DIY CO2 System - what should I look out for?

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Aquarium Advice Addict
Jul 12, 2004
Northern VA
I am going to be setting up a DIY CO2 system, and I was wondering if there are specific things I need to be on the lookout for. Like how much will my pH drop, what test kit should I get to monitor levels or either oxygen or co2 (is there a test kit?). In general I would love to hear your pearls of wisdom :D

Here is a link if you are interested in the DIY cheap method.

This is basically what I used when my 75gal was a FW planted tank. 2 liter soda bottles work great. I used the tetra difussion bells and just filled them once a day with airline tubing. Caution some recommend just running a line into you tank or leaving the airline hooked to your diffusion bell. Do not do this as it could create a siphon and start to drain your tank(learned the hard way )
If you do want to use the bubble method make sure you have a check valve.

I never tested for CO2, just filled the diffusion chambers daily and my plants thrived to the point I was harvesting them and selling to LFS.

Good Luck,
BTW, another secret to my success with live plants was seeding the substrate with laterite when I set up the tank.
Thanks guys, I found what I needed. It is the KH I need to monitor to make sure my pH will remain steady. Those articles were great!

"One caution: keep track of your KH (Carbonate Hardness) readings of your water, since CO2 forms a weak acid (Carbonic Acid) that can slowly reduce your KH levels in your water. If KH is allowed to reach zero, pH can drop precipitously. If your KH reads less than 4, try adding a little Sodium Bicarbonate (Baking Soda) to increase KH. Regular water changes become vitally important in tanks with supplemental CO2, since water changes will constantly replenish the water's natural buffers, helping to maintain a more steady pH."
I used crushed coral in my filters to maintain KH - there are a few threads going about CC if you want to look into that. I find it much easier than adding baking soda, but Mark prefers the baking soda method - more precise and more control.
But keep in mind, you pH WILL go down when you inject CO2. Yes you wanna make sure Kh doesn't fall, but weekly water changes with semi-hard water ensure good Kh levels.
Just my opinion but if you're serious about getting into C02 I'd go for the pressurized system right off the hop. You'll have a higher and steadier concentration of C02 as with yeast the concentration drops over time. Get the milwalkee regulator on the net, you should be able to find is for $56. The 20lbs tank run about $80/year.
if you found that regulator for $56 online, please share the link...cuz a year ago I found the cheapest source was on sale for $79.

Also, just to clarify, it's not $80 a year for a 20lb should be more like $80 for a deposit on the tank, and 20lbs should run a 125gallon tank for at least a year. A refill on that size tank might run about $30 - it really depends on where you live and where you get it filled though. It's about ?$17 for my 5lb cylinder fill at a welding shop.
Wow. I buy from them all the time!

I've been pondering running pressurized on my 2 20gallons which are side by side upstairs.

But I also want a UV sterilizer and a second canister on my 75g.

So many ways to spend lotsa cash :(
Easy. Pressurized upstairs this month, UV and 2nd filter next month. :D

No, wait, you still need to get some color filled in on the koi, dont'cha? I think that might be priority this month.... :wink:
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