new 5g DIY CO2 tank

Since my spring break is spoiled by four exams in three days immediately following it, I decided to make a new tank to kill time between studying.

Found a 5g hex tank with biowheel and 10w fluorescent lighting for $27, got silicon airline tubing ($3), a pack of disposable airstones ($2), a 2-litre of generic fruit punch ($.7), some airline suction cups ($2), two packets of generic gelatin dessert ($1 each), a hefty bag of sugar ($3), a taped-up 10g bag of black gravel that was reduced for quick sale ($3), and some active yeast ($1).

In go an amazon sword that was ambushed by a ravenous snail, a paradise fish, and a bunch of wisteria. The fruit punch (already laden with sugar) went on the boiler with two packs of generic lime jell-o, making a lovely odor. The mixture was poured into the 2-Litre, along with another two cups of fruit punch. In goes an amount of sugar that would have an entire kindergarten class climbing the walls, and a wee bit of baking soda... The supersaturated solution is cooling in the fridge right now- once the mixture is ready, in goes the yeast and warm water.

Really excited about my new project.. Looks great so far- the tank is on top of my dresser, and the airline feeds down below my bed to where the bottle will be hidden. The lid to the "reactor" is curing and will be ready to rip tomorrow. Our water is quite buffered, but I have my pH kit ready to test to make sure everything's stable. Going to test every couple hours once the bubbling starts, and make adjustments as necessary...

Sound good? Once this thing's up and running, it will be my QT tank / shrimp tank. I've got my eye on a couple plants at the LFS that I want to try out- mainly the "underwater palm" and an anubias of some flavour.

I've kept an eye on them, they've been submerged for two weeks, and still are green and growing. Gonna look for a scientific name to see exactly what I'm dealing with.

Hmm- read a site saying that it'll eventually wither underwater... Shame- it looks absolutely amazing. Going to see if there's any way I can cross reference that. Thanks for the heads-up.

I'm gonna do a trial run keeping the gourami in the 3g until I'm sure I can get a decent level of CO2 in there. Hopefully the jell-o will keep the yeast from pumping out too much CO2.

this is just a trial run- gonna tailor it with the next batch. If it's too much, I have a VERY heavily planted 10g that I will hook this unit up to... I can always try for smaller batches with the 5g.

It's a function of exponential growth- the larger the number of organisms you start with, the faster they grow. Start small, they'll produce less CO2, and the media will last longer... And so long as they use up the media before they grow to reach the threshold of excessive CO2 production, it should be fine.

Thankfully, my tap is wonderful in both pH and kH. Not too hard or alkaline, but with plenty of buffering capacity. And since I do large changes bi-weekly and test parameters religiously, I don't think pH crashes will be an issue.

Here's a question: would it be better to CO2 my 30g (wisteria and java moss) and leave the 5g for another weekend, possibly when I have the recipe down? The 30g would give me a lot more leeway, parameterwise... I won't have to move my gourami...

I'm thinking that sounds like a much better plan of action. Any and all input is appreciated!

30g:

10:00- (.25 tsp Yeast) Added to Reactor. gH = 4.0°H , pH = (7.8 by low range, 7.6 by high range) No sign of yeast activity yet. Topping off tank to try and minimize surface agitation.

12:30- bubbles visible in reactor, water pushed out of airline tubing. Looks like it's working. Checking pH at 2:00.

2:00- bubbles coming from airstone at a rate of 1-5 pinhead-sized bubbles every second. No change in gH or pH.

6:00- no change in gH or pH. Checking again at 9

9:00- no change in gH or pH. Removed CO2 unit from water, will place in the tank 1 hour before lights come on at 10.

The project tank is coming along. I hooked up a 1 litre jello media with ~1/8th tsp yeast dissolved in warm water with some sugar two days ago, and got some new plants today.

Today I added bacopa and a crinium bulb to the bit of floating wisteria, the recovering amazon sword, and a nice blanket of java moss that were in the tank. We'll see how well these like the CO2 system in a couple days. They look spectacular.

So far, the pH has only decreased about .3-.4 during the day and rebounds at night once the CO2 is off. There's no noticeable decline in gH yet.

the 2 litre model I made is now on my 10g, and params are quite stable... Seems to be a success so far. Thanks for the guidance!