Pressurized CO2 Reactor

[tsonnenl]

I'm getting nearer to setting up a pressurized CO2 system for my 72g planted, but I was hoping not to have any more equipment taking up space in the tank, be it an in-tank reactor or a second powerhead to run an external reactor. I've looked over the products for sale on aquatic-store.com and looked extensively at the links Mr Burns listed in a recent post (thank you, VERY helpful time saver) and it seems like this might not be possible. Here are the options I am currently mulling over.

1) I had read that some people plumb the CO2 into the intake of their canister filter so that the bubbles have time to dissolve as they fight against the current.

Concerns:
-Wouldn't the current of an Eheim 2026 be more than strong enough to pull the bubbles against gravity and into the filter, making the "fight against the current" non-existent?

-Would pumping CO2 into the intake make the fabled carbonic acid eat at the internals of my filter? If so, why would this be any different than pumping CO2 rich water through the filter after using a real reactor?

2) I have also read that some people plumb the CO2 into the exhaust of the filter.

Concerns:
-Going with the current in the exhaust, the CO2 would only be in the tube for a second at most before being spewed out just below surface level in the tank. That seems like a shorter time than if it was just released at the bottom of the tank and allowed to naturally rise to the surface, right?

3) I do have that first powerhead in the tank that could be used if needed.

Concerns:
-I get the impression that releasing CO2 directly under the intake of a powerhead is an extremely inefficient way of getting it dissolved, and I wouldn't really want to see any chopped up bubbles coming from it either.

4) Suck it up. Get a reactor to sit in your tank and look at the other corner if you have to.

What do you think? I really don't want anything more than a small tube visible if I can help it.

Thanks in advance.
Todd

 

[Mr Burns]

the best way to do a reactor is to put it in-line with your filter return line. as for your concerns over that, the proper reactor design will alleviate that problem. rex has a very good reactor design in his FAQ, but the best i have seen so far is http://www.hoftiezer.net/personal/aquaria/aquaria_construction_co2reactor.htm . That's the one i'll be building. as for the rise time...if you the co2 is properly dissolved in a well-designed reactor, this won't be a concern...in fact, many people that have built the reactor linked to above say the bubbles dissolve completely before they even get to the bio-balls.

no tube needed inside the tank except from the filter return line. hth

 

[tsonnenl]

Hmm, that's more like it. I see the professionaly made one is for aquariums up to 500 gallons....that's a little excessive. I might look for a smaller version of that and happily eat the 30-40 bucks and not end up with water all over my walls when I screw up the DIY. You'd think I'd be more daring after my success with making a canopy for my AHsupply kit.

I'm VERY interested in hearing how your construction goes. Do you have a time frame for when you're going to dive into it?

 

[Mr Burns]

i have a paper for a research class due on thursday. that is going to be the biggest obstacle in constructing the reactor, but i might pick up the parts for it tomorrow afternoon after my last exam. if nothing else is going on, i'll build it on thursday or over the weekend since my JBJ regulator from aquabotanic arrived today and i want to get my new filter up and running in my current 29gal. you should be able to build the reactor in the link i gave you for less than $25. i figure a lot of those little parts are maybe 25¢ each, and there's not many parts. if you or a friend already have some extra bio-balls and pvc primer/cement, you're half way there!

about the return line on your tank - you pretty much keep it the same, except cut it in half and hook up the reactor accordingly. no fuss, no muss, and no extra pipes or equipment inside the tank.

 

[Mr Burns]

tsonnenl, i bought all my parts today. i followed the hoftiezer reactor plans pretty closely. i modified the bottom so that it is at a right angle coming AND going out. the way it was before, the hose coming out of the bottom of the reactor would have had to be really bent around to go back up into the tank. i made one other modification....i am using brass adapters for the barbs. does anybody know if these are ok to use?

 

[Mr Burns]

brass isn't good b/c of the copper thing, so i searched around and found the proper plastic adapters. i'm keeping the CO2 inlet adapter brass simply as a safety precaution. the inside of the fitting is large enough that i can put a thin layer of silicone so that the brass isn't completely exposed. it is a locking fitting, similar to the fitting on needle valves.

the clear pvc was going to be stupid expensive b/c it has to be ordered in 10ft lengths, and i only need one foot. i'll just have to check inside every couple months and make sure there is nothing building up, although i don't see why anything would since prefiltered water is the only thing going though...

i have it all dry-fitted together right now, so here's a few pictures. please excuse the horrible resolution..

the first is just an overview of how the inlet and outlet are angled so that i don't have the filter hoses bent at really bad angles. the second will be the bottom/outlet of the reactor and the third is the top/inlet. the fourth picture is a bad close-up of the co2 inlet fitting...the line fits down over the center piece, set into the top of the piece on the left, then the bolt/collar on the right slips over and locks the tubing into place. i may add a check valve to this, but it depends on if i can find one that will operate under such low co2 pressure...

