Low Light With Pressurized Co2 Question - The Planted Tank Forum
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post #1 of 11 (permalink) Old 07-06-2020, 07:37 PM Thread Starter
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Low Light With Pressurized Co2 Question

I finally got a pressurized co2 system after 10+ years of yeast/sugar DIY. I'm really enjoying it. I should have gone pressurized from the beginning.

My question is how much co2 should I target for low light? At the moment I'm aiming for 10ppm. According to the Rotala Butterfly Calculator, with my KH of 5, I need to drop my Ph from 7.6 to 7.2.
Is 10ppm a good amount to max out growth in low light? I did some research and I found people recommending anywhere from 5-15ppm.

Thanks
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post #2 of 11 (permalink) Old 07-06-2020, 08:25 PM
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10-15 should be good in low light, IMO!
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post #3 of 11 (permalink) Old 07-07-2020, 12:58 AM
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Ten years! You're more of a masochist than I was (most that I could take was a year of DIY).

I would expect that the 10ppm area would be fine. However, I would tend to want to test the limit, since you don't really know how much light (PAR,PUR and photoperiod) you're delivering. To do that, and assuming KH is constant, I would start at a .3 point pH drop from fully degassed (make sure you let some tank water stand out several days to know fully degassed pH). Then, two weeks later, I would increase CO2 so that you would get a .6 pH drop and compare growth a week later to see if plants are noticeably improved from the .3 pH drop. Keep doing this until you reach desired plant growth/health. to measure in these type of increments, you should get a pH pen as opposed to the liquid type of test kits.
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post #4 of 11 (permalink) Old 07-07-2020, 05:51 PM
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If you have a heavenly planted aquarium you shouldn’t have to inject any CO2 during the night. Remember your plants are living organisms which will consume oxygen during the because the lights are off and they are not carrying out photosynthesis. Thus, they will consume oxygen and produced CO2 as well as your fish. This is why it is recommended to have a timer on your CO2 unit so that the injection is stopped during the night. Now as far as your Ph dropping or going higher it has to do with carbonic acid. Fluctuations of oxygen and carbon dioxide within the water column during the day or night cycles directly affect Ph levels and hardness of the water.

These changes are called diurnal fluctuations and occur in nature within the different water ecosystems these plants and fish are found throughout the world. As the plants photosynthesize, carbon dioxide levels in the water begin to drop and the amount of carbonic acid produced also falls. The release of the oxygen will also bind organics and minerals, and combined with falling carbonic acids, this causes pH levels to rise ( become more alkaline.) Therefore, like stated before at night, plants cease to photosynthesize and stop producing oxygen, although they continue to respire. This has the effect of reducing oxygen levels in the water. The dissolved carbon dioxide will bind both with minerals such as Calcium, creating bicarbonate that raise water hardness and buffering levels, and with organics, creating carbonic acid that will lower pH. During a 24 hour period these processes have the effect of raising oxygen, hardness, and pH levels during the day, while lowering levels at night.

So to answer your questions you shouldn’t have to intervene in a process that your plants are already doing naturally.
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post #5 of 11 (permalink) Old 07-08-2020, 03:05 AM Thread Starter
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Quote:
Originally Posted by fermentedfunk View Post
10-15 should be good in low light, IMO!
Super! I it's currently at 15ppm. Thank you.

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Originally Posted by Deanna View Post
Ten years! You're more of a masochist than I was (most that I could take was a year of DIY).

I would expect that the 10ppm area would be fine. However, I would tend to want to test the limit, since you don't really know how much light (PAR,PUR and photoperiod) you're delivering. To do that, and assuming KH is constant, I would start at a .3 point pH drop from fully degassed (make sure you let some tank water stand out several days to know fully degassed pH). Then, two weeks later, I would increase CO2 so that you would get a .6 pH drop and compare growth a week later to see if plants are noticeably improved from the .3 pH drop. Keep doing this until you reach desired plant growth/health. to measure in these type of increments, you should get a pH pen as opposed to the liquid type of test kits.
Hahaha! I guess it wasn't too bad because my use of DIY was on and off. I still can't believe I didn't do this sooner.
I think I started on the higher end of the scale. I'm at 15ppm. The indoor lighting made it difficult to see the color on the API test tube last night. This morning, after a few hours of injection, I checked it by the biggest window at home and what I thought was 10ppm last night is actually 15ppm. Down to 7.0 from 7.6.
I'll stick with this setting for now as everything is going well and fish are fine.

