[auban]

many people have told me that DIY CO2 is ineffective on a tank larger than about 30 gallons or so. when i disagree with them, it usually starts an argument... anyway, i have not been monitoring the actual CO2 levels in the tank and instead have just been watching the fish every time i recharge a bottle or add another one. right now, i can only run two bottles on my 55 gallon tank. three will kill fish and shrimp. i have ordered a drop checker so ill start getting some actual readings soon. according to the ph/kh calculation, my CO2 was just over 60ppm when i took this video.

in this video, i am showing you my basic setup. the lines run from a one gallon juice bottle into a 20oz coke bottle that is connected to a maxijet 400. at the end of the line, inside the 20oz, i added a small ceramic disk type atomizer that was marketed for nano tanks. i have two of these, one on each side. right now, one of the bottles is a two liter coke bottle.

the bottles that i use are not the reason i was able to gas the fish. its the ceramic disk atomizers that feed into maxijet 400s that make this DIY CO2 setup dangerous. the tetras started showing signs of being gassed before i was able to bring the CO2 levels down.

none of my fish died from this event. i was able to pull the CO2 and save the fish. i slowly reintroduced the CO2(aimed the maxijets at the surface) and now the fish are doing fine with both bottles running and both maxijets aimed down across the tank for maximum diffusion.

http://s1242.photobucket.com/albums/gg522/sjveck/?action=view&current=20121215_132637.mp4

 

[aznartist34]

I think your problem is surface agitation. There's not enough oxygen in your tank. There doesn't seem to be much flow in your tank so your co2 isn't dissipating out of the water. Generally a planted tank would benefit with some more flow.

 

[auban]

probably so, but two maxijet 400s and one marineland c-220 werent enough to keep from gassing the fish.

on another tank i use a maxijet 600 which blows across the surface of the tank in a circular pattern. i keep one 3 quart yeast bottle on the tank(65g). for a the last few months i didnt run any CO2 in it and you can tell buy looking at my snails.

you can see when i stopped using the one bottle of CO2 by the corrosion:

i didnt gas the fish with just one bottle on the larger tank, but it had a noticeable effect.

 

[DarkCobra]

Ineffective, no. Can easily be done with either a brute force or highly efficient setup. More costly over time and labor intensive than many prefer, yes.

Insufficient oxygen? Possibly. But can be blamed when it's not the case, since we have no way to measure O2 levels. Increasing flow and surface agitation may appear to solve the O2 problem, but as it drives off CO2 as well, which dissolved gas was really responsible?

In my experience, increasing CO2 from 30ppm (or less) to 60ppm in less than a day's time can severely stress fish that have not been acclimated to such high levels in the recent past. I suspect this is what you're seeing. If the increase is done over a week's time, the same fish in the same tank will happily tolerate even 80ppm.

 

[auban]

Ineffective, no. Can easily be done with either a brute force or highly efficient setup. More costly over time and labor intensive than many prefer, yes.

Insufficient oxygen? Possibly. But can be blamed when it's not the case, since we have no way to measure O2 levels. Increasing flow and surface agitation may appear to solve the O2 problem, but as it drives off CO2 as well, which dissolved gas was really responsible?

In my experience, increasing CO2 from 30ppm (or less) to 60ppm in less than a day's time can severely stress fish that have not been acclimated to such high levels in the recent past. I suspect this is what you're seeing. If the increase is done over a week's time, the same fish in the same tank will happily tolerate even 80ppm.

i think you just hit the nail on the head. most people tell me that it is completely impossible to gas fish two DIY bottles on a larger tank like a 55g.

i agree that it is more expensive in the long run, but so far it only costs me about 8 dollars a month. when taxes come in ill probably go for a pressurized system. when i do, im going to use the same method of diffusion since i know it works so well. if i can do this with DIY CO2, i should have no problem working with a pressurized system. by the time the already fine bubbles get chopped up and spit out of the maxijet, they are so fine that they get blown all over the tank. there is always tiny bubbles everywhere. if you think about it, most people with DIY CO2 use horribly inefficient ways to deliver their CO2 to their tanks. i believe that is the biggest reason why i caught so much flak on another forum when i said i had DIY on a 55g.

a simple atomizer or air stone set at the bottom of the tank doesnt compare to what this configuration does.

i am looking forward to getting a pressurized system though. its a lot less dangerous once you start getting really efficient with diffusion. my yeast bottles randomly spike output for no reason. hard to control.

 

[HD Blazingwolf]

i saw no surface agitation in that video, and is the primary culprit for stressed fish. i inject about 7 bubbles per second into my 29 gallon. if not more and my fish are fine, spawning even. my 5 lb tank lasts about 3 weeks. Orlando and i have confirmed the regulator nor the tank have a leak anywhere. so im using this co2.

 

[auban]

surface agitation is the reason I actually prefer the maxijet 600 over the 400. it is able to push water across the top and back into the tank, so there is a decent gas exchange while at the same time forcing the fine CO2 mist into the lower levels of the tank. I have used it before with over driven bottles that burn themselves out in three days without issue. the maxijet 600 is quickly becoming my favorite piece of equipment, its just so darn versatile.

 

[HD Blazingwolf]

surface agitation is the reason I actually prefer the maxijet 600 over the 400. it is able to push water across the top and back into the tank, so there is a decent gas exchange while at the same time forcing the fine CO2 mist into the lower levels of the tank. I have used it before with over driven bottles that burn themselves out in three days without issue. the maxijet 600 is quickly becoming my favorite piece of equipment, its just so darn versatile.

you might soon learn to love a koralia
they are also awesome water moving pieces of equipment for their price

 

[auban]

i dont think a coralia would work well for a diffuser, but it would be perfect for increasing the surface movement in my 55g. it will probably also help push the CO2 deeper into the tank.

i may still stick with the maxijets though, since i can get them at around wholesale prices. less than twenty bucks for a 400, about 25 for a 600.

 

[kwheeler91]

i gassed some fish with two 2 liters on a 55 using the venturi on a ac50. it can definitely be done.