Water Chemistry

I did all the tests I have, which now include Nitrate and Phosphate, and it almost makes sense:

	pH	dGH	dKH	CO2	NO3	PO4
58G	7.6	6.16	7.28	5.5	10	0.25
20G	7.6	5.60	6.16	4.5	5	0.25
Tap	7.6	3.92	5.04	3.8	2	0.25

Tests were done at around 6pm, 1 hour after CO2 was turned off in 58gal and 1-2 days after 50% water change. Looks like the water pH is too high for my pH Low Range (6.0-7.6) test. I need to get a high range test, better yet figure out how to lower the pH. It seems like topping off the tanks with distilled water might be a good idea. For now I decided to bubble CO2 into 58gal 24 hours/day instead of during the "lights on" hours only....