DIY CO2 nightly shutoff - The Planted Tank Forum
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post #1 of 27 (permalink) Old 01-05-2016, 03:30 AM Thread Starter
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DIY CO2 nightly shutoff

Has anyone setup your DIY CO2 to shutoff at night? It would require two things: a pressure release valve so your 2l bottles don't over pressurize and explode, and some sort of electric valve you can plug into a timer. Would love to hear your suggestions, especially if you've successfully done this.
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post #2 of 27 (permalink) Old 01-05-2016, 03:36 AM
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Nope. The CO2 flow is so low that all night long is just enough for there to be plenty of CO2 in the water for the plants when the lights come on.

Low tech on/off (sort of):
Put the yeast on top of the tank light. It will run a bit faster as the light warms up, then slow down when the light goes off and cools down.
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post #3 of 27 (permalink) Old 01-05-2016, 03:42 AM Thread Starter
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Originally Posted by Diana View Post
Low tech on/off (sort of):
Put the yeast on top of the tank light. It will run a bit faster as the light warms up, then slow down when the light goes off and cools down.
Lol. Maybe I'll just put the bottles on a heat pad.
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post #4 of 27 (permalink) Old 01-05-2016, 03:58 AM
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Well, then you could time it so the CO2 starts earlier than the lights, to boost the levels some before the lights come on.
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post #5 of 27 (permalink) Old 01-05-2016, 04:29 AM Thread Starter
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Well, then you could time it so the CO2 starts earlier than the lights, to boost the levels some before the lights come on.
A timer valve + pressure release valve can also accomplish that. The timer valve stops the CO2 at night. The pressure release valve allows for some additional build up of pressure, but not so much that it blows a line. When the timer opens the valve in the morning, you get a big push of CO2 into the reactor. The more air space you have in your CO2 bottles, the more CO2 will be stored up and pushed out in the morning. You could even add empty jugs just for the purpose of storing more CO2 overnight.

And to take it a step further, after the big CO2 release in the morning, close the timer valve again. Wait a couple of hours and then open it. No sense pushing out CO2 while it's still clearing out the CO2 from the big burst you got.
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post #6 of 27 (permalink) Old 01-05-2016, 06:11 PM
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Originally Posted by cjp999 View Post
Lol. Maybe I'll just put the bottles on a heat pad.
A variation on this idea will work very well. You can put the bottles in a tub of water, with a timer controlled heater, but this will react very slowly due to heat storage in the water. You could wrap a heating pad around each bottle, but the temperature of the heating pad would have to be lower than most heating pads will go. You could use a two tub water bath, with a small water pump to pump the warmed water into another tub for overnight, and back during the lights on time.

The amount of CO2 usually generated by a DIY system is so low it does no harm to keep it on 24 hours a day, and this "method" doesn't cost anything to set up.

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post #7 of 27 (permalink) Old 01-05-2016, 07:06 PM Thread Starter
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The amount of CO2 usually generated by a DIY system is so low it does no harm to keep it on 24 hours a day, and this "method" doesn't cost anything to set up.
I run 4x 2l bottles on my 46g, swapping out 1 per week. My pH is normally quite high (with no CO2 added). About 8.4. It's measuring around 7.6 in the DIY CO2 tank right now. I think this equates to something around 10ppm.

I dug up some old posts I did 5 years ago when I was rotating in a fresh bottle a bit more frequently (I did 3 in 2 weeks) and the pH had dropped to 6.5. That was 80ppm! However, I think maybe I just had a couple of really hot bottles at the time. I then cut back a bit on the new CO2 bottles and started to use a drop checker, and was pretty consistently up in the 20-30ppm range.

However, I had trouble keeping fish healthy. It's so hard to get consistent CO2 output from DIY, and trying to push into the 20-30ppm range without going well over at times is near impossible. So I cut back even more, and now swap in 1 fresh bottle per week. I've been doing that for 4 years (when I keep up with it), and haven't bothered trying to calculate CO2ppm since then until today.

