# Recommend a needle valve?



## greenink (9 Jan 2014)

Having real trouble adjusting CO2 precisely. My all-in-one solenoid, needle valve, pressure gauge from china is great and cheap but WAY too sensitive - turn the dial 2mm and you double CO2. 

Can anyone recommend a needle valve I could put inline that is really easy to fine tune? Fed up of looking like I'm trying to crack a safe!


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## geoffbark (9 Jan 2014)

I use swagelok and hoke micrometer needle valves. They are easy to adjust they have gradients on the handle so that you know how many turns you have operated. They are more expensive than the needle valves found in the aquatic shops but 10x better. And they do come up on eBay now and again.

this is a good thread to read

 Metering(needle) valves for our DIY CO2 system - Aquarium Plants


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## greenink (9 Jan 2014)

thanks, v helpful


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## greenink (9 Jan 2014)

actually, can't make head nor tail of this in terms of gauges and Cv. All a bit complicated.

essentially I want something that will allow me to fine tune the CO2 input for a 480l tank, where a big turn of the dial results in a small change in CO2!

Is this the kind of thing?

 Swagelok SS-1RS4 | eBay


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## geoffbark (10 Jan 2014)

Cv is the Flow Coefficient, (in fear of getting shouted at!!!!) it does not really tell us anything unless we know Pressure drop (Dp) and specific gravity (Gf) etc.
You need to measure how much co2 you are using per min in ml and then look for a valve that will provide this and a bit more with at least 8 turns on the handle. The thread above has done this for you 

The valve you have found on ebay may still be a bit crude but a step in the right direction.

I think these are quite popular Fabco NV-55-18

These as well
 Hoke 1325G4B, Milli-Mite 1300 Series Adjustable Valve | eBay


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## greenink (10 Jan 2014)

Thanks perfect


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