I have a handle on other tank tasks that have been pressing, so now I need to attend to my problems with pH and Alk and am not sure how to begin. Problems: - Low pH - 8.1 in AM, drops to 7.8 or lower in afternoon, back to 8.1 by next AM. - Drop is backwards of what I expect, but this is in a classroom and as soon as students leave the pH starts increasing. So, too much CO2? Too little O2? Both? Should I try to measure ambient CO2? - Not enough photosynthesis happening in tank during the day? Should I have fuge light on during the day instead of night? - I totally need to clean and calibrate my Apex probes, but regardless the cycle is there. - Low Alk - at this point I don't even know the value. 6ish? Thought I loved obvious color change of Red Sea Pro something test kits. If anybody uses this... on the Alk/dKH one, the color changes from blue to rust on the card. Does yours turn gold/yellow instead? Do I read it just when the green is gone and it is yellow? I also have a less precise API KH kit I was going to have students use but I even have trouble reading that color change. - I have BRS 2-part dosers since summer still not set up. Supposedly not too difficult but will take time to read about it, set it up, find a place for reservoirs, see if I have Apex outlets, etc. This is why I never got around to it. Have been sometimes dosing by hand and trying not to increase Alk too much, but this spikes pH and I have not done it on a regular routine. I guess I have my answer - set up dosers; I think not interested in kalk at school. I have been really lazy and anxious about addressing these problems, but I need to get on it now. Man, it is really annoying to not have the tanks at my house. My choice, but frustrating nonetheless.