I'm on day 3 and I'm seeing a big difference. I think I have to adjust my ferts now. So far, I had to dose a little more iron and nitrate today.

Thanks for the tip on the ph pen. That should come in handy. I'll check the lfs because I'm planning to buy a TDS pen as well.

As for getting the proper PH/KH, is it the same as leaving my tap water out for a couple of days instead of aquarium water? I've checked my tap before and it was identical to the tank. Maybe I should check again.

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Originally Posted by Backblast72 View Post
If you have a heavenly planted aquarium you shouldn’t have to inject any CO2 during the night. Remember your plants are living organisms which will consume oxygen during the because the lights are off and they are not carrying out photosynthesis. Thus, they will consume oxygen and produced CO2 as well as your fish. This is why it is recommended to have a timer on your CO2 unit so that the injection is stopped during the night. Now as far as your Ph dropping or going higher it has to do with carbonic acid. Fluctuations of oxygen and carbon dioxide within the water column during the day or night cycles directly affect Ph levels and hardness of the water.

These changes are called diurnal fluctuations and occur in nature within the different water ecosystems these plants and fish are found throughout the world. As the plants photosynthesize, carbon dioxide levels in the water begin to drop and the amount of carbonic acid produced also falls. The release of the oxygen will also bind organics and minerals, and combined with falling carbonic acids, this causes pH levels to rise ( become more alkaline.) Therefore, like stated before at night, plants cease to photosynthesize and stop producing oxygen, although they continue to respire. This has the effect of reducing oxygen levels in the water. The dissolved carbon dioxide will bind both with minerals such as Calcium, creating bicarbonate that raise water hardness and buffering levels, and with organics, creating carbonic acid that will lower pH. During a 24 hour period these processes have the effect of raising oxygen, hardness, and pH levels during the day, while lowering levels at night.

So to answer your questions you shouldn’t have to intervene in a process that your plants are already doing naturally.
Thanks for the informative post! The co2 is off at night and turns on 1 hour before the lights. The oxygen level at night should be pretty good. I have 3 hob filters with the water line up at the filter output creating a lot of surface agitation.

I guess it's a good idea to keep an eye on KH regularly. I'm curious how much of an effect carbonic acid will have on my water.
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post #6 of 11 (permalink) Old 07-08-2020, 03:37 AM
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Originally Posted by Betta Splendid View Post
As for getting the proper PH/KH, is it the same as leaving my tap water out for a couple of days instead of aquarium water? I've checked my tap before and it was identical to the tank.
Not necessarily. You could be adding bicarbonates that would raise KH. A full list of what you dose would reveal this. Things in your tank (substrate, rocks, etc.) could be increasing KH as a function of pH changes and, lastly, BB will consume bicarbonates. So, it is best to identify your tanks' KH, then take a sample and let it sit out. When you measure your sample, a few days later, and compare the pH levels, be sure to test the tanks' KH level to be sure that it matches the KH that existed when you took the tank sample. The KH in my tank will drop throughout the week.

I run my CO2 24/7 and see no significant change in pH, night or day. There are some plants (CAM) that utilize CO2 in the dark (they don't all use O2 at night). So, I let CO2 run day and night to benefit my Dwarf Sag (a CAM plant) and to maintain pH at a stable level below 7.0 (I don't want to risk my ammonium turning into ammonia). I also have noted that running CO2 24/7 uses less total CO2 to maintain the same CO2 level. As soon as ambient light enters the room in the AM, plants can begin photosynthesis. Having said all of this, I've also run on a timer and see no large difference between the two in plant performance but, since I use less CO2 with 24/7 and the other issues, I see no reason to revert to timing the CO2 - nature doesn't do it.
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post #7 of 11 (permalink) Old 07-08-2020, 05:45 AM
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One thing I do in my tank at night I have two air stones at each end of the tank and I run them during the hours of darkness (the 12 hours my lights are off.) that works just fine for my plants and fish. I run an Emperor 400 and the old Marineland H.O.T. Magnum filter in the tank. The Magnum has an adjustable water diffuser which at night I rotate 180* so that the surface of the water is agitated during those 12 hours of darkness. If you monitor your pH at nights it should be a slight higher than during the day. But like I said the two air stones make a big difference and I have them hooked up to an air manifold with adjustable valves to control the flow. Each line has a one way check valve on the event of water being syphon into the lines when the air pressure subsided or in the event of a pump failure.

