# DIY co2, few questions



## flashbang009 (Aug 6, 2009)

Ok. I think i've decided to start doing diy CO2 on my 75 gallon. I know some people might think its ridiculous to do it on a 75 but im gonna try. I have plenty of sites on setups and plans, so i just have a few questions regarding the kh, ph, etc.

My main concern is that when i first add the co2 to the tank, im going to have a major ph drop/varying ph and it will kill my fish. How can i avoid this/ will it happen.

Are there any other dangers of adding diy co2 to an aquarium, mainly dangers to the fish.

Thanks.

P.S. and i have roughly 2 wpg, and lotsss of plants


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## Philosophos (Mar 1, 2009)

I've never seen a single substantiated death related to DIY CO2 in any aquarium... ever. Maybe someone hooked up a 5 gal DIY to a 5 gal aquarium but that's about the only way I could see it happening.

Speaking of overkill DIY, may I recommend at least a good 6-8x standard size batch? The average batch of DIY CO2 strapped to a 20 gal will raise the CO2 levels by perhaps 5-10ppm. 2wpg also pushes the upper end of DIY's capabilities. You shouldn't have any toxicity concerns at 10-20ppm max, and it may be enough to make limiting CO2 less of a concern.

A needlewheel/fractioning impeller with a powerhead will get you far better mileage than chopsticks or air stones.

Consider excel dosing if you don't mind buying bulk.

Personally I'd just start saving for a compressed system; you'll pay less in sanity and excel.

-Philosophos


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## flashbang009 (Aug 6, 2009)

Yeah, thats what i've heard, save for a pressurized (just not feasible due to availability and price). My thinking is, i already dose excel, and get decent growth out of my plants, and i talked to a guy who did diy on his 55 planted, and he said it made a big difference in the amount of growth, so i was thinking i'd just start 2x 2 liters and see what happened. 

If i did try diy co2, would adding excel help any?

Also, if i understand what you're saying, with diy co2, i shouldn't even have to worry about my possibly low kh resulting in ph shifts?

Finally, With diy in a 75, should i even worry about an airstone at night?


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## flashbang009 (Aug 6, 2009)

also, this guy http://www.thekrib.com/Plants/CO2/co2-narten.html cites that he uses diy on his 55 gallon with noticeable growth difference. if i used 2 one gallon containers (i know just go pressurized) instead of 2 liter bottles, would there be a reason for concern yet about ph drops.


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## Philosophos (Mar 1, 2009)

flashbang009 said:


> If i did try diy co2, would adding excel help any?


If your CO2 is limiting, fluctuating CO2 levels will just cause a massive algae bloom. Excel will help to assure non-limiting CO2, and you can use it to spot treat some types of algae. Once your nonlimiting, CO2 fluctuations don't seem to be an issue.



flashbang009 said:


> Also, if i understand what you're saying, with diy co2, i shouldn't even have to worry about my possibly low kh resulting in ph shifts?


Nah, plenty of us run tanks with near nonexistent KH and pressurized CO2 that turns on/off at night. It's really fluctuating KH you should be concerned with. I have a KH of 3 from ADA aquasoil and my pH swings from 6.3 up to 7.1 on some days (tested with a good pH meter) and my fish don't seem to stress from it.



> Finally, With diy in a 75, should i even worry about an airstone at night?


Don't worry about that sort of thing, especially with 2x on a 75 gal. I don't do it with compressed right now and things are still fine. In your case, and most with DIY, you're better off avoiding surface disturbance to retain CO2.

This also means that HOB filters will not be your friend. If you must use a HOB, don't put it near the CO2 diffuser, and definitely don't go sticking your CO2 line into the intake. I'm not sure why people do this, but it violates common sense. CO2 is lighter than water; laying it out on the surface is going to decrease column saturation.

-Philosophos


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## flashbang009 (Aug 6, 2009)

Alright thanks, i have a canister filter, so the filter is not an issue. I think i will try a larger setup (i.e. 1-2 gallon setups), and see what happens. Besides, once i can afford pressurized, this will give me something to laugh at i suppose.


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## Jeanine (Apr 4, 2009)

I have a 55 gallon tank on DIY CO2. I use 2 1 gallon bottles switching them every 2 weeks or so. I just filled a bottle with a recipe using water from my fish tank and it seems to be bubbling away very nicely. I'm currently using a limewood block as a diffuser. It is right under the filter intake and all the little fine bubbles get sucked right in to the filter. It's a Fluval U4 underwater filter. So far this seems to work the best for me. I get pretty good plant growth. Make the best of the CO2 you can.


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## flashbang009 (Aug 6, 2009)

what recipe do you use for the one gallon containers?


