CO2 Setup

[tomterp80]

Honeslty with the Eheim filter you could just feed the CO2 into the intake tube and skip the reactor build altogether. The impeller in the filter will break up the CO2 sufficiently enough.

Hello folks.

Has anybody experimented with bubbling CO2 into a filter pad, where presumably the bubbles would attach and absorb as the water flows past?

I have a large foam cannister filter element within my 75g, it's nearly as tall as the tank itself and resides in a partitioned section of the tank. I have not experimented with this idea, partly because I can't see into the depths of the compartment where the bubbles would be emitted. A power head resides atop the filter pad, drawing water through the pad and out the top back into the tank. Water is drawn into the pad from all around the side of the pad.

At present I am using an Eheim diffuser (CO2 pushed at pressure through a ceramic plate) and probably lose about 50% of the CO2. Though I am getting enough absorption to lower my pH to 6.8 from 7.6, the system is inefficient and I would improve it if it were practical. I am counting about 2 bubbles per second at present.

Any thoughts?

[Aaron]

I've never seen such a filter system before. If the CO2 system you have is working well enough to bring the pH to a desirable level at 2 bubbles / second I would say that's pretty efficient for a 75 gallon tank. One way to save a lot of CO2 is to use a solenoid to shut it off at night while the plants and fish are sleeping.

[tomterp80]

I purchased my tank in Texas, it's a DAS (Dutch Aquatic Systems). Very nice exterior pickled oak trim, flatback hex design. There are three chambers in the back left corner of the tank, one for the filter element, one for the heater, and a third for any supplemental filtering or whatever.

Each compartment runs the full distance from top to bottom, with slots in between to allow the water to pass through the compartments in sequence. You get a constant flow of water around the heater, which works great. Also, when I clean the filter element about every 6 months, it's impressive how little remains to be cleaned, it's a good bio filter.

But back to your suggestion: My CO2 is a high pressure system. That is, there is a regulator, but no needle valve. The CO2 is pushed under about 18lbs pressure to the Eheim reactor, which requires pressure to force the gas through the ceramic plate. A few streams of tiny bubbles stream out continuously, rise up and then are knocked down again by the filter outflow. By the time they reach the surface, they're pretty small.

Can a solenoid be used in such a setup? I am not familiar with their mechanics of these devices. I will say that sometimes my fish are stressed in the morning, gulping oxygen on top due to the excess CO2 probably. (I've never taken a pH reading in the morning, probably don't want to ) So I am interested if it's feasible.

[Aaron]

Do you have a picture of the type of regulator you are using? I would imagine that it's possible to put both a solenoid and a needle valve on there.

[tomterp80]

I will take some pictures probably tomorrow.

I don't really need/want a needle valve. The Eheim reactor requires high pressure, the needle valve is really meant to reduce pressure for the precision systems most folks are using, is the way I understand it. I.e, releasing one bubble per second into some diffuser apparatus. The Eheim requires high (18-20 psi) to force CO2 through the ceramic disk. Just the standard regulator is all that is required, no step down via a needle valve.

When I got into this plant tank keeping, I was living in Dallas and had no peer group to consult, and I learned about the Eheim system via the Krib website. I think it works fine with the exception that nobody else is doing it, hence a lack of ability to consult with somebody else with the same hardware.

Is anybody else using an Eheim ceramic disk reactor to diffuse CO2? I don't even know if they're sold anymore.

[Aaron]

I think krisw is using one. You can still use a needle valve on those ceramic discs. Because your tank is so large you are not having problems, but someone with a smaller tank might with that setup. The pressure inside the tubing would still build up enough to push through the disc.

Anyhow, a solenoid to turn things off at night sounds like it would suffice and save you some CO2 in the process.

[tomterp80]

Anyhow, a solenoid to turn things off at night sounds like it would suffice and save you some CO2 in the process.

I'm interested in doing this. I know the fish are stressed in the mornings sometimes, particularly when the plant biomass is at its occasional peaks.

I'm going to take some pictures today and see if I can load them successfully (not a given with my technical skills!)

[krisw]

I think krisw is using one

Nope. I'm using one of Ghazanfar's design in-line CO2 reactors with my Eheim. In my other tank, I'm using a Dupla in-tank reactor, but it's not ceramic based. I intend to get rid of that, and move to an in-line design in the next few months.

Eitherway, looking forward to your pictures tomterp80.

[tomterp80]

I put a few pictures out in the Gallery under a new thread. Certainly makes things easier to explain, hopefully.

[tomterp80]

Ok, hopefully you guys have seen my CO2 setup, and can advise me on a reasonably expeditious way to have the CO2 shut off when the lights time out.

I presume it would have to be something in-line between the regulator and diffuser. Thoughts?