need ur opinion....

2 or 3 will work. Some people prefer 3 just incase the fish need a place to relax, and to help remove surface film.

 

I use 3. Not just for the fish or film but because O is as important as CO2 for the plants!!!

AC

 

If your light intensity is low enough, you won't need a high concentration of CO2 in the water, so you can run a lower bubble rate, and run it 24 hours a day, if you wish - people with DIY CO2 commonly do this. Then, you don't need as much surface agitation, and with DIY CO2, you will want only a small amount of surface agitation.

But, when you start using higher light intensity, you need more CO2 concentration to avoid limiting the plants growth rate by having too little CO2. Then, it is harmful to the fish to run that much CO2 24 hours a day, and the fish need a good concentration of O2 in the water to be able to tolerate the CO2 even during the day, so then you need very good surface ripple, and you need to shut off the CO2 when the lights are off. I don't use all that much light intensity, but I still treat it as if I were.

 

I'm confused. What is the difference between agitation and "some surface movement(never enough to break the surface)". I'm about to add pressurized CO2 to a tank next weekend (my first time with CO2) and am switching to a canister filter to minize surface agitation. Thank you.

 

Look at the pictures in http://www.barrreport.com/general-plant-topics/5085-how-much-surface-ripple.html . That shows what type of surface movement you want. You don't want splashing, or "breaking waves", where water falls back into the tank.

 

Sorry if I am being thick here. My understanding is that aeration will cause CO2 loss by disturbing the surface. Thus, when I hear agitation I think of a disturbed surface and CO2 loss. I have read on other forums that canisters, instead of hob's, should be used with CO2 as hob's disturb the water surface and thus cause CO2 loss. Am I misunderstanding what Vaughn and others mean by agitation? Do they mean circulation? Thank you.

Greg

 

Okay, I think I have the idea now. It is a balancing act/tradeoff. While less agitation means less CO2 loss, it also means more O2 in the water and less scum accumulation. With pressurized CO2, the loss can be compensated by increasing the CO2 injected. Basically I am just going to have to set it up and adjust as I go. I think the real problem is I am an accountant and sometimes forget that the world isn't a set of numbers that either add or don't add.

I was just reading the thread Vaughn linked. I can't get the pictures to display. What am I not doing right?

Thanks again.

 

Thanks Tom, Thanks Vaughn, I'm looking forward to first attempt at CO2 next weekend.