Best time of day for a water change

**Matsyendra** · 09-23-2011, 02:23 AM

Perhaps someone has already thought of this.

This morning, I got up nice and early to do a 50% water change and to do a quick rearrange of the placement of some of the plants. Re-dosed KNO3 and PO4. Sitting back now and enjoying my tank.

After the water change a thought occurred to me. It seems that maintaining steady levels of CO2 throughout the photoperiod is one of the surest ways to help prevent possible issues (re: algae).

Is this correct - on changing water you are driving out some of that CO2 with increased surface agitation? Whilst some CO2 is replaced with the water change, my drop checker definitely shows a difference in CO2 level today 3 hours after water change, than what was indicated from the day before, or even immediately before the water change when I turned my lights on!

So here is my thought and suggestion. It makes most sense to do the water change immediately before lights out. This way the plants are not affected by the sudden drop in CO2 and the levels can rebuild overnight to optimum, in time for lights on photoperiod the next day.

Has this occurred to anyone else?

**Biollante** · 09-23-2011, 02:32 AM

Hi All,

In my ever-humble-potted-plant-opinion, the best time is when the automated system kicks in!

Actually, there probably is a slight advantage to one time over another, I think whenever someone will is the best time.

I think I probably could make a case for almost anytime, being superior to another…

I will give this a think…

Biollante

**Gerryd** · 09-23-2011, 04:35 AM

Any time is a good time for a water change

**AquaticJim** · 09-23-2011, 04:51 AM

I do mine always around 3 hours before lights come on. It's just a routine that suits me

**Tom Barr** · 09-23-2011, 06:23 AM

I do mine about 1-2 hours after the lights are on, then the tank jams all day.............

**dutchy** · 09-23-2011, 08:54 AM

Just after lights on.

**charlie** · 09-23-2011, 09:51 AM

Originally Posted by AquaticJim

I do mine always around 3 hours before lights come on. It's just a routine that suits me

X2, in combo with a nice shot of Excel

.......to the tank that is.

**jaafaman** · 09-23-2011, 11:28 PM

Quite a few of the places I've lived that were in the tropics/subtropics tended to rain at times in the afternoon you could almost set your watch by, so I kinda got in the habit of making the changes in the late afternoon after getting home from work...

**Jim Miller** · 09-23-2011, 11:33 PM

Plants in the wild are subject to "water changes" at all hours of the day and night. My suggestion is just do it when you can without disturbing everyone else rather than picking some "plant optimal" time.

Make it a time when you can enjoy doing some trimming or moving of scape material. Should be enjoyable rather than a treadmill!

Jim (taking a break from a massive trim. see blog for reason why!)

**Matsyendra** · 09-24-2011, 03:16 AM

I guess no-one really cares and it is probably not important at all. Fair enough it was just an observation and thought.

Whilst I appreciate that plants in the wild are subject to water changes at odd times, it happens that our plants are not in the wild and are subject to the application of increased dissolved CO2 in the water column that perhaps they do not have available to them in the wild?

As so many issues are directly linked to CO2 I just thought it would make sense to minimise the impact.