co2 distrubition question - The Planted Tank Forum
 
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post #1 of 15 (permalink) Old 08-09-2010, 11:14 PM Thread Starter
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co2 distrubition question

Ok so I am just setting up pressurized co2 in my 65gal. I had planed to use 2 power heads to diffuse it but when I hook them both up bubbles only come from one. When I kink that hose they come from the other. I also have a glass diffuser that I could use. I thought that having it come from each side would give the best distribution which is why I got the 2 power heads. So what do you think - co2 from one power head on one side only(some bubbles are going to the other side of the tank this way) or the glass diffuser in the middle on the back (the bubbles just go up but some are pushed down and to the middle from the hob flow). Also how can I get the co2 to both powerheads. I under stand the path of least resistance but all the hoses are the same length etc. so I thought every thing would be even, although the powerhead that bubbles is closer to the tank if that matters.
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post #2 of 15 (permalink) Old 08-10-2010, 12:03 AM
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You need one of those cheapo flow control valves that come in the airline kits. Hook one to each line and adjust them 'till there's bubbles from both power heads. It'll probably get brittle eventually, but since theyre super cheap, who cares?
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post #3 of 15 (permalink) Old 08-10-2010, 12:12 AM
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You might want to ditch the powerhead idea and go with a true needlewheel setup... I've heard of decent results from just using a Rio 800rvt. Any reason you don't want to just run an inline reactor?
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post #4 of 15 (permalink) Old 08-10-2010, 12:32 AM Thread Starter
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Thanks Sharkfood that was a slap to the forhead idea. I found a valve that came with an air pump and now I have bubbles everywhere. I might to the the LFS tomarrow and get a metal one but for now it the plastic one is working great. Xmas one I am using powerheads because that is what I have. I have been running diy through them for the past couple of months and it has been working fine but the I had a bottle for each powerhead then.
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post #5 of 15 (permalink) Old 08-10-2010, 12:46 AM Thread Starter
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Well on second look the valve was just introducing lots and lots of air. Good idea though maybe the metal gang valve from the store will work better. Thanks
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post #6 of 15 (permalink) Old 08-10-2010, 01:20 AM
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are the two pwerheads the same brand / size? Silly question, because if you have the CO2 lines hooked up to the venturi port, then which ever pump provides better suction will be favored. Try an independent check valve before each check valve if so.
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post #7 of 15 (permalink) Old 08-10-2010, 01:46 AM Thread Starter
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They are both exactly the same - AquaClear 30s' except one is a couple of months older. I just don't understand why if everything is the same why only one bubbles when both are hooked up.
So if I only use one then does it make a difference? There are small bubbles across the tank from the powerhead so should the distribution be ok?
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post #8 of 15 (permalink) Old 08-10-2010, 02:01 AM
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Are you using the venturi input or introducing the flow to the intake side and impeller chopping them?

In either instance, a loss of flow to a powerhead (eg plant matter clogging intake) will reduce the suction on your CO2 input, and then you would get one powerhead prefered over one if the CO2 comes from the same source.
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post #9 of 15 (permalink) Old 08-10-2010, 02:15 AM Thread Starter
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I am using the venturi.
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post #10 of 15 (permalink) Old 08-10-2010, 06:03 AM
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The reason why you are only getting co2 to one ph is that the co2 will travel the path with least resistance. I bet it's going to the ph that has less tubing. To get thhe co2 to both ph's, you need to put a valve on the line that the co2 is already coming out of. Fine tune the total amount of co2 with your needle valve. Then use the other valve to get the distribution you want. Don't get those plastic valves, they leak. A metal gang valve may work but I'm not sure how leak proof they are.

The best, but not cheapest, solution is to run a manifold with 2 seperate lines and a nv on each. Then each line would go to a ph.
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post #11 of 15 (permalink) Old 08-10-2010, 07:56 AM
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As long as you have separate controllers for each outlet and enough pressure in your delivery pipe - there should be no problems in supplying to both the power-heads.

If you have a choice, you have a problem, till you elect your choice. No choice, no problem, only consequences, learn to live with them.
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post #12 of 15 (permalink) Old 08-10-2010, 03:46 PM
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Valves sold for air line use are useless for CO2. In air line use a valve can leak a bit and it makes no difference, but for CO2 use no leakage is acceptable. Air line valves aren't made to be zero leakage. You need separate needle valves for each CO2 diffuser device, with a bubble counter on each if you rely on a bubble counter to determine how much CO2 you are supplying. GLA sells some stuff that will work very well for that.

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post #13 of 15 (permalink) Old 08-10-2010, 04:05 PM
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Quote:
Originally Posted by Hoppy View Post
Valves sold for air line use are useless for CO2.......GLA sells some stuff that will work very well for that.
Agreed, I was supplying two tanks from one regulator. Both were being fed to a powerhead in each tank. One needle valve and one airline control valve. I could get some control over the CO2 flow but the next day it would be way off again. I had the cheap valve under water and there was no signs of leakage, just not good control.

Orlando at GLA had an inline needle valve made to suit my needs in a couple days.

I'm guessing the sponge prefilters on the pumps were fouling at different rates and causing most of the issues.
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post #14 of 15 (permalink) Old 08-10-2010, 11:04 PM Thread Starter
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First, thanks everyone for your replies, I appreciate the help. Second is it only important to get the co2 into the tank, meaning as long as it is being diffused somewhere and you have good circulation in your tank it will be distributed everywhere or do you need to have more than one distribution point to begin with? Thanks again
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post #15 of 15 (permalink) Old 08-11-2010, 01:38 AM
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Getting good CO2 distribution to all parts of the tank has been very difficult for me. I've drastically upgraded my water flow and moved inputs/outlets around, but still have low flow areas in the back corners and spots that seem to get lower CO2 in or near very dense stands of stem plants.

I think most tanks with dense growth will take some personal customization and tweaking to get the best CO2 circulation. Thick vegetation seems to strip CO2 out of the water much faster than I ever would have guessed possible before working with pressurized CO2.
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