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Maintenance during photo period

bushaaayyy

Member
Joined
25 Dec 2020
Messages
71
Location
Warwick
My photo period runs from 4-10pm with co2 running 1-9pm. I read somewhere that it’s best to do water changes outside of the photo period to avoid fluctuating co2 levels.

But with a 3 week old baby I’m now finding it hard to always find the time to do my maintenance in the mornings. Do others do their water changes during the photo period? Will it really have that much of an impact on plant health, algae growth etc.

also unrelated question, but when is it best practice to trim stem plants? Wait until they are nearly reaching the surface or sooner than this.
 
My photo period runs from 4-10pm with co2 running 1-9pm. I read somewhere that it’s best to do water changes outside of the photo period to avoid fluctuating co2 levels.
Hello,
The advice is a general rule that may or may not apply. For CO2 injected tanks it's better to do the water change before the light go on or just prior to the gas being turned on simply because most municipal water supplies have the water enriched with CO2. This CO2 is an added boost to the CO2 that will be turned on and you will often observe that when done this way the plants will pearl more easily than on days where no water change is done.

For tanks that do not have injected CO2 this issue is much less critical and is simply a rule of thumb. CO2 added during the photoperiod may increase the chance of getting some forms of CO2 related algae s the CO2 from the water change is added and then dissipates. For non-injected tanks suffering BBA for example it may be a good idea to follow the rule of thumb in order to help alleviate the problem, but if the tank is not having any of these issues then it can be ignored. Plants have some adaptability, so different tanks will have different experiences.
But with a 3 week old baby I’m now finding it hard to always find the time to do my maintenance in the mornings. Do others do their water changes during the photo period? Will it really have that much of an impact on plant health, algae growth etc.
As stated, do what you need to do. See how it goes. It is simply a rule of thumb and does not cause the tank to fall off the cliff if not followed.
also unrelated question, but when is it best practice to trim stem plants? Wait until they are nearly reaching the surface or sooner than this.
This is an aesthetic choice. Trim when you want to. If the scape in your minds eye requires the stems to be a certain height then keep it at that height. If you prefer the plants to reach the surface then do it that way. The more you trim a stem plant the bushier it becomes.

Cheers,
 
But with a 3 week old baby I’m now finding it hard to always find the time to do my maintenance in the mornings.
@bushaaayyy Congrats on the baby! :)
simply because most municipal water supplies have the water enriched with CO2. This CO2 is an added boost to the CO2 that will be turned on and you will often observe that when done this way the plants will pearl more easily than on days where no water change is done.
Hi @ceg4048 To what extent will an RO unit remove the CO2? (I'm wondering if perhaps if a CO2 molecule is too big to slip through the membranes).

Cheers,
Michael
 
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Presuming evetthing timed to come on so say the day you want to do your water change unplug your CO2 solenoid so the gas cant come out if you are working around your new arrival (congrats🙂)do any maintenance when you can. I dont think it will do much harm to have a shorter photoperiod if needed.
 
Hi @ceg4048 To what extent will an RO unit remove the CO2? (I'm wondering if perhaps if a CO2 molecule is too big to slip through the membranes).
Fill a container with the amount of water you use for the water change and leave it standing for 24hrs. this should allow any Co2 to dissipate.
 
Hi @ceg4048 To what extent will an RO unit remove the CO2? (I'm wondering if perhaps if a CO2 molecule is too big to slip through the membranes).
Hi Michael,
Yes, CO2 molecule is too large to fit through the membrane, so if using RO water for the water change there will not be any CO2 present, so this can be taken out of the equation. Also note that not all municipal water supplies have CO2. As I'm sure you're aware it's very simple to test by measuring the pH straight from the tap and letting it sit for an hour or so before taking another reading. As the CO2 dissipates the pH will rise.

Cheers,
 
Hi Michael,
Yes, CO2 molecule is too large to fit through the membrane, so if using RO water for the water change there will not be any CO2 present, so this can be taken out of the equation.
Hi @ceg4048 , Thanks for the answer.
Also note that not all municipal water supplies have CO2. As I'm sure you're aware it's very simple to test by measuring the pH straight from the tap and letting it sit for an hour or so before taking another reading. As the CO2 dissipates the pH will rise.
Interesting. Yes, I will try that to see how much of a difference I see here with my tap water. I am wondering if the CO2 enrichment is for disinfection purposes?

Cheers,
Michael
 
I was also in your position last year. Change when it’s convenient for you. What I do now is keep my Co2 off the day I’m doing the change, and my lights off as well. Us dads have variable schedules so if that means the tank stays dark until I do the water change, so be it! I resume usual CO2 and light schedule the next day. Just makes it easier for me.
 
I have to do my maintenance during the day during the photo period. The compromise i made was to do a half length photo period that day. I'd let the tank run for as long as I could normally then I'd cut the lights, do my water change and then leave them off for the rest of the day. The 3 hours of growth per week that I missed out on was negligible. Lately though I've actually tried just leaving the lights running and dropping the water low enough that my plants are emerged for a while and can access some atmospheric CO2. I haven't noticed any difference in growth.
 
