# Why use a Solenoid valve?



## ghostsword (9 Apr 2010)

Hi, It may be a silly question, but I am not really sure why would we use a solenoid valve, apart from saving on CO2.

If the plants consume CO2 during the day and release it at night, by constantly pumping CO2 into the tank wouldn't that ensure that there is always enough CO2 on the water for the plants?


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## ceg4048 (9 Apr 2010)

Hi,
    The primary advantage of the solenoid is NOT to lower CO2 consumption. That just happens to be a convenient indirect benefit. Injecting CO2 24/7 increases the physiological stress of the fauna. Therefore the overall injection rate must be reduced to accommodate them. When using a solenoid, the gas is shut down to allow them to recuperate overnight. This then allows you to drive the CO2 concentration levels to higher peak levels while the solenoid is in the open position during the photoperiod. Higher CO2 levels result in high O2 levels and better plant health overall. The gas can be shut off several hours prior to lights off to allow the residual levels to fall well below the discomfort limits, whereas with 24/7 the CO2 levels actually rises overnight since there is no consumption.

One really has to think about the penalty/benefit comparisons when deciding on whether to go 24/7 v solenoid. The factors to consider are the lighting levels, flow/distribution, type of fauna, bio-mass and so forth. Either technique works successfully, but the pitfalls are different.

Cheers,


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## nry (9 Apr 2010)

I use one to save CO2, though I wonder if the electric cost to run the solenoid is more than the cost of the CO2 I save


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## Dave Spencer (9 Apr 2010)

nry said:
			
		

> I use one to save CO2, though I wonder if the electric cost to run the solenoid is more than the cost of the CO2 I save



There is no electricity usage when the solenoid is closed, so you save on both accounts.  

Dave.


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## Ajm200 (9 Apr 2010)

I use one to stop the fish gasping at the surface overnight.  

Saw this once or twice with a DIY CO2 system on my smaller tank. Even had the shrimps clinging to the thermometer and climbing over each others backs to stay at the surface  Don't like to see the fish suffering.


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## ghostsword (9 Apr 2010)

ceg4048 said:
			
		

> Hi,
> This then allows you to drive the CO2 concentration levels to higher peak levels while the solenoid is in the open position during the photoperiod. Higher CO2 levels result in high O2 levels and better plant health overall. The gas can be shut off several hours prior to lights off to allow the residual levels to fall well below the discomfort limits, whereas with 24/7 the CO2 levels actually rises overnight since there is no consumption.
> Cheers,



Thanks ceg.

That is well explained. 

I don't have that many fish on my 120l, maybe 10 neons and about 4 cory's, but I got hundreds of cherry shrimps. Have not seen them yet at the top of the tank, so I guess that they are getting enough O2, and I got a air pump on the tank.

Will get a solenoid valve today and set it up with a timer. 

Probably could switch off the air pump during the day .. would that make sense?

Thanks.


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## Stu Worrall (9 Apr 2010)

have you got an air pump and co2 going at the same time luis?


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## ghostsword (9 Apr 2010)

Yes.. Shouldn't I?   :?:


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## LondonDragon (9 Apr 2010)

ghostsword said:
			
		

> Yes.. Shouldn't I?   :?:


Nope, that just drives off the CO2 you are pumping into it


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## ghostsword (9 Apr 2010)

Will switch it off today and put it on a timer. Soon I will have a timer per plug..  

Thanks.


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## LondonDragon (9 Apr 2010)

ghostsword said:
			
		

> Will switch it off today and put it on a timer. Soon I will have a timer per plug..
> Thanks.



Turn the air pump on after lights go off, then turn the air pump off about 2-3 hours before lights come on to allow the build up of CO2 in the tank for when the lights come on. That applies when you using a solenoid as well, and you might do without the air pump, just gradually reduce the times you have the air pump on over a couple of weeks to see the effect on the fauna, a sudden change might cause you issues as you might have to tweak the CO2 also.


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## ghostsword (9 Apr 2010)

Thanks, 

Will get three of these:






Will setup the air pump to come on when lights go off, and then to turn off a couple of hours before lights come on.

Now, should I put the Solenoid valve on at the same time as the Koralia? Do I need the Koralia when there is no CO2 being pumped on the water? 

I have a open top tank, so maybe I can do without the air pump, will test at the weekend and see what happens with the fish.

Thanks for the help, always learning on this hobby.


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## LondonDragon (9 Apr 2010)

ghostsword said:
			
		

> Thanks,
> Will get three of these:


I purchased these and they work great:
http://www.argos.co.uk/static/Product/p ... 822911.htm



			
				ghostsword said:
			
		

> Will setup the air pump to come on when lights go off, and then to turn off a couple of hours before lights come on.