You can just see the air line with the stone on the corner of the tank.
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post #8 of 11 (permalink) Old 07-18-2020, 02:18 AM Thread Starter
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Quote:
Originally Posted by Deanna View Post
Not necessarily. You could be adding bicarbonates that would raise KH. A full list of what you dose would reveal this. Things in your tank (substrate, rocks, etc.) could be increasing KH as a function of pH changes and, lastly, BB will consume bicarbonates. So, it is best to identify your tanks' KH, then take a sample and let it sit out. When you measure your sample, a few days later, and compare the pH levels, be sure to test the tanks' KH level to be sure that it matches the KH that existed when you took the tank sample. The KH in my tank will drop throughout the week.

I run my CO2 24/7 and see no significant change in pH, night or day. There are some plants (CAM) that utilize CO2 in the dark (they don't all use O2 at night). So, I let CO2 run day and night to benefit my Dwarf Sag (a CAM plant) and to maintain pH at a stable level below 7.0 (I don't want to risk my ammonium turning into ammonia). I also have noted that running CO2 24/7 uses less total CO2 to maintain the same CO2 level. As soon as ambient light enters the room in the AM, plants can begin photosynthesis. Having said all of this, I've also run on a timer and see no large difference between the two in plant performance but, since I use less CO2 with 24/7 and the other issues, I see no reason to revert to timing the CO2 - nature doesn't do it.
Apologies for the delay, Deanna. Thank's for the input. I didn't know some plants consume co2 at night! Would be nice for me if the dwarf sag grew slower, it's sending out runners all over the place hahaha.

So I did the Ph/Kh comparison and there was no difference. Aged tank water Kh remained the same. Now, the Ph is slightly lower than I thought. I've started using the brightest area in the house near a large window to read the results and there is a difference compared to the spot I used to use. So it's about 7.4, not 7.6. I've been off on all my api tests by a bit for years before this new spot.

I've set the co2 at 1 bps and ph drops to about 7.0. So I'm at 15ppm according to the chart. I'm very happy with how things are going. The plants are growing fuller and bigger. Also noticing quite an increase in nutrient uptake so I'm now dosing PPS Pro along with modified EI because I do 10% weekly w/c.

At the moment I'm dosing:

-API Leaf Zone for daily PPS level K and Fe
-Tropica Premium for daily traces (one squirt, K and Fe very low on this)
-Seachem Flourish Potassium (a little added to new water on w/c to have a base level of 20ppm)
-Seachem Flourish Phosphorus. I don't dose this much because my tap water contains 1ppm already. I dose it to bring my level up to 3 or 4ppm and just leave it, testing weekly. When it drops to around 2, I dose again.
-Seachem Flourish Nitrogen. Same way as P. I dose this to bring nitrates up to the high 30's. Whenever it falls below 20, I dose again.

I have many unopened bottles of these liquid ferts. When I run out I will probably order dry ferts from GLA.

I'm okay with the co2 being off at night because the difference for me is only a 0.4 swing in ph.
I thought I'm saving co2 with it off at night? My bubble rate is a constant 1 bps and doesn't change. Are you using a controller for your co2? I'm trying to figure out how you use less co2 running it 24/7. I only know the basics for pressurized equipments.
Can you write a simple explanation so I can understand it better?

Thanks again

Quote:
Originally Posted by Backblast72 View Post
One thing I do in my tank at night I have two air stones at each end of the tank and I run them during the hours of darkness (the 12 hours my lights are off.) that works just fine for my plants and fish. I run an Emperor 400 and the old Marineland H.O.T. Magnum filter in the tank. The Magnum has an adjustable water diffuser which at night I rotate 180* so that the surface of the water is agitated during those 12 hours of darkness. If you monitor your pH at nights it should be a slight higher than during the day. But like I said the two air stones make a big difference and I have them hooked up to an air manifold with adjustable valves to control the flow. Each line has a one way check valve on the event of water being syphon into the lines when the air pressure subsided or in the event of a pump failure.

You can just see the air line with the stone on the corner of the tank.
That's tank looks super! I love tanks with large swords. Is it the camera or is your lighting fairly dim? I've always liked dim lighting and prefer it 99% of the time.

Yup, my Ph goes up at night. For me it's a 0.4 swing. Are you running your co2 24/7?
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post #9 of 11 (permalink) Old 07-18-2020, 02:27 PM
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Originally Posted by Betta Splendid View Post
I'm okay with the co2 being off at night because the difference for me is only a 0.4 swing in ph.
I thought I'm saving co2 with it off at night? My bubble rate is a constant 1 bps and doesn't change. Are you using a controller for your co2? I'm trying to figure out how you use less co2 running it 24/7. I only know the basics for pressurized equipments.
Can you write a simple explanation so I can understand it better?
Very glad to hear that your tank is now where you want it to be.

