper2 controller. i have it set to turn on if PH drops to 8.20 and off at PH 8.25. the issue i'm running into is the kalk water is being added faster than the evaporation rate. this causes my water level to go too high. my tank is only 25g so i don't have much room.

should i increase my PH controller range so it doesn't dose so often?

or is there a bigger problem i need to address as to why my PH swing is so big during night time?

thanks in advance for your advice

TC

[coraljunky]

With an alk reading at 3.5 meq/l your calcium should be near 430ppm.
http://home.comcast.net/~jdieck1/chemcalc.html

[thin crust]

correction, it's at 2.5. sorry still a little hungover from last night. :P

[coraljunky]

I had the same issue until I raised my alk and calcium. Now I maintain ph@8.35 alk@9.6dkh cal@430-440ppm

[bertoni]

7.9 isn't that bad, and I probably wouldn't do anything. Dosing kalkwasser based on pH is not a good idea, and I'd expect the resulting SG fluctuations to do a lot more harm than marginally low pH. Moving the alkalinity up would give a small boost in pH and should be safe, though.

[thin crust]

thanks coraljunky and bertoni for the advice. i'm going to work on bringing my ca/alk levels up a bit and hopefully get it dialed in.

happy 2008!