What Time For Eheim Skimmer 350?

[mastin]

Would y'all recommend I run my Eheim 350 skimmer at night or as slipfinger suggested he does on his 75g "weed farm" for: "half hour runtime multiple times a day" (https://barrreport.com/threads/75g-dutch-weed-farm.14313/). I've been reading posts where Tom emphasizes again and again CO2 levels such that I'm thinking I'd better attend to any surface agitation. Then I saw slipfinger's statement that he has his skimmer on a timer and thought this a good idea. I can't imagine either timer choice would be significantly superior or inferior, both should help, but I thought I'd solicit opinions before I setup my timer. 12hrs on and 12hrs off or say 30min on every 2 hours? Or maybe someone might suggest this skimmer has little to no impact CO2 levels?
thank you

 

[Kyalgae]

I would say on a smaller tank, like my 20g long it can have a large effect on CO2. I've played around with my skimmer more times than I should have. On full flow it can take my CO2 out of a good range quickly. I run it one click off of minimum flow, and I just run it all day, I found my CO2 fluctuates too much when I used to turn it off and on multiple times a day on a full flow setting, it was easier for me to get a constant CO2 with constant, lower skimmer flow. Right now I have mine come on when the CO2 starts, and stay on half an hour after the CO2 stops.

 

[mastin]

Thank you for your thoughts.
Why have it on when CO2 is on?
I understand you have found a minimum flow on the skimmers works well for you.
But, if the objective is to not have an effect on CO2, why not turn it on at night rather than during the day?

 

[Kyalgae]

Thank you for your thoughts.
Why have it on when CO2 is on?
I understand you have found a minimum flow on the skimmers works well for you.
But, if the objective is to not have an effect on CO2, why not turn it on at night rather than during the day?

I get surface film on the water, and during the day this reduces the amount of O2 available to my critters. If the skimmer wasn't operating during the CO2 period, I would have to inject less CO2, or risk killing off my shrimp. The livestock are much happier with it operating during CO2 injection. I have it for the livestock, and I like the look of crystal clear water on the surface.

 

[mastin]

I understand. Thank you kindly for your response.
I've just started to approach CO2 more carefully.
In the past I've only used a drop checker.
Now I have a reasonable Ph meter and am waiting on my Hanna Alkalinity kit to arrive.

 

[mastin]

Hanna Alkalinity kit arrived.
It reports a reading of 36 which seems to be in units of CaCO3
and according to the manual to convert to dkH I * by .056 for a result of 2.016 dkH.
Now I'm planning to use the data provided in this thread "Co2/ph/kh Table".
According to the table at a dkH of 2 and pH of 7 I would have 6ppm CO2.
A target might be a pH of 6.3 yielding 30ppm CO2?
Does this seem reasonable?
I use RO water and add GLA's UGH Booster.
I understand there are relevant variables such as lighting and goals, I'm just wanting someone to confirm my math and general understanding of this table.
Thank you,
David

 

[Christophe]

Your math adds up, but the table doesn't take into account anything that's in your water other than carbonate/bicarbonate, so it isn't particularly an accurate representation for YOUR tank water. Many of the things in your water affect the pH other than carbonates, and it would be one seriously complicated set of calculations to try to chart it out. Never mind the chart, it's just another way to convince yourself that your CO2 is better than it actually is!

You'll do plenty good enough if you periodically de-gas some of your water for a day or two, then measure the pH with a decent calibrated probe. Then, you just need to add enough CO2 (and diffuse it effectively, and circulate it effectively) to consistently drop the pH by 1.0 or so, when measured by that same probe.

 

[mastin]

Wow that seems like great advice Christophe!
I've always used an atomic CO2 diffuser and never really worried much about it other than having about one bubble a second.
But, I'm pretty sure that if I really want to move my pH by more than a quarter of a point I'm going to have to increase this.
I've read some people suggest that inline diffusers are much more efficient do you or anyone agree?
thank you David

 

[Kyalgae]

I’ve only ever used an inline diffuser. The thing is, the deeper you have it in your plumbing the more time the little bubbles have a chance to come together into larger ones. After they get too big they just rise to the surface and pop as they exit the outflow tubing. The more gas you push into it the more gets wasted on ejection. I would say they aren’t very efficient by themselves. I now use the inline diffuser to feed a Sera 1000 reactor. I’ve never had a chance to use an in-tank version, I shied away from it because I didn’t want to clean it often. Feeding a reactor with an inline works better for me than feeding the reactor with regular bubbles. I feel like I have a limited amount of pump power in my setup, so the larger bubbles would fill the reactor fast and I would get a very large co2 buildup inside it. With the inline diffuser it breaks things down before the reactor, and I think it makes it easier for things to dissolve. I get a very fine misting of co2 in the tank, but not enough to detract from the tank, and the bigger bubbles get dissolved in the reactor. I’m definitely not an expert, because I’ve really only tinkered with this single tank setup. The combo is more effiecient for me. Others have used inline diffusers to feed regular reactors, like Edelry.junior. Then again you have Nuno M using an in tank diffuser and getting great results.

Over in Fablaus 20g journal there’s a couple videos of his co2 setup, and I posted a vid of what it looks like when you feed your sera with and inline diffuser.

20gl shallow tank - Plant Farm

TL;DR: Long story short there’s more than one way to skin a (CO2)cat. If I had to bet a nickel I would say the in tank version of the diffuser is more effiecient than the inline, because the bubbles have more space to expand, and dissolve. When they are in the aquarium tubing they come together into larger bubbles that don’t dissolve in the water as well.