# Running a co2 system without solenoid valve



## SudhirR (Apr 7, 2020)

Hi all,

I am getting a diy co2 system from a friend. This is a bicarbonate and citric acid based reactor - diy system. The kit comes with a single stage regulator, needle valve, bubble counter and ceramic diffuser. 

Wanted to know if I can run this system on 24x7 without a solenoid kit. I do not have any exp with pressurised co2 systems in the past. 

The tank is a 30 cm cube tank, heavily planted with medium to high light 45W WRGB system from Chihiros. Stocking is just ember tetras and tiger shrimps. 

pH stays at around 7.25 and I want to drop this to around 6.8 with co2 injection. Pls suggest your thoughts. 


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## mistergreen (Mar 3, 2007)

In a diy system, you don’t need a solenoid. It would be good to have an air stone turn on when the light turns off to give fish O2 and degas the co2. Have the air stone turn off an hour defore the lights turn on.


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## SudhirR (Apr 7, 2020)

Thanks. I will run the air stone for lights off hours. 


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## SudhirR (Apr 7, 2020)

Works great. Thanks for your suggestions. My Kh is 2 dKH. I am running this DIY reactor with about 1 bubble per 3 seconds. Around 19-20 bubbles per min. 

I aerate in the night once the lights go off. I switch off aeration about 3-4 hours prior to photo period and pH shows about 6.8 at the moment the aeration if switched off. 

By the time the lights switch on (which is a good 3-4 hours) the CO2 builds up to make a pH of 6.6. So that’s a CO2 of about 19-20 ppm on the charts. 

During photo period the pH marginally increase to 6.7 to around 6.75 at the time of lights off. Since my water is soft at 2 dKH if I inject more CO2 to achieve optimal levels of 30 ppm, I feel the pH would start swinging between 6.3 and 6.8 which would stress out the fish and shrimps. 

Any suggestions? 


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## mistergreen (Mar 3, 2007)

pH swings from CO2 is not a problem. You can increase the dKH to 4-6 and gH for the plants to get their Ca & Mg nutrients.


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## hoppycalif (Apr 7, 2005)

One bubble every 3 seconds is very little CO2. And, the charts of CO2 vs KH and pH are not correct for typical aquarium water, only for pure water with nothing in it except carbonates and CO2. Try checking tank pH after a few hours of no CO2 being added, and after a few hours with CO2 added. The ppm of CO2 will be about equal to 3 times 10 raised to the drop in pH power. For example: if the pH with no CO2 is 7.0 and with pH is 6.6, the amount of CO2 is about 3 times 10 to the 0.4 power, which is about 8 ppm. For 30 ppm of CO2 the 7.0 pH would drop to about 6.0 pH.


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## AlyssaKayM (Aug 14, 2020)

I just dug up this very diy co2 set up that I bought a few years ago - but lost the instructions that came with it. the bottles that came with the system are not 2 liter bottles though - they are 1 liter bottles.

So not sure really what the mixtures should be for each bottle.

And I keep finding references to being careful about the pressure - like whats the worst thing that can happen? The bottles burst and spray citric acid everywhere?

I'm wanting to use this in a 5 gallon tank that only has plants - no fauna - so I don't have to worry about it dumping or anything right now.


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