No, I don't use a controller, just an open solenoid. A simple explanation for less CO2 consumption when running 24/7? I'm not sure I'm capable of doing that, but maybe this will work:

It is recommended that heat pumps (of which I am cursed of having) be run with very little changing of the thermostat night and day. Maintaining a consistent temperature, as opposed to letting it drop 10 degrees at night while sleeping, uses far less electricity than trying to bring it back up in the morning. Pushing CO2 into saturation is similar and, I believe, is the main reason that I make fewer trips to the CO2 store when running 24/7.

Less simple reasons:

There are subtle issues that, I believe, are also helped and it is all mainly about maintaining stable parameters. These are beliefs that I have based upon many things.
- preventing ph from rising above 7, as it would at night in my case, prevents possible additional stress on my fish due to NH4 changing to NH3.
- algae love unstable CO2, especially BBA (water changes are a little scary, but I do them because the benefits outweigh the risks and I do them during the siesta). If my pH moves half a point twice a day, that’s about a 20ppm move.
- conversely, plants don’t like unstable CO2 and, therefore, may be slightly weakened.
- nutrient uptake is optimal in the mid 6’s, pH wise.
- chelated minerals may oxidize and precipitate out, making them unavailable to plants during the day.

So, if all of our plants (including C4-type plants that have accumulated CO2 at night) and algae begin photosynthesis as soon as ambient light from the room reaches them, which has been shown, I should have to start the CO2 up at around 4-5AM. This leaves little time for CO2 being off to make much difference.

Having said all of the above, I've run it both ways and, although my tank is nearly perfect (to me), now vs. years ago when I shut it off at night, I can't say that it is due only, or even largely, to runnig CO2 24/7. Running 24/7 just to save a couple dollars a year on CO2 is not the reason that I do it. It is just a side observation.
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post #10 of 11 (permalink) Old 07-19-2020, 07:01 AM Thread Starter
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Quote:
Originally Posted by Deanna View Post
Very glad to hear that your tank is now where you want it to be.

No, I don't use a controller, just an open solenoid. A simple explanation for less CO2 consumption when running 24/7? I'm not sure I'm capable of doing that, but maybe this will work:

It is recommended that heat pumps (of which I am cursed of having) be run with very little changing of the thermostat night and day. Maintaining a consistent temperature, as opposed to letting it drop 10 degrees at night while sleeping, uses far less electricity than trying to bring it back up in the morning. Pushing CO2 into saturation is similar and, I believe, is the main reason that I make fewer trips to the CO2 store when running 24/7.

Less simple reasons:

There are subtle issues that, I believe, are also helped and it is all mainly about maintaining stable parameters. These are beliefs that I have based upon many things.
- preventing ph from rising above 7, as it would at night in my case, prevents possible additional stress on my fish due to NH4 changing to NH3.
- algae love unstable CO2, especially BBA (water changes are a little scary, but I do them because the benefits outweigh the risks and I do them during the siesta). If my pH moves half a point twice a day, that’s about a 20ppm move.
- conversely, plants don’t like unstable CO2 and, therefore, may be slightly weakened.
- nutrient uptake is optimal in the mid 6’s, pH wise.
- chelated minerals may oxidize and precipitate out, making them unavailable to plants during the day.

So, if all of our plants (including C4-type plants that have accumulated CO2 at night) and algae begin photosynthesis as soon as ambient light from the room reaches them, which has been shown, I should have to start the CO2 up at around 4-5AM. This leaves little time for CO2 being off to make much difference.

Having said all of the above, I've run it both ways and, although my tank is nearly perfect (to me), now vs. years ago when I shut it off at night, I can't say that it is due only, or even largely, to runnig CO2 24/7. Running 24/7 just to save a couple dollars a year on CO2 is not the reason that I do it. It is just a side observation.
Thank you for the explanation, Deanna. I'm thinking about giving your method a try on a 20 gal with a 15w T8 I plan to set up in the near future. A 20 gal low light shouldn't require much co2 to keep a decent level 24/7, so I'm fine with that.
You just saved me money as well because running co2 24/7, I can go with a single stage regulator for the new tank. Thanks again!
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post #11 of 11 (permalink) Old 07-19-2020, 01:22 PM
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I'm thinking about giving your method a try
Many of us run 24/7.
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