Water change before, during, or after photoperiod

Joel Armstrong

Joel Armstrong

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Hi,

I am curious about people's preferred time to perform a water change.

Before, during, or after the photoperiod?

Or perhaps it doesn't matter?

If a water change is done during the photoperiod, would CO2 saturation catch up quick enough to not cause any issues?

Would love to hear people's thoughts.

Thanks 😊
 
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Hey Joel,

That is a good question. My preference is before. I don't want to disturb things during the time the tank is in high energy mode. I suppose afterwards would also be fine under my thinking.

That said, I have done it during the photoperiod when I had no other choice. I don't think doing this for an hour or two will negatively impact the tank too much and things will quickly come back to normal. However, if you have the option, I would recommend you do it before.

Best,

Art
 
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I do my water changes right in the middle of the photoperiod for convenience. I keep my filters and co2 running the whole time (inline diffuser with spraybars). That plus doesn’t incoming tap water contain co2? (I thought I read a recommendation from Tom Barr to not do large water changes in low tech tanks because the incoming jolt of co2 is not desirable)?
I would think that with all that, the fluctuation in my tanks would be minimal.
 
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Thank you for your responses.

I have been doing my water changes before CO2 turns on for the day. I've also read somewhere that @plantbrain mentions water changes during, or shortly after the lights turn on.

As always, thank you for your thoughts, and looking forward to hearing a little more on this topic. 😀

Cheers
 
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You get the most out of the process by driving growth really hard that day. If a little after the lights come on, then the plant's biochemistry is really jamming along fast. Say about 45-60 minutes after the lights come on. Think of like you when you 1st wake up, you are a bit slow and sluggish. After some food, a walk, stretch etc, you are feeling a lot better. Uptake rates from pre dawn to midday are available for most common submersed aquatic weeds. See figures 2 for light as the sun comes up.....and then figure 6 for CO2 uptake as a function of Light intensity. I know 2 of the authors personally, Haller got me the job with the state. Figure 6 also shows how one species, say Hydrilla, can really outcompete and beat up all the other plants if the CO2 is sub par. Quite a lot of information comes out this paper. Way back in the olden days of 1976, Ford was the outgoing president and Carter had just been elected. Comparison of the Photosynthetic Characteristics of Three Submersed Aquatic Plants 1
 
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You can also try both methods, but unless you measure O2 with a meter or something, it may be tough to assess which treatment produces a better response. Prob not huge deal frankly. As long as you do them frequently and consistently, that's the real problem with aquarist, we are the biggest problem and cause of issues. We are inconsistent.
 
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plantbrain said:
You can also try both methods, but unless you measure O2 with a meter or something, it may be tough to assess which treatment produces a better response. Prob not huge deal frankly. As long as you do them frequently and consistently, that's the real problem with aquarist, we are the biggest problem and cause of issues. We are inconsistent.
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Agreed.

I've done them before the lights come on, while lots are on, and after the lights go out. I have not seen a difference in how plants react.

As Tom said more importantly is that you do them. Good consistent maintenance creates a stable clean environment and makes everything else easier.
 
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Well, unless there's something else I'm not aware of, I tried doing water changes during the photoperiod and I ended up with some hair algae.
I had kept everything else in the tank the same.

My tank is just a little over 12 months old, and I've never had any hair algae.

My tank is 120cm x 60cm x 60cm and I do 75% water changes, they take me about 2 and a half hours to perform the water change.

pH drop is 1.5 by the time lights come on, and my tank takes 3 and a half hours to reach this pH drop.

I'm returning to my previous routine of performing water changes before the CO2 turns on, or after the lights have turned off.

If my tank takes 3 and a half hours to reach CO2 saturation, wouldn't it be counter-productive to remove 75% of the CO2 laden water and replace with tap water during the photoperiod? Resulting in hair algae??

Perhaps it's the length of time I'm taking to do the water changes maybe?

In any case, I think I'll return to my previous routine.

I'd be interested in hearing your thoughts.

Cheers
 
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Art said:
Hey Joel,

That is a good question. My preference is before. I don't want to disturb things during the time the tank is in high energy mode. I suppose afterwards would also be fine under my thinking.

That said, I have done it during the photoperiod when I had no other choice. I don't think doing this for an hour or two will negatively impact the tank too much and things will quickly come back to normal. However, if you have the option, I would recommend you do it before.

Best,

Art
Click to expand...