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## Jeanine (Apr 4, 2009)

I use a 4L Ocean Spray bottle. In it I mix 4 cups of Sugar, warm water, 1/2 tsp baking soda, 1 tsp yeast.


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## Diana K (Dec 20, 2007)

Ditto Jeanine: Same ratio of sugar:yeast (no baking soda)
I have several bottles on my larger tanks, and swap them out in rotation. Once in a while I have started 2 bottles the same day, and even then the CO2 does not go too high, nor the pH drop excessively. KH is between 5-10 (tap water is 5 degrees, hard water tanks are 10 degrees or higher).


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## flashbang009 (Aug 6, 2009)

Alright, sounds like a good ratio, ill probably go with that. What would be a con for adding baking soda?


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## Philosophos (Mar 1, 2009)

With baking soda you've got the concern of sodium toxicity. In both baking and DIY CO2, too much sodium can be a toxicity issue. The acceptable ppm's for commercial yeast are beyond me, though I do know that some kinds of yeast have a greater tolerance than others. DIY definitely has room for improvement, so don't be surprised if you do some reading and find some kind of superior yeast for the job that can tolerate the sodium bicarb better. Just remember to account for doubling times when you crunch the numbers.

-Philosophos


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## flashbang009 (Aug 6, 2009)

Ok, i setup 2 1 gallon jugs so far, and im not getting great results. The first one i used room temperature distilled water, added 4 cups of sugar, 1 tsp yeast, and let it go. The second i used warm tap water with the same ratio. The second one now has many bubbles but the first one doesn't.

However, my main problem is this. When i fed the airline tubing down into the filter intake, obviously it filled with water up to the top of the aquarium. I let it sit overnight, and the water level in the airline tubing had gone down a lot. Will the air ever be able to come out of the end (i.e. will all the water ever evacuate from the tubing), and if it had sat overnight with two bottles hooked up, should it already have evacuated from the tubing???

Thanks


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## csf (Jan 30, 2006)

Keep an eye out on line for CO2 tanks and regulators used. You can start w/ pressurized w/o the pH regulator and then get a regulator later. It's about half the price of a full set-up.

$75-100 tank
$50 regulator (not a super whiz-bang one, but one that works)
$100-150 pH controller
$10-20 in misc hookup pieces (tubing, PVC pipe, etc.)


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## Philosophos (Mar 1, 2009)

I'll go one step farther; don't bother with the pH controller.

over 95% of the CO2 just gasses off anyhow, so if you can keep flow consistent you can keep a stable gas-off rate. Stable CO2 is far more important than stable pH from CO2; plenty of us have delicate spawning fish that experience large pH swings from CO2. It's the KH that really bothers fish. 

Not only that, the probe only measures on point in the tank, and it can be thrown off by other buffering systems in the column besides KH. Basically it's like having your CO2 hooked up to the pH-KH-CO2 method of calculation, which isn't as good as a drop checker, and I wouldn't trust the drop checker to automatically adjust my CO2 either.

-Philosophos


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## flashbang009 (Aug 6, 2009)

Alright, well i think i have a regulator from my dad's old kegerator or w/e they're called. Would i need to buy a new one if the other one is old though? 

Also, from what i'm hearing, all i would need would be the hoses and the canister then?

The reason i didn't want to go pressurized was the cost. I have a 75 gallon, so what size canister would i need, how often refilled, and how much (estimate) to refill it.

Maybe you guys can convince me after all


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## Philosophos (Mar 1, 2009)

I haven't known them to fall apart too quickly from age; they're usually built with the intent to be used for welding and such.

From there you'll want a solenoid ($25) needle valve ($5 for a cheap one) brass check valve ($5), bubble counter ($10) and to stay on the cheap side of things a needle wheel modded powerhead ($10-25) After that it's a matter of getting a canister; a 5lb runs about $90.

Basically $140 more to get yourself a full working setup. Keep an eye out though; you can grab things like bubble counters with built in check valves, used solenoids, etc.

-Philosophos


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## flashbang009 (Aug 6, 2009)

Well i have an old 5 lb canister, but for a 75 gallon, i thought that would run out way too quick.

Also, i think the regulator i have might have a solenoid? Ill take a pic of it tmrw morning


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## Philosophos (Mar 1, 2009)

A 5lb would probably last you a couple of months at a time. The nice thing about 5lb's is that lots of places exchange them on site. You can buy a bigger canister later and do an exchange for the 5lb while doing the 2 week send off for the larger tank.

If it's got a plug hanging off of it that makes some sort of thunk, ping, clang etc. when it's plugged in, you've got your self a solenoid. I find this is the most common piece of equipment to screw up, but most of the time it just involves a little grit in around a seal; a bit of cleaning usually fixes it up. I mention this because if it's been sitting a while, some dust may have accumulated in it.

-Philosophos


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