Alkalinity and PH w/CO2 Scrubbing

[Randy Holmes-Farley Verified Community Expert]

There is a risk of low O2 at night using a 100% recirc skimmer because you remove all possible oxygenation with it.

True, it is no worse than no skimmer, but aeration is, IMO, a primary benefit of a skimmer.

 

[Steve2020]

There is a risk of low O2 at night using a 100% recirc skimmer because you remove all possible oxygenation with it.

True, it is no worse than no skimmer, but aeration is, IMO, a primary benefit of a skimmer.

I agree aeration from a skimmer is a great benefit. That is one of the reasons why I also have outside air going to the CO2 Scrubber. Red arrows are the recirc air lines and the light blue is the outside air coming from the house fresh air return.

 

[Gatorpa]

Prior to running a recirc and no outside air I saw a .2 increase in PH but was going through media faster than I was hoping. Then I changed to a recirc without outside air and saw another .05-.1 increase ( maybe coincidence ) but saw a big increase in time between changing media. When I hooked up outside air along with the recirc I saw an Increase in PH to the point I had to add the electronic ball valve to control the PH because it was going towards the 8.5 PH range and I wanted to be conservative and not go above 8.4.
My ORP has been steady at 280-300. I don't want to get into a ticking match with anyone about recirc causing low O2. All I have to say is there are thousands of tanks that do not even run a skimmer and O2 is fine as long as you have some gas exchange via surface agitation or something similar. So what's the difference is all I'm going to say.
The media I ordered is from eBay due to free shipping. I just looked and it has gone up about $10 recently just like everything else. Still a good deal I think.

Fair enough, I watched a few videos of some guys for reef moonshiners talking about how it would drop O2, but was looking for real world experience.
They talked about using ORP to measure this, i figured if it wasn’t really valid someone would say something

 

[Gatorpa]

There is a risk of low O2 at night using a 100% recirc skimmer because you remove all possible oxygenation with it.

True, it is no worse than no skimmer, but aeration is, IMO, a primary benefit of a skimmer.

In theory if you used outside air and combined with recirc you would still be pulling in fresh O2 and likely a lower CO2 correct?

When talking aeration be it surface or via skimmer you would also be drawing in CO2 as well as O2, since in home CO2 if likely higher than outside CO2 bringing in outside air would maintain O2 levels as well as bringing in lower CO2 levels correct?

 

[Randy Holmes-Farley Verified Community Expert]

If you pull in fresh air as some fraction of the total skimmer air, the concern for O2 is reduced and might be eliminated.

 

[mandyvan]

Our CO2 scrubbers water was used up pretty quickly and needed more frequent refilling than expected. I like the idea of using less media, most of the media toward one end doesn’t get used.