Time of day to test kH

[Avonlea,PA]

I just installed a pressurized CO2 system. I was wondering what time of day I should test for kH (or any test for that matter). I only dose while the lights are on, which is from about 9:30am to 6:30pm.

[wetmanNY]

KH doesn't rise and fall during the day.
pH rises and falls during the day.
Same time each day gives you something to compare.

[djlen]

I check pH first thing in the morning just as I'm turning on the lights and late in the afternoon while I still have good daylight to compare colors to the color chart. Your kH will not fluctuate during the day. Once you know it you can check it from time to time to see if it's changed.
A question for you. When you say you only dose when the lights are on, I assume you're talking about dosing CO2. If that's so, why? I run my CO2 24/7 and the only drop I see in pH over night is .1 - .2 at the most.
IMO, it's as stressful on the fish when the pH swings toward alkaline overnight, which is what happens when you turn the CO2 off at night, as it is the other way when you don't. And you may see a larger swing up depending on the type of filtration you're using.
Len

[Skittyfish]

Djlen, I turn off my CO2 at night and still only get a swing of .1 at the most. If you don't have turbulance at the surface then very little CO2 escapes at night. Or at least this has been my experience.

[Avonlea,PA]

Originally posted by djlen

A question for you. When you say you only dose when the lights are on, I assume you're talking about dosing CO2. If that's so, why?

Yes, I'm talking about the CO2. I've read that if you dose during the night, the pH swings. I'll have to take a look at mine when I get home from work at midnight. Right now it's at 6.8. It also helps a bit on the electric bill, since I use a Duetto filter as my reactor, plus an electronic solenoid. I know it's not much, but every little bit helps.

Sorry for the ignorance with kH. I thought since CO2 affects the kH, then it would stray a bit if not dosing 24hrs a day.

Here is another question: Now that I've added the CO2, I rearranged the output of my Fluval so it does not disturb the surface as much. What about the "scum" that appears on the surface. Is this bad? It looks mostly like some small bubbles from the CO2 that haven't popped, but there is also some other "stuff"

[djlen]

Ah Skitty, those cannisters are wonderful aren't they. Little surface movement = little gas-off.
Avonlea, you have to find the workable amount of movement in the tank that will cut down on surface scum and yet keep the CO2 gas off to a minimum. It's a balancing act.
Len

[Avonlea,PA]

Originally posted by Avonlea,PA
I'll have to take a look at mine when I get home from work at midnight. Right now it's at 6.8. It also

pH was still at 6.8 6 hrs after the lights were out. Now, I did just begin adding the C02, and right now I'm adding 1b every 2 seconds. Maybe if/when I adjust the amount of C02, there will be a nighttime swing. I guess I'll just wait and see.