I think preventing or limiting production at night, and getting a boost during the day would make it easier and safer to try to push higher numbers.
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post #8 of 27 (permalink) Old 01-05-2016, 09:59 PM
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A 0.8 drop in pH due to adding CO2 means you may have around 20 ppm of CO2. But, as you noticed, it is very hard to keep the concentration of CO2 consistent day to day with DIY CO2. Also, I don't know how much light you have, so I can't guess if that is enough, or too little CO2. The more light intensity the more CO2 is needed to keep up with the plant growth rates.

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post #9 of 27 (permalink) Old 01-05-2016, 10:33 PM Thread Starter
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Originally Posted by Hoppy View Post
A 0.8 drop in pH due to adding CO2 means you may have around 20 ppm of CO2. But, as you noticed, it is very hard to keep the concentration of CO2 consistent day to day with DIY CO2. Also, I don't know how much light you have, so I can't guess if that is enough, or too little CO2. The more light intensity the more CO2 is needed to keep up with the plant growth rates.
78w t5h0. 3" above the lid.
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post #10 of 27 (permalink) Old 01-06-2016, 03:54 AM
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Who makes that light fixture? Some T5HO lights have good reflectors and fully powered ballasts. Others don't.

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post #11 of 27 (permalink) Old 01-06-2016, 04:04 AM Thread Starter
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post #12 of 27 (permalink) Old 01-06-2016, 04:16 AM
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Another way to get an AM burst is to swirl the bottle when you feed the fish in the AM. Unfortunately this is such a large sudden burst that it mostly rises through the water and escapes. Need a better diffuser, able to handle this larger volume of CO2.
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post #13 of 27 (permalink) Old 01-06-2016, 09:31 AM
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Hi guys, check this out. I think this should be a more pro technology for DIY CO2 system.


https://youtu.be/hQ9nfWXZZ-s

Sent from my SM-N910G using Tapatalk
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post #14 of 27 (permalink) Old 02-26-2016, 05:05 PM
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Quote:
Originally Posted by Diana View Post
Nope. The CO2 flow is so low that all night long is just enough for there to be plenty of CO2 in the water for the plants when the lights come on.
The idea that DIY Co2 is too ineffective to be able over supply Co2 is commonly seen in discussions on the topic, and is one I took at face value until I began regular testing of the KH & GH of the water in my 90g and calculating the Co2 ppm. This morning, prior to lights on, the level is 42ppm (PH 6.7, KH 7), a little high based on the recommendations I've read here and elsewhere. The fish are showing no signs of distress though.

A single 1g glass container with the often recommended recipe of 2 cups sugar, 1tsp yeast and 1tsp baking soda. Silicon hose with a check valve to a wooden block diffuser. Runs 2 to 3 weeks. I change it when the output visibly slows down, and the new batch is producing in 20 to 30 minutes.
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post #15 of 27 (permalink) Old 02-26-2016, 05:20 PM Thread Starter
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Originally Posted by Westone View Post
The idea that DIY Co2 is too ineffective to be able over supply Co2 is commonly seen in discussions on the topic, and is one I took at face value until I began regular testing of the KH & GH of the water in my 90g and calculating the Co2 ppm. This morning, prior to lights on, the level is 42ppm (PH 6.7, KH 7), a little high based on the recommendations I've read here and elsewhere. The fish are showing no signs of distress though.

A single 1g glass container with the often recommended recipe of 2 cups sugar, 1tsp yeast and 1tsp baking soda. Silicon hose with a check valve to a wooden block diffuser. Runs 2 to 3 weeks. I change it when the output visibly slows down, and the new batch is producing in 20 to 30 minutes.
Wow, that's impressive for 2 cups. I run 4 2l bottles (2 cups sugar each), rotating a new bottle in each week, so each bottle runs for 4 weeks. Helps keep the CO2 levels a bit more consistent that way. This is on a 46g. A couple months ago I started using a drop checker again (I stopped 5 years ago), and it was consistently green.

However, last week when I got back from a week long vacation the drop checker was blue (I had rotated in a new bottle the day I left). I rotated in another new bottle (this was just part of the normal scheduled rotation) and it's still been nearly blue the past week. I'm not too sure what's going on. I still see pearling. Perhaps increased plant growth is leaching a lot of CO2. I did a replant 2 months ago, so plant mass was a lot lower when I first started using the drop checker. I've always wondered how many ppm of CO2 a well planted tank can consume. Would you expect it to produce a noticeable dip in CO2 levels?
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