# Fabco needle valve ... how low should it adjust?



## DaveS (Jun 9, 2006)

I am helping my brother setup a pressurized CO2 system, and he went with the Rex regulator with the Fabco needle valve "upgrade". He is running the needle valve inline as suggested. The lowest bubble rate we can adjust the valve to is probably somewhere around 1.5 bps. Is this normal? I was expecting to get a much lower potential bubble rate than that. At 1.5 bps the CO2 concentration is greater than 30ppm which hasn't been a problem yet, but it still seems less than ideal.

Thanks,

Dave


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## orlando (Feb 14, 2007)

Try to lower the working pressure as much as you can to fine tune the valve..


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## hoppycalif (Apr 7, 2005)

How big is the aquarium? And, how are you measuring the ppm of CO2 in the water? Unless you use a drop checker, with 4 dKH distilled or deionized water in it, you can't accurately determine how much CO2 is in the water. 1.5 bbs is likely to be as low a bubble rate as you would ever need for any tank 20 gallons or bigger.


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## DaveS (Jun 9, 2006)

Thanks for the replies.

The tank is 58 gallons. I assumed that because the pH drop was about 1.3 points that the dissolved CO2 must be over 30ppm unless my understanding of the pH/KH/CO2 table is incorrect.

Dave


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## NoSvOrAx (Nov 11, 2006)

Using a screw driver to make the adjustment?


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## gibmaker (Jan 3, 2007)

hoppycalif said:


> How big is the aquarium? And, how are you measuring the ppm of CO2 in the water? Unless you use a drop checker, with 4 dKH distilled or deionized water in it, you can't accurately determine how much CO2 is in the water. 1.5 bbs is likely to be as low a bubble rate as you would ever need for any tank 20 gallons or bigger.


I use a drop checker with a 4dkh standard solution and I have about 2 to 4 bubbles per minute on my 125 gal and the drop checker is a nice dark green. I used distilled water to make the solution and I used billionz method to make it. (I think that is his user name)


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## gibmaker (Jan 3, 2007)

I should also mention that I have a rex system as well. I had the fabco needle valve and it failed on me, I paid the extra dough for the better needle valve that he offers, and WOW what a difference.


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## hoppycalif (Apr 7, 2005)

gibmaker said:


> I use a drop checker with a 4dkh standard solution and I have about 2 to 4 bubbles per minute on my 125 gal and the drop checker is a nice dark green. I used distilled water to make the solution and I used billionz method to make it. (I think that is his user name)


I don't believe it is possible to maintain 30 ppm of CO2 in a 125 gallon tank with only 2 to 4 bubbles per minute. It might barely be possible at 2 to 4 bubbles per second.


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## gibmaker (Jan 3, 2007)

hoppycalif said:


> I don't believe it is possible to maintain 30 ppm of CO2 in a 125 gallon tank with only 2 to 4 bubbles per minute. It might barely be possible at 2 to 4 bubbles per second.


Believe what you want my eyes don't lie as a matter a fact this morning when I looked at it, it was on the yellow side rather than green. I use the internal external mix max co2 reactor. If I had a way to post a video of my bubble counter and then show you my drop checker I would, but IMO it's not worth it for arguments sake. I don't just make stuff up. I also use the reactor internally. Best reactor I have had and I went through about 4 or 5 of them, speaking of which if you want to buy an aquamedic 1000 cheap it's yours, it collects dust in a box in my basement, make me an offer, anyone.


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## DaveS (Jun 9, 2006)

Regardless of bubbles per second, minute, etc ...

If you measure your pH before CO2 is added and then measure a full point drop after adding CO2, that corresponds to 30ppm CO2 right? I realize that measurements need to be made over the period of a few days to account for normal pH fluctuation that might occur throughout the day. This tank does not have a drop checker but it does have a Pinpoint pH probe, so I think the measurements are pretty accurate.

Dave


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## DaveS (Jun 9, 2006)

I might also add the both my brother and I are colorblind, so I don't see a drop checker making much of an impact on us  This is the main reason for using pH measurements to determine the CO2 level rather than a drop checker.

Dave


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## DaveS (Jun 9, 2006)

I don't know why I thought 30ppm correlates to a drop of 1 pH point. After looking at the chart again, I believe I see where I went wrong.

I will look at the numbers again, but I just wanted to verify the needle valve was operating about as it should be expected to.

Dave


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## hoppycalif (Apr 7, 2005)

A one point drop in pH means the ppm of CO2 is 10 times higher than it was at the higher pH. So, if the water contains 3 ppm to start out, it would contain 30 ppm after the one point drop in pH. But, this would only be true if nothing else changes in the water between those readings - no more tannins, no more phosphates, same KH, etc. And, there is no good reason to expect the original pH reading to coincide with 3 ppm of CO2 instead of .5 ppm for example, which would mean you only have 5 ppm with the one point drop.


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## mikenas102 (Feb 8, 2006)

I don't know if you have the same Fabco as me, but I have the Fabco NV55 from Rex. I can adjust it down to as low as 1 bubble every 10 seconds. It is FAR superior to the Clippard needle valve that he used to use on his regulators. Either your working pressure on the regulator is way too high or your needle valve is not right (assuming you have the same model Fabco valve as me).


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