Perhaps it's the length of time I take to perform a water change, but I agree with what your saying. I'm no where near experienced as most of the folk here though... I guess I'm missing something 😕
 
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I always do a wc on Saturdays. I use to get up early so i can do a wc. Yah, that got old lol! Dont really want to do it after the CO2 shuts off since, well, cuz its Saturday. Now, I dont even inject CO2 on Saturdays and the lights are at about 40%. Air pump is on all day too. Smart plugs and programmable LED lights makes it easier. I just do the wc whenever that day. Been doing it this way for a couple months now.
 
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Joel Armstrong said:
my tank takes 3 and a half hours to reach this pH drop.
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Joel, may I ask you about this? To me, that's a really long time. I get down to 1.6+ drop within 30 minutes.

I realize that my drop may be a bit fast for some but it works for me. I start pumping CO2 30 minutes before lights come on so I have enough concentration by the time the plants start to photosynthesize.

Are you starting to pump CO2 3.5 hours before lights? I guess, why does it take so long?
 
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Art said:
Joel, may I ask you about this? To me, that's a really long time. I get down to 1.6+ drop within 30 minutes.

I realize that my drop may be a bit fast for some but it works for me. I start pumping CO2 30 minutes before lights come on so I have enough concentration by the time the plants start to photosynthesize.

Are you starting to pump CO2 3.5 hours before lights? I guess, why does it take so long?
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It depends on the size of the tank as well as surface agitation.

Higher surface agitation, ie outgassing, gives a faster ramp up and better stabilisation - be it at higher CO2 consumption.

Bigger tanks take more time.

The injection rate needed to maintain a 1.0 pH drop is roughly proportional to the tanks surface area, while the time the tank will need to ramp up from fully outgassed to 1.0 pH drop is dependent on the surface area (continuously losing CO2 through outgassing) as well as volume (load the water column with 30 ppm CO2).

A trick for bigger tanks is using dual reactors for ramp up, yet only one reactor continues to maintain the CO2 constant during photoperiod. Alternatively a pH/CO2 controller can handle a fast ramp up for a bigger tank, but this involves a bit more risks when a failure occurs.
 
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Art said:
Joel, may I ask you about this? To me, that's a really long time. I get down to 1.6+ drop within 30 minutes.

I realize that my drop may be a bit fast for some but it works for me. I start pumping CO2 30 minutes before lights come on so I have enough concentration by the time the plants start to photosynthesize.

Are you starting to pump CO2 3.5 hours before lights? I guess, why does it take so long?
Click to expand...

Hi Art,

I'm more than happy for you to ask me, I'm willing to get tips from the more experienced, and would like to optimise my methods.

Currently, the CO2 comes on 3 hours before lights come on, it was 3.5.
I do end up with a gas bubble in the reactor towards the end of the photoperiod.

I do have quite a bit of surface agitation, and the surface area of my tank is 120cm x 60cm.

The tank itself is 120cm x 60cm x 60cm.

Testing with a Milwaukee pH56 pro pen.

Testing degassed tank water, I'm getting a reading of about pH 7.43.
Water in tank before CO2 kicks on is pH 7.0
After 1 hour, tank water is about pH 6.25 and drops further to pH 6 over the next 2 hours, when the lights come on. Another hour or so after the lights come on the pH drops a little further to 5.9 where it seems to stay.


I'd really like some help if I'm doing something wrong, and greatly appreciate any feedback and advice.
 
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Yugang said:
It depends on the size of the tank as well as surface agitation.

Higher surface agitation, ie outgassing, gives a faster ramp up and better stabilisation - be it at higher CO2 consumption.

Bigger tanks take more time.

The injection rate needed to maintain a 1.0 pH drop is roughly proportional to the tanks surface area, while the time the tank will need to ramp up from fully outgassed to 1.0 pH drop is dependent on the surface area (continuously losing CO2 through outgassing) as well as volume (load the water column with 30 ppm CO2).

A trick for bigger tanks is using dual reactors for ramp up, yet only one reactor continues to maintain the CO2 constant during photoperiod. Alternatively a pH/CO2 controller can handle a fast ramp up for a bigger tank, but this involves a bit more risks when a failure occurs.
Click to expand...

Hi,

I'm considering getting a pH/CO2 controller actually.

Appreciate any feedback
 
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Joel, so your degassed water is 7.43? That's pretty high. What is the GH/KH that you're running? I'm assuming that is your Australian tap water?
 
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Art said:
Joel, so your degassed water is 7.43? That's pretty high. What is the GH/KH that you're running? I'm assuming that is your Australian tap water?
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Hi Art,

Yeah, Australian tap water, KH is around 3, according to water report Ca is 16ppm and Mg 1.5ppm. I've been adding 5ppm Mg

Cheers
 
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