Solenoid for venturi into skimmer

[mangeltrueman]

I have one of these All Pond Solutions surface skimmers which has a built in venturi. Its great for a bit of extra oxygenation, but i only want it sucking in air and blowing out bubbles during the nighttime really. I wanted to see if i could stick a solenoid on it to control that. I tried the solenoid that came with my colombo co2 reactor but it seems to require a certain amount of back pressure to allow any gas through (which it gets with the pressurised co2) and doesn't work when "just allowing air in".

I saw a "similar" solenoid on aliexpress which i thought might do the job, but not sure.

I thought maybe a cheap air pump would work just as well but not sure if it will restrict air flow when turned off.

Any ideas how to handle this? Solenoid seems the obvious choice to me but not sure if they all have some requirement for pressure on the "input" side of things.

 

[jamiep]

not really the question you're asking, but I too use their [other, larger] skimmer for increasing nighttime flow (a la Amano raising his lily pips) just by having it on a smart timer plug

this one, but it is cheaper direct from APS, but their site is currently down for me to do a link
Amazon product ASIN B01LX152XH

 

[Wookii]

I have one of these All Pond Solutions surface skimmers which has a built in venturi. Its great for a bit of extra oxygenation, but i only want it sucking in air and blowing out bubbles during the nighttime really. I wanted to see if i could stick a solenoid on it to control that. I tried the solenoid that came with my colombo co2 reactor but it seems to require a certain amount of back pressure to allow any gas through (which it gets with the pressurised co2) and doesn't work when "just allowing air in".

I saw a "similar" solenoid on aliexpress which i thought might do the job, but not sure.

I thought maybe a cheap air pump would work just as well but not sure if it will restrict air flow when turned off.

Any ideas how to handle this? Solenoid seems the obvious choice to me but not sure if they all have some requirement for pressure on the "input" side of things.

Could you not just use the "cheap air pump" idea, and simply site a small airstone underneath the outflow from the skimmer?

 

[mangeltrueman]

Could you not just use the "cheap air pump" idea, and simply site a small airstone underneath the outflow from the skimmer?

Yeah, it certainly a possibility, one that I overlooked in my overengineering of the solution to the problem 😀

 

[mangeltrueman]

I ended up buying one of the below and wired it up to a 12v plug i had hanging around. As it's a normally open solenoid, i put it on a double plug with the solenoid for my co2, that way as soon as the co2 solenoid turns on, the oxygen solenoid turns off and vice versa. Connected it up to the air line on my skimmer venturi. Works a treat and dont need another bit of hardware in the tank.

Normally Open Solenoid

 

[mangeltrueman]

not really the question you're asking, but I too use their [other, larger] skimmer for increasing nighttime flow (a la Amano raising his lily pips) just by having it on a smart timer plug

this one, but it is cheaper direct from APS, but their site is currently down for me to do a link
Amazon product ASIN B01LX152XH

I missed this response, sorry. Yeah i could put the skimmer on a timer, but i like the extra flow that i get from it 24/7 so just wanted to time the venturi.

 

[Wookii]

Hi @Stan510 I like the thought and I am (still) intrigued about the idea ... even if its just an extra ppm or two of CO2 above equilibrium, it would be worth it IMO - the air we breathe is ~400ppm of CO2 after all. I wish one of our experts would comment on it.

Cheers,
Michael

There is some debate on the exact quantity of dissolved CO2 when it’s an equilibrium with the air, but it’s somewhere between 0.6ppm and 3ppm. That’s best case scenario where the water is at full equilibrium - throw in some plant consumption, and non-perfect water circulation and you’ll be way down from that no matter what you do. I do think though maximising surface agitation for gas exchange is always beneficial in a low tech.

This post of Darrels gives some more detail on the CO2 numbers:

Hi all,

It is 0.6 ppm if you work from <"Henry's Law and the 415 ppm of CO2 in the atmosphere">.

We aren't entirely sure where the "3ppm value" came from, but there are threads about how it relates to the <"dKH/CO2/pH chart"> and the <"original 3 ppm reference">.

cheers Darrel

They do. It’s an impressive set up in the videos I’ve seen. Growing emersed makes much more sense commercially, due to that direct access to 400ppm CO2, and avoiding the issues of having to inject it, and deal with so much water etc. However, as per above, only a tiny proportion of that can be dissolved in water at equilibrium sadly. If physics allowed it to be 5%, none of us would have to mess around with CO2 injection!

 

[zozo]

I ended up buying one of the below and wired it up to a 12v plug i had hanging around. As it's a normally open solenoid, i put it on a double plug with the solenoid for my co2, that way as soon as the co2 solenoid turns on, the oxygen solenoid turns off and vice versa. Connected it up to the air line on my skimmer venturi. Works a treat and dont need another bit of hardware in the tank.

Normally Open Solenoid

View attachment 177367

There are also 3-way or 4-way solenoids that open the second channel when the first close. 🙂
www.aliexpress.com/item/1005002291695323.html?

www.aliexpress.com/item/4001216228059.html?