CO2 Scrubber-should I get one?

glb · Jun 21, 2018

I know you shouldn’t chase pH, but I just watched the BRStv episode about scrubbers and wonder if I should get one. My pH runs between 7.8-7.9 in my 40g fowlr tank. Alk is 11, Ca 490. It’s going to be an LPS dominant tank and I’m planning ahead. I’m almost positive it’s a CO2 issue. An air line outside is impossible. I’ve been seeing info that corals calcify better at a higher pH. What does everyone think?

pluikens · Jun 21, 2018

Do you have the option of opening up all your windows for a day to see if you ph jumps up? Seeing this let me know that CO2 was the issue in my house. I now run a scrubber and have air pulling from outside because I was using too much soda lime for my liking pulling inside air. It's only been a month of so and I haven't had a chance to see if the CO2 scrubber is helping beyond pulling air from outside. I did see it work when scrubbing inside air, though (about 0.3 or 0.4 increase)!

Scorpius · Jun 21, 2018

7.8-7.9 is fine. If you want run a fresh airline to your skimmer, but your ph is perfectly acceptable.

Diznaster · Jun 21, 2018

How do you measure pH and how often? I'm about 3 months into a 90g cycle fowdr. Started dry rock, gradually adding fish, eventually someday adding corals. I have 2 calibrated pH probes that always agree with each other and also somewhat closely match test kits. When things get crazy both probes show massive swings across the day. Especially for a few days if added a new fish or changed something, (increase possible bacteria load, etc..) I have had 8.1pH at 8pm and 7.9pH at 8am, or 8.0pH at 8pm and 7.6pH at 8am. I totally agree it is a CO2 high causing pH low. Yes increasing Alk can increase pH, but your already at 11 on the upper end, so your CO2 is probably high. I just added a CO2 scrubber a couple hours ago. It is on an air pump in the sump before the bubble trap and I plan to use it when pH is below 7.8 or when on battery backup. If you are holding 7.8-7.9 all day long I would suggest being happy with that. If you drop below 7.8 around the time of lights on (morning), you probably need less CO2. A CO2 scrubber can be pretty cheap to try, it cant hurt. That's why I am trying one. Same as you running outside air line is not practical, but I also have a hard time completely blaming ventilation for my low pH. I know it is high acid from probably/mostly CO2, but it can come from other things too. I'm a noob at marine aquariums so take my input at that level, but I'm also a plan/do/check/act... data driven type. I'll try to let you know what my Scrubber did in a couple days.

Randy Holmes-Farley · Jun 22, 2018

I think a scrubber is a fine thing to use when raising pH is a goal. Your hard corals may grow faster, but otherwise that tank may not look appreciably different. [emoji3]

glb · Jun 22, 2018

Scorpius said:
7.8-7.9 is fine. If you want run a fresh airline to your skimmer, but your ph is perfectly acceptable.

Will corals grow more slowly at a lower pH?

glb · Jun 22, 2018

Randy Holmes-Farley said:
I think a scrubber is a fine thing to use when raising pH is a goal. Your hard corals may grow faster, but otherwise that tank may not look appreciably different. [emoji3]

Thanks Randy!

glb · Jun 22, 2018

pluikens said:
Do you have the option of opening up all your windows for a day to see if you ph jumps up? Seeing this let me know that CO2 was the issue in my house. I now run a scrubber and have air pulling from outside because I was using too much soda lime for my liking pulling inside air. It's only been a month of so and I haven't had a chance to see if the CO2 scrubber is helping beyond pulling air from outside. I did see it work when scrubbing inside air, though (about 0.3 or 0.4 increase)!