 

[Mr Burns]

d'oh...the pictures are backwards and i forgot to add the brass fitting...

 

[tsonnenl]

I found clear PVC at savco.com in 5ft lengths. $5.63 isn't bad. Its a #4 at Wendys...

Wanna make me one with your extra parts? Have you ever seen the movie Contact?

"Why make one when you can make two for twice as much?"

 

[tsonnenl]

Uh, that's 5 per foot, then 7 bucks shipping - 32 total. Right...

 

[Mr Burns]

yeah, 32 is excessive... especially when i can build the entire thing with out it for around $25. that price is even less now because the primer and cement were the most expensive items. the clear pvc is just a convenience and makes the project look more professional, it adds nothing to the functionality. maybe once every few months i'll go through the trouble of checking to make sure the bio-balls aren't gunked up, or there's nothing obstructing the flow...that's what the test tee with the threaded cap is for. i really don't think it will get dirty though..it's all prefiltered water....

 

[Mr Burns]

ok, tsonnenl, construction is complete. easy easy.

total assembly time (with no prior pvc experience) was about a half hour. that includes cutting the 1" pvc sections to join the top and bottom elbows. i would have had it completed on sunday, but in my haste i glued some small pieces together that weren't meant to be glued together. it will be much easier building the next one now that i know where all the parts are... i can't really give you a total cost because in my inexperience, i made a lot of mistakes and quick decisions...live and learn! i think total cost now would be around $20 because i know exactly what to get, where, how to put it together exactly, and i already have the primer and cement...

seriously, i would build one for you...but times being as f'ed up and irrational as they are, i'd probably get labelled a terrorist for mailing a big pvc thing through the mail.

 

[geoffs]

So, Mr. Burns, nice job on that DIY reactor. I've just gotten most of the parts for building the same one, but my darn local Home Depot didn't have:

1. The 2" cleanout tee
2. Correct size hose barbs to NPT 3/4" and 1/2" thread
3. 2" pvc pipe in white or black - grrrr

Was it at your own local HD where you bought the stuff? ...or where...

Thanks,
Geoff

 

[Mr Burns]

my 5/8 to 1/2 barbs for the inlet and outlet lines were hard to find, not sure about the 3/4" barb to 1/2"npt. they were in these pull-put trays in the vinyl tubing section of HD. it took me about 20 minutes to find them because they were on a lower shelf, and behind a box of odds and ends. the 2" x 2" x 2"npt tee and 2"npt plug were the first things i found at home depot, the rest i had to hunt around the pvc aisle for. i got my 2" pipe from a local store down the road that cuts it to length, thus saving a lot of money and hassle.

i just realized i should have taken an exploded picture of the parts to better explain what i used, but it's a little too late. i was unable to find the 2" x 1" reduction bushing, so i had to step it down - 2" x 1.5" reduction fitting (looks just like a little circle of plastic) to a 1.5" x 1" reduction bushing.

 

[tsonnenl]

HAHA, you're probably right about that looking like a pipe bomb by an uninformed postal inspector! I never thought of that. There's a guy over on plantedtank.net trying to get people together like a group buy to have him to buy parts in bulk and send them out assembled to people. He might have the FBI at his door next week.

I'm curious to hear how the reactor wtih two elbows instead of one affected your flow rate. I know you can't compare between one elbow and two, but is the flow rate noticably less?

I'm getting closer to talking myself into this. I really want that clear PVC though... :?

 

[Mr Burns]

i don't see any reason why that extra elbow at the bottom would change the flow rate... the entire tube/assembly will be filled with water being pushed through by the filter motor, and the bioballs shouldn't be too much of an obstacle. i supposed i could take this stuff down to the washroom and figure it out, but...eh, that's just too much work

 

[tsonnenl]

Have you hooked it up to your canister yet? You might be surprised.

Any change in direction in the tubing should result in turbulence in the water, slowing down the flow rate, just like the air through intake on your car. Straight is fast.

That said, I hope you're right. That extra elbow would be helpful in keeping the inside of the stand cleaner looking, without tubing looped all over the place.

 

[Mr Burns]

i don't have the new tank even built yet, so i don't want to get everything out to test the flow yet... but my guess is that since the water is being pushed through, an angle at the top some bioballs, and an angle at the bottom shouldn't make much of a difference. likewise, i'm going from a filter hose with an internal diameter of 5/8" to pipes/fittings that are no less than 3/4". the increased diameter should alleviate any flow restrictions.

i still think the fact that water is being being pushed, and not pulled, through makes the difference minor...

maybe i'm wrong...i'm just taking educated guesses here. i can always redo it if the flow is reduced too much, but i doubt that is going to be the case.

 

[Mr Burns]

well, i talked with james hoftiezer (the guy that made the reactor plans) and he said that the extra elbow will reduce flow, but not much. it shouldn't affect much overall. he went on to say that even with a reactor and UV unit in-line with his filter, he didn't notice much of a difference...