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CO2 ignorance - solenoid usage?


25 Jun 2009
Basingstoke, Hampshire
Hey guys,

I recently treated myself to a Do!Aqua CO2 (against advice :shh: ) as I wasn't too worried by the cost of the cylinders and wanted a small setup. Perhaps as I get used to it I'll upgrade to something bigger. The plan is to buy the cylinders in bulk in advance so I won't be caught short.

To save my precious gas I was looking into a solenoid. Would this sort of thing do the trick? I don't mind paying for quality if it will last.

What is the best time to set the gas to come on for? an hour? Im suspecting that the plants will stop photosynthesising on lights off so I can cut it off then?

Thanks in advance for any advice offered

At the moment mine comes on 3 hours before lights and goes off 3hours before lights but this varies from tank to tank. Most people aim for a lime green drop checker at lights on and switch off as late as possible without gassing fish. Read the co2 tutorials they will explain better. Its about balancing injection rate and injection period to provide plenty co2 for plants and not too much for fauna
Hi Neil, mines pretty much the same as big clowns. My Co2 comes on 3hrs before lights on and goes off 2hrs before lights off. My injection rate is very heavy though, i can't even count the number of bubbles per second (i have very hard water). Clive has written a great tutorial, which has helped me immensely.

Check this out - CO2 MEASUREMENT USING A DROP CHECKER | UK Aquatic Plant Society
I would be cautious about this as I and s friend of mine have both attempted to use a solenoid on small disposable kits and it just did not work. The problem as far as I could work out was that the flow regulator is just that, a "flow" regulator so basicly just a needle valve. We both found that when the solenoid was closed gas would find its way out and a 95g bottle would empty in about 3 days.

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Yes ali is right its not a regulator just a needle valve so when solenoid is closed pressure equalises with bottle and it dumps a lot more gas when solenoid opens resulting in the bottle running out much quicker. Another alternative is buying a disposable welding reg from machine mart(theres a thread somewhere on ukaps) and adding a solenoid and needle valve but by the time youve refilled a couple of times you may aswell just buy a cheap fe and reg