Sounds like a plan 



			
				ghostsword said:
			
		

> Now, should I put the Solenoid valve on at the same time as the Koralia? Do I need the Koralia when there is no CO2 being pumped on the water?


The pumps also offer circulation and lift ditrus/fish waste from the substrate/plants to be picked up by the filter, up to you really, but I always leave mine on.


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## Stu Worrall (9 Apr 2010)

well, LD beat me to all the good advice but I concur with what he said   

Id leave the koralia on 24/7 too.


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## ghostsword (9 Apr 2010)

Thanks.. 

I will then leave the koralia 24/7. 

Thanks for the advice.


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## ghostsword (9 Apr 2010)

> I purchased these and they work great:
> http://www.argos.co.uk/static/Product/p ... 822911.htm



Great, even cheaper.. I will get these today.


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## tomsteer (10 Apr 2010)

I would second the Argos timers, Had a set for a few years now and they'v never let me down or lost/ gained time like some of the cheap ones do.

I'd never thought of putting an air pump on over night, I take it you could use a Y splitter and pipe it into your co2 diffuser to save putting more equipment into your tank?

Cheers,

Tom


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## Stu Worrall (10 Apr 2010)

tomsteer said:
			
		

> I'd never thought of putting an air pump on over night, I take it you could use a Y splitter and pipe it into your co2 diffuser to save putting more equipment into your tank?
> 
> Cheers,
> 
> Tom


nope, air wont go through a co2 diffuser.  youd have to put in a separate airstone.  ADA do air versions of their pollen glass which has a courser mesh, i guess becuase air molecules are bigger than co2 or something??


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## ghostsword (11 Apr 2010)

I got the argos timers, good piece of kit and very cheap. Easy to setup up as well.

I got a airstone, it does the job, and as the pump is now only at night I can decrease the CO2 going in.

Until I get the solenoid I manually shut off the CO2 in the evening and turn it on in the morning.


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## frothhelmet (20 Apr 2010)

Dave Spencer said:
			
		

> There is no electricity usage when the solenoid is closed, so you save on both accounts.
> 
> Dave.



This is incorrect. If you have no solenoid your electricity consumption is zero (but as was said, you waste CO2). If you do have a solenoid then you use no electricity when it is off, but you do use electricity when it is on (but you do not waste CO2). Therefore it is not win-win with a solenoid from an electricity+CO2 standpoint, but rather a tradeoff.

Cheers!


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## ghostsword (12 May 2010)

Today I got a scare on my tank, for the first time all my fish were on top gasping for air.

I setup the solenoid to stop CO2 at 2200 and start it again at 0530. It must have dosed too much CO2 into the tank, as at 0700 they were all gasping for air. 

I turned the air pump on and lit the lights, so that the CO2 drops during the day, and will check it again at night to see if I can get to a balance. 

Some fish I do not mind loosing, such as as the platies, but I really like my dwarf neons. Should be ok, but I was not expecting it with the solenoid. I was expecting some sort of lack of CO2, as it was stopped at night, not this.


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## Mark Evans (12 May 2010)

ghostsword said:
			
		

> Some fish I do not mind loosing, such as as the platies



you should be concerned for all fish my friend.


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## ghostsword (12 May 2010)

saintly said:
			
		

> ghostsword said:
> 
> 
> 
> ...



I should, I know I should ..  and I do not want to cause them suffering, but there are some that are my favourites..


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## Ajm200 (13 May 2010)

I hope the fish are ok.  A quick water change helps in that situation.  Maybe you can turn the co2 off a bit earlier to give the fish a break.  I may be wrong but the plants shouldn't need the co2 on for that long.  Turning it off a bit earlier an hour or two before the end of the photoperiod will allow the plants to use up some of the excess making it easier for your fish to cope when the lights go out and the plants  start using oxygen and releasing co2.

I now have the co2 on several hours before the lights go on and turn it off 3 hours before lights out.  Still got a shock a couple of weeks ago when I tried to add new fish hours after the co2 stopped and nearly lost them as the co2 levels were still too high for them.


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## ghostsword (13 May 2010)

Thanks,

All the fish are ok, and there were no losses. 

I will turn off the CO2 two hours before end of photo period, at 2000, and then allow CO2 to start again at 7am, an hour after air pump gets turned off. 

The air pump starts at 0000 and turns off at 0600, so that gives the fish a break.

The tank is not big, so the onus is on me to sort it out. 

It was working perfectly when I had the CO2 24/7 and the air pump only at night, so it is odd that problems started when I added the solenoid.


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