[petman12345]

I have learned alot on this site it has been a great source of answers for me. I now have a question. I have been using 1 2 litre bottle for my CO2 mix and it only goes about 10 days in my 75. I read on here about doing 2 bottles together can someone please explain how and how often I would have to change them. both at the same time? How do I tie the 2 together or do I use 2 diffusers in the tank? Thanks for the help..:help:

 

[eser21]

you can do it anyway you like but youll need a lot more than 2 bottles for DIY CO2 in a 75 to work. DIY is best saved for less than 30g.

 

[Higher Thinking]

You would be saving yourself a great deal of time and energy if you could save up for a CO2 tank and regulator. I know that isn't exactly the answer your looking for, but DIY on a 75 will be tough.

I've never done it like before, but I'm assuming you could run each of the bottles the same as you are now, but get two check valves on each line and then after the valves bring them together with a 2-to-1 hose fitting. Obviously this would make the mixture last any longer but it could produce twice as much CO2 for your tank which is likely the minimum you will want.

 

[radioman]

I would go with a t connector to connect them. To make it last longer add less yeast, but then you will also get a lower bubble rate and would have to connect more bottles together.

 

[petman12345]

Thanks for all the help. I did see a big difference in the growth rate when I added CO2 so I guess it is doing something. Thanks again.

 

[mistergreen]

You don't have to get CO2. The plants will grow a lot slower. Perhaps invest in buying a lot of plants instead.

 

[IxIBluepitIxI]

One DIY bottle on a 75 gallon that's like throwing a couple handfuls of potting soil in the Grand Canyon and saying "What hole?" the fact that your seeing plant growth is more likely your doing and the CO2 requirements of the plants you have in the tank. So pat yourself on the back for that much. Did your ph drop when you used the bottle, are you using any carbon substitutes like Seachem Excel?
You can hook together many bottles and just use ONE check valve at the single line goes into the tank. That would be a cool experiment to see how many bottles of yeast mixture it would take to achieve an acceptable level of CO2 in a tank that size then calculate the cost of ongoing upkeep and opportunity cost to maintain that level of saturation.