... but I understand it should be turned off at night when the plants aren't consuming co2... in the DYI version, how do you turn it off?

It is true that plants consume o2 at night instead of CO2, however, I would not recommend "turning off" a DIY reason because it cannot be controlled like a pressurized system. You are likely to introduce dangerous Ph swings by attempting to "turn off" your DIY CO2.

If you feel that your fish could use more Oxygen at night, or if they are gasping at the surface in the morning, simply get an air stone, and run a pump on a timer.

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29 Gallon Planted
1 Angelfish; 2 German Blue Rams; 11 Rasbora Boraptensis; 3 Khuli Loaches, 1 BN Pleco

20 Gallon Planted
2 German Blue Rams; 5 Corydoras Paleatus; 4 Otocinclus Catfish; Amano Shrimp

5.5 Gallon
Betta, Some plants.

Another thing DIY co2 won't put as much in the tank as pressurized would. Diy fluctuates to much to keep a steady flow going 24 hours.

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SUCCESS IS MEASURED BY YEARS, NOT MONTHS!!!
220 Tank build
http://www.aquariumforum.com/f15/sta...late-3253.html

Ok so say I get involved in a pressurized system. I've got a 75 gallon tank.. what would the upkeep cost?

Just the initial cost is the most expensive, refills depending on the size of the tank should be only once every 8 to 12 months.

Compared to the cost of mixing the diy every couple of weeks you end up saving money in the long run.

__________________
SUCCESS IS MEASURED BY YEARS, NOT MONTHS!!!
220 Tank build
http://www.aquariumforum.com/f15/sta...late-3253.html

Plus I was told with a tank my size (75 gal) the DIY really isn't strong enough. Guess I'll start looking into a Co2 system... and here I thought I was done. Damn! LOL!

On a 75 it would take too many bottles of co2 to even show much difference.

__________________
SUCCESS IS MEASURED BY YEARS, NOT MONTHS!!!
220 Tank build
http://www.aquariumforum.com/f15/sta...late-3253.html

You will never be done grasshoppa.