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CO2 injection for 55 gallon tank

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Hey everyone!

I have a question regarding the size of a regulator for Co2 injection on my 55 gallon tank. I am looking to get injection going but don't want to drop $300 on a regulator. Would the UNS mini be able to provide enough Co2 into the tank? I definitely want the dual stage aspect and a reputable brand. 

Any insight is always appreciated!!

- Joe

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Would it work? Probably but you would likely be refilling your tank so much that little bit of cost savings will quickly be offset by refills. There are plenty of regulators that handle 5lb+ co2 tanks for way less than $300. I'm not sure where you are looking at them. Check out Co2 Art. They have a duel stage regulator for $150. The Co op used to sell their regulators but have since stopped because they were taking up too much time from customer support I think.

For a 55 gallon tank I used to run a 5lb co2 tank. It would last 3-6 months if I recall correctly. I lived very close to my refill location though so how long it lasted was less of an issue.

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Thanks for the info. I've tried to look at everything I could find online for the regulators. I definitely plan on using at a minimum a 5lb cylinder. The UNS mini says it fits onto all different types of cylinders from disposable to the CGA320 fitting on big tanks. I guess I am more curious to whether the size of the regulator has any bearing to the size of a aquarium. My idea is that I really doesn't matter since you are counting the bubbles regardless. Does that make sense at all? 

My plants are definitely growing without CO2 but I am having a terrible time with staghorn algae. My Monte Carlo definitely needs the CO2 boost as well. 

- Joe


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Thank you @Jack.of.all.aquariums and @Mmiller2001 for the input. I purchased the CO2Art pro se regulator. To minimize cost for now I am going to try running it off a 20oz paintball cannister. I will update how it goes once everything is set up and running.

From what I have read, the co2 injection should help combat the staghorn algae issues in addition to ramping up growth on the plants. Is this info correct? I have been pulling out at least a handful of it every few days. It is terrible in the Java moss! Really hopeful that I can dial it in to boost the growth/health of the Monte Carlo, Anubius Nana petite, and the Reineckii's (Normal Alternanthera and Variegated).

- Joe


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  • 2 weeks later...

Follow up:

I purchased the CO2Art regulator and all the peripherals for it. I have it running off a 5lb cylinder on a smart socket. 

Algae has kicked into overdrive!


I am at a loss right now. My best guess is not enough flow in the tank. I currently have a Marineland Magniflow 220 right now. I just built a makeshift spray bar to beef it up until I can buy a larger sized cannister filter. I've been trying to dose ferts according to the directions. The Co2 system was running at 1 bubble a second. I also started a chemiclean treatment yesterday which is probably pointless. 

Anyone have any other helpful insight? 

Here is the post I made with all the other equipment:

Best regards, 


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Hey Joe,

I briefly read your other post with the specs on your tank and it looked like you have been changing around your lighting schedule a bit? I just wanted to ask what does that schedule look like now? Also I wanted to ask if you were dead set on keeping that kind of schedule doing the siesta and what not. are you running two lights?

What is your dosing schedule looking? Could you kind of break what your dosing looks like between each water change? I couldn't remember if it was a weekly or biweekly schedule. whats the co2 schedule like and is it on a timer?

But i'll put the general husbandry aside for the moment and try to address the algae. It looks like most if not all of your plants are fully covered in some kind of algae.

You probably will not like me saying this but I think a good way to go is a hard restart. You could try to fight it slowly, that works perfectly fine but if it were me I'd try to take one day to do alot of the heavy work and then try to focus on the small details later. Whatever day you choose to do maintenance maybe give yourself a little more time in that day to attack this head on.

I would definitely start removing as much algae as you can by hand or with a toothbrush. If you can see new growth I would just look keep the tops of your stem plants and throw out the rest. If you're not too sure if your plants are healthy enough at least cut out all those leaves that are covered in algae, those can't be saved. I know a bare stem looks really ugly but as long as you diffusing co2 correctly and have some fertilizer your plant will come back in no time.

I realize I'm proposing a rather drastic measure and  many people dont like doing huge overhauls. If you'd like I don't mind trying to dissect whats going on in your tank with you otherwise i'll stop drilling you with questions haha

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Thank you for the response! (Thank you @Mmiller2001 as well. I did read that article) 

I am definitely not dead set on the siestas. Here is my current lighting schedule:


I was also running the Nicrew light mimicking the fluval schedule via a smart plug. I have since taken that light out of the equation when the algae really went nuts. 

Fert Dosing:

I was using the flourish line of ferts prior to adding the Co2. Excel, Flourish, Flourish Advanced, and Iron. Excel was daily, advanced was daily, iron was every other day,, and flourish was 1 to 2 times a week.. I bought the UNS "all in one" a few days ago and have been following the every other day directions of 1 pump per 10gal. I definitely noticed the algae increased with the UNS fert. I put flourish root tabs in about 2 months ago. 


I only started running Co2 5 days ago. I have that on a smart plug coming on at 7am and shutting off at 9pm. I have it set to 1 bubble per second in the bubble counter. I also have the air pump on a smart plug that was shutting off while the Co2 is running. Air would come back on through the night. The Co2 appeared to be diffusing through the larger UNS glass diffuser pretty well. I notice that the entirety of the disk wasn't diffusing. The Co2 only comes out of a small portion of the diffuser disk area. The drop checker would be green by the end of the day though. Definitely don't feel confident in how that system is running though.

I will definitely be doing a hard restart like you have suggested. I did do something close to that around 2 months ago where I did a bleach dip on the Reineckii's to kill some algae. It somewhat worked for a little while. The stag horn algae has been terrible. I probably have pulled out 3 or 4 softball sized piles of it over the past month. Feels impossible to get it all. I also tried the spot dosing of Excel on algae with no avail.

I removed a great deal of the Java Moss already and trimmed the vandelli down by half. The majority of the reineckii's seem like they might be too far gone. The Monte Carlo is having no problems growing. The crypts and Vals are growing fine. The Anubius Nana petite is covered in the stag horn. It also might be too far gone. Java moss was a bad idea. 100% admit that one. 

At this point if I can't get it beaten back, and dialed in, I feel like I might have to "Nuke" it and start over. 

Your insight into my mess is greatly appreciated!

- Joe 

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Thanks for sharing the lighting settings. That's your culprit. You are running a fluval 3.0 at full blast on these plants for over 14 hours a day. That's a lot, way too much even if you were going whole hog on CO2. I'm running a single fluval 3.0 on a 24-inch tall tank, with fairly heavy CO2 injection and E.I. daily fertilization, and my peak lighting period is less than half that.   Adding CO2 into the mix, maintaining a medium level of fertilization, probably is making the algae worse. Algae is caused by an imbalance of nutrients, light, and CO2 -- sometimes it can be tough to identify the imbalance, but luckily in this case it's obvious the light is the problem.

I do recommend taking a day for a hard restart, at least manual removal of as much algae as possible. Drastically reduce your lighting asap. Start with "Bentley's Day Sim" settings here: https://imgur.com/a/CTIjYYu  

Fertilize daily or as often as you can (not a full dose: the point is to spread out the dosing, giving the plants enough time to use the nutrients before the algae can take advantage).

Do this for weeks/months, observing growth. This isn't going to fix everything, but it's going to put you on the right track. If you start seeing algae, you'll know something is out of balance, but at that point it probably won't be so far out of whack that the algae is uncontrollable.

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Ok so this will most likely be a long read but I'lll try to keep it as organized and concise as I can. I'm gonna touch on a few things that stick out to me within your system that could be problematic but thing I want to address is setting a baseline with your lighting, fertilizing, and maintenance schedule. A lot of things I mention will be merely suggestions or just the approach I would take in your situation don't think of it so set in stone and I'll try to offer other solutions that could fit your needs.


First thing would be your lighting schedule. I'm not too familiar with fluval 3.0 interface, i may be reading it wrong but I think you have it ramp up and down? Theres not really with an issue with ramping up/down the lights maybe i'm reading it wrong, the 11:30 and 12:30 times are confusing me. 

What I see is that you do have a siesta mid day, it looks to me for about 2 and a half hours. I asked earlier about that just to see your reasoning behind the siesta. Most people run double cycles in a day with a siesta in between usually to allow buildup of co2 that the plants release when lights are off. Now you could still run that siesta cause maybe those hours you set are to accommodate your work schedule or whatever may be and those are the times you can view your tank. The problem is the how long the lights are off. Usually most people give at least 4 hours rest time if they plan to go this route. I find that it takes some time for the plant to switch from photosynthesizing to sleep.

This will kinda of get into a pseudo science and I have absolutely no way to prove this, but I think the plants sleep cycle is just as important as the photoperiod. Sure plants do some growing when the lights are on but I notice especially with my own plants 2-3 hours after lights off I can literally see that my stem plants have gotten taller. It seems to me that plants tend to eat all day when the lights are on and when the lights are off use that energy grow. I think rest time is just as important as photoperiod and we should try to strike a balance with those 2 phases. It looks like in total your lights are on about 14 hours give or take? Think of it this way, can humans work 14 hours a day with a small nap in between? Sure, but over prolonged periods of time, that stress begins to weigh on you.