Problem is I live in South Florida and the heat is pretty bad this time of year. I could take a cup of tankwater outside and check it that way. Thanks!!

glb · Jun 22, 2018

Diznaster said:
How do you measure pH and how often? I'm about 3 months into a 90g cycle fowdr. Started dry rock, gradually adding fish, eventually someday adding corals. I have 2 calibrated pH probes that always agree with each other and also somewhat closely match test kits. When things get crazy both probes show massive swings across the day. Especially for a few days if added a new fish or changed something, (increase possible bacteria load, etc..) I have had 8.1pH at 8pm and 7.9pH at 8am, or 8.0pH at 8pm and 7.6pH at 8am. I totally agree it is a CO2 high causing pH low. Yes increasing Alk can increase pH, but your already at 11 on the upper end, so your CO2 is probably high. I just added a CO2 scrubber a couple hours ago. It is on an air pump in the sump before the bubble trap and I plan to use it when pH is below 7.8 or when on battery backup. If you are holding 7.8-7.9 all day long I would suggest being happy with that. If you drop below 7.8 around the time of lights on (morning), you probably need less CO2. A CO2 scrubber can be pretty cheap to try, it cant hurt. That's why I am trying one. Same as you running outside air line is not practical, but I also have a hard time completely blaming ventilation for my low pH. I know it is high acid from probably/mostly CO2, but it can come from other things too. I'm a noob at marine aquariums so take my input at that level, but I'm also a plan/do/check/act... data driven type. I'll try to let you know what my Scrubber did in a couple days.

I have an apex ph monitor so it monitors 24/7

glb · Jun 22, 2018

Ps-I don’t have lights on the tank yet so I’m sure that affects ph as well.

glb · Jun 22, 2018

Here’s the last 24 hours and the last week. I dose alk at 10pm and 12am.

Randy Holmes-Farley · Jun 22, 2018

glb said:
Will corals grow more slowly at a lower pH?

Depends on other factors too, but generally, it is published in the scientific literature that lower pH can lead to lower calcification rates by hard corals.

Randy Holmes-Farley · Jun 22, 2018

glb said:
Ps-I don’t have lights on the tank yet so I’m sure that affects ph as well.

Yes, photosynthesis will tend to drive up the tank pH. The effect can be large.

pluikens · Jun 22, 2018

Randy Holmes-Farley said:
Yes, photosynthesis will tend to drive up the tank pH. The effect can be large.

^^This. I wouldn't be worried about getting your pH above what it is until you have lights. Do you have a refugium? That can help off hours when your display lights are off.

glb · Jun 22, 2018

Randy Holmes-Farley said:
Yes, photosynthesis will tend to drive up the tank pH. The effect can be large.

I’m thinking about buying “starter lights” before I add coral to see if that helps. I want an ATI T-5 setup eventually. My guess is that a fowlr tank isn’t that affected by lower pH, but I’m using this time to really dial in stability and good maintenance habits. Or maybe I just want some cheap box store lights because it would make the tank look better, lol. It would help with coralline right? I started with dry rock and don’t really have any yet. The tank has been up for almost a year. I have two LED track lights on the ceiling over the tank but my guess is that doesn’t really count as far as ph.

glb · Jun 22, 2018

pluikens said:
^^This. I wouldn't be worried about getting your pH above what it is until you have lights. Do you have a refugium? That can help off hours when your display lights are off.

I don’t have a refugium or display lights yet. Just house lights. The tank is on a 3-5 year plan, lol.

glb · Jun 22, 2018

Here’s my setup. All DIY and I’m proud!

pluikens · Jun 22, 2018

@Randy Holmes-Farley Correct me if I'm wrong but won't lights only help if there's either algae or coral present for photosynthesis to occur? Better lights may not increase pH unless the tank is stocked with an organism which utilizes photosynthesis.

Randy Holmes-Farley · Jun 22, 2018

pluikens said:
@Randy Holmes-Farley Correct me if I'm wrong but won't lights only help if there's either algae or coral present for photosynthesis to occur? Better lights may not increase pH unless the tank is stocked with an organism which utilizes photosynthesis.

Yes, but any lit tank will have at least some algae or cyanobacteria to photosynthesize, even if you have not added any corals yes.

But, yes, the effect gets bigger as you have more and more photosynthesizing creatures