Just to add lets assume on the day you do a w/c subsrate debris removal maybe plant trim and possible filter clean . Your photoperiod starts say 2pm your lights come on 4pm off at 11pm .It takes all or most of the morning to do the work. If for any reason that is delayed yo can leave it that day or just change water if possible do other things spread out over the week. Like filter and plant work I think healthy plants are resilient we know that when doing a short blackout on the tank
 
The good news is you're overthinking it. If you're doing weekly water changes then just change the water when it's convenient for you. Your plants won't know/care if they get a little less CO2 for half a photoperiod once per week. For example, I went on holiday for two weeks, turned off the CO2 for the whole time and nothing obviously bad happened: Two week holiday - no problem | Fireplace aquarium. If you have an otherwise healthy set-up it will be reasonably robust and forgiving. That's also what I like about EI dosing - not too picky with fine details.
 
Interesting. Yes, I will try that to see how much of a difference I see here with my tap water. I am wondering if the CO2 enrichment is for disinfection purposes?
Hi Michael,
Often, CO2 dissolves into the water supply simply due to the path that the water takes through aquafers on it's way to the municipality. Since it readily reacts with water to form the weak carbonic acid it is added by some water companies to reduce the pH (or the company injects carbonic acid directly which then produces dissolved CO2.) Many times the water flows through underground carbonate sources such as limestone caves so the carbonic acid helps to reduce limescale buildup throughout the transfer pipe system. As you surmised, downward pH adjustment is also useful in the water treatment processes such as chlorine addition and so forth.

Cheers,
 
Hi Michael,
Yes, CO2 molecule is too large to fit through the membrane, so if using RO water for the water change there will not be any CO2 present, so this can be taken out of the equation. Also note that not all municipal water supplies have CO2. As I'm sure you're aware it's very simple to test by measuring the pH straight from the tap and letting it sit for an hour or so before taking another reading. As the CO2 dissipates the pH will rise.

Cheers,
Hi @ceg4048 Yep! I tried this yesterday with our tap water in a mug (2 measurements before and 2 after using my API pH kit) - it distinctly went from somewhere between 7.0 - 7.2 to around 7.6 after about an hour. Not sure if that's a big jump or not, or anything about the level of CO2 enrichment can be deduced from this.
Cheers,
Michael
 
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Hi @ceg4048 Yep! I tried this yesterday with our tap water in a mug (2 measurements before and 2 after using my API pH kit) - it distinctly went from somewhere between 7.0 - 7.2 to around 7.6 after about an hour. Not sure if that's a big jump or not, or anything about the level of CO2 enrichment can be deduced from this.
Cheers,
Michael
Hi Michael,
Well, you maybe can get an idea of the amount of CO2 dissolved in the same way as the pH profile by looking at the difference in the CO2 values on the pH/KH/CO2 chart. Again, we would have to make the assumption that the rise in pH is due 100% to the dissipation of CO2. We would also have to make the assumption that the alkalinity of your water is due 100% to carbonate/bicarbonate (can you see how thin the ice is that we are skating on?). So lets say your taps KH is 10 (measured by you cheesy "KH" test kit) and all of that 10 alkalinity is actually due to carbonate (CO3).

If these assumptions are satisfied then at a KH of 10 and pH of, say, 7 the chart reads 30ppm. At pH 7.6 the chart reads 7.5
The difference is: 30ppm-7.5ppm = 22.5ppm.

If the KH of your water is 4 then the difference is 12ppm-3ppm = 9ppm

Again, this is all theoretical, mainly because although we can be fairly confident that the change in pH is strictly due to CO2, we are less confident that the source of the water's alkalinity is strictly due to CO3. There are a half dozen ions not named carbonate that affect alkalinity. The infamous chart assumes that only CO3 is causing the KH in the water sample.
Fair enough, those other ions have much less of an impact, but it's an assumption nonetheless.

Cheers,
 
Hi Michael,
Well, you maybe can get an idea of the amount of CO2 dissolved in the same way as the pH profile by looking at the difference in the CO2 values on the pH/KH/CO2 chart. Again, we would have to make the assumption that the rise in pH is due 100% to the dissipation of CO2. We would also have to make the assumption that the alkalinity of your water is due 100% to carbonate/bicarbonate (can you see how thin the ice is that we are skating on?). So lets say your taps KH is 10 (measured by you cheesy "KH" test kit) and all of that 10 alkalinity is actually due to carbonate (CO3).

If these assumptions are satisfied then at a KH of 10 and pH of, say, 7 the chart reads 30ppm. At pH 7.6 the chart reads 7.5
The difference is: 30ppm-7.5ppm = 22.5ppm.

If the KH of your water is 4 then the difference is 12ppm-3ppm = 9ppm

Again, this is all theoretical, mainly because although we can be fairly confident that the change in pH is strictly due to CO2, we are less confident that the source of the water's alkalinity is strictly due to CO3. There are a half dozen ions not named carbonate that affect alkalinity. The infamous chart assumes that only CO3 is causing the KH in the water sample.
Fair enough, those other ions have much less of an impact, but it's an assumption nonetheless.

Cheers,
Hi @ceg4048 Thank you for explaining this. Yes, I can see how we can be led astray with all the uncertainties.
Cheers,
Michael
 
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