That aside, seeing that you can inject co2, I really see no need for a siesta if it were for the purpose of building up carbon.  If this lighting schedule is to cater your own schedule, I would suggest at the very least give the plants 4 hours rest time and possibly 4-5 hours lighting periods. (When I tried it i did 4 hours on 5 off 4 on and didn't really like it because the tank ph was swinging alot throughout the day)

I personally would just do 8 hours only until your problem is gone and then look to adding incremental if it isn't enough. And for your lighting spectrum i would suggest to go back to whatever the standard plant spectrum is for now. But thats very minor, If you happen to like the way it looks keep it and see.


So you should definitely find one dosing regime and stick with it for now and do everything at the recommended. Wether it's Seachem or UNS all in one it doesn't really matter but I think you can get into a whole lot of problems by say adding one thing from here or one things from there. If there isn't a strict guideline that you follow there will be absolutely no way to track if your missing a certain nutrient.

I haven't had any experience with the UNS all in one fert but nowadays I feel like ferts in general are more comprehensive  than they used to be. Just the headache of trying to figure out nutrient deficiencies its so much easier to do a pump of fertilizer where it gives just about everything plants would need. I would say do the low light dose of 2x a week and 30% water change first until you see your tank start to come back and be sure to do the water changes. The water change is key to remove any leftover nutrients so that algae can't use any of it. This part isn't set in stone because once your plants begin to thrive you'll be able to give more to push growth but right now you should focus on limiting extra nutrients for algae to uptake.

Now you could also go with Seachem but the two problems I see in arsenal is your missing the Nitrogen, Phosphorous, and Potassium bottles. I've used this dosing regiment and it works fine but I feel like its so much more confusing on how each dose of ferts is not standardize. A capful for each of their fert is for a different tank size and it makes it more confusing than it should be. So if you do go this route I really suggest getting the NPK bottles, advanced, trace etc. I really do think if you listen to anything just stick with the all in one, just look at how much of a nightmare the seachem dosing schedule looks like.


Also I noticed on your water test you didn't have any visible nitrates which is an issue itself. A lot of people like to think overdosing fertilizers is the cause the algae which really isn't the case if you keep up with water changes. I think why your plants are struggling to beat out your algae is because there is at least nitrogen deficiency possible phosphate and potassium too. Since your plants were limited so much they couldn't use the rest of the micronutrients in your system leaving for the algae to eat. If you go Seachem make sure to get the NPK bottles and try to follow that schedule but definitely just for ease i'd really recommend just doing UNS. Make sure that by the end of the week your nitrates are atleast withint 10-20 ppm by the end of the week. If it isn't continue with the water change schedule and try adding a little more.


This part will be very general cause it can get really technical but I can help you out with that once you resolve the algae

From what you've said it sounds like co2 is being dissolved into the water so this part should be short. You could leave it for now but if you want to further optimize I would say don't tweak co2 pressure since it seems to work and play with the timing. You mentioned that your drop checker turns green at the end of the day which means some co2 is present. Keep in mind that the drop checker is usually an hour or two behind on its reading. So say at 6 PM your drop checker turns green, that means you achieved optimal saturation at 4 or maybe 5 PM.

This part right here is VERY IMPORTANT If you do this, you really need to keep an eye on your fish. You can set your co2 to turn on an hour before lights turn on to start that buildup and have it turn off an hour before lights off. If you do this be sure to keep an eye on your fish for the next two weeks. Continue with using the airstone at night just to gas off the rest just to be safe. Bubbles per second isn't really a good measurement for diffusion but atleast we know carbon is present and rising at a slow rate.

Right now either stick with the schedule you have or have co2 turn on an hour early for atleast a couple months. they way you should manipulate the co2 is just by changing the time frames, it gets really dicey when you play with the pressure. Any changes that you make should be done in very small increments and allow atleast a week or two to see if there were any negative effects.

Sidenote: when you see the co2 bubbles come out of your diffuser you want to see the bubbles slowly drift upwards, you don't want it to fly straight up.


Theres definitely alot more I should address but I think these topics have more of a holistic approach. Theres still a lot i"m struggling to remember. If you can take away anything, once we standardize our routine maintenance, issue become more apparent and we can pinpoint certain problems.

This would be how i run my schedule (you don't have to follow its more of a reference to visualize the timeframe)


Use Only the Fluval 3.0

Co2 turns on: 11:00 AM              Co2 off: 7:00 PM

Lights on: 12:00 PM                    Lights off: 8:00 PM


UNS all in one

dose: Monday and Wednesday the recommended dose 

waterