Increasing output of Hagen Plant-Gro CO2 Natural System

[gheitman]

I don't know if anyone else has come across this or not, but changing the type of sugar you use in the Hagen Plant-Gro CO2 Natural System (and I suppose the DIY yeast systems) can make a difference in how quickly CO2 is generated. The directions say if you use normal granulated white cane sugar you will get enough CO2 generated for a 20 gal tank and it will run 30 days.

I have one of these CO2 systems in a planted 30 gal tank and I could never get pearling of oxygen off my plants. I talked with the owner of my LFS and he said Hagen told him that granulated white sugar in North America uses grains that are too small and it doesn't provide enough surface area for a good reaction. Hagen suggested using dark brown sugar instead. I tried the dark brown sugar and I noticed that the speed of generation of CO2 went up about three times what it had been before. Now I am getting pearling off of my Anachris. My other plants are taking off as well.

The only down side is that I have to refill the canister with sugar more frequently now (about once every 7 to 9 days). I decided to do some further testing using raw cane sugar because it has bigger grains. The CO2 output was roughly twice what I was getting with white granulated sugar and it lasted about 15 days before I had to refill the canister.

I've been using the dark brown sugar for generating CO2 with my 30 gal tank for several months now and I have been completely satisfied with the results. My Amazon swords have taken off like crazy and my Telenthera is shooting to the top of the tank. The tank has a 96W CF lamp and I fertilize it with Flourish Tabs, Flourish and Flourish Iron. I'll post some pics when I get a chance.

 

[malkore]

Its' because the molasses in the brown sugar is already partially dissolved, so it's more readily digested by the yeast. White sugar is actually kind of 'dirty' in some respects...home brewers use corn sugar that's ground to a consistency close to confectioners sugar (but heavier) because yeast does better on this. however corn sugar is about $1 per pound around here, so I stick to generic white sugar.

However what your LFS told you is bogus. The sugar should be dissolved in the water, to grain size means nothing, because it's no longer a solid, so surface area of the grain is a moot point.

If you're happy with the sugar, stick with it. However the little grey canister that comes with the unit isn't good for anything larger than 10-15gallons...a bigger reaction chamber should be used when you get to 20gallons.

 

[TankGirl]

I agree - my sugar is completely dissolved with hot water, then cooled before adding the yeast, before I hook it up. You can still use the cool ladder diffuser but a 2 liter soda bottle will provide longer CO2 production for you, or maybe you could run 2 juice bottles (they are not quite 2 liters) for a 30gal.

What's your rule of thumb for how many bottles of DIY for the size of the tank, Malkore?

 

[malkore]

Well, a lot of it varies due to water chemistry (mainly Kh levels which determine how readily the CO2 will dissolve).
On average I'd say 1gallon for every 20 gallons, and you can adjust between 1.5 and 2 cups of sugar depending on the tank size.

I did do a little more thinking, and I could see an argument being made for grain size/surface area if you were using the little grey hagen canister. They have you put close to 3/4 cup of sugar in that thing...you end up with with 40% sugar and 60% water...so not all the sugar would dissolve right away. However if the brown sugar did dissolve, then it contains less sugar by volume, so you'd get less Co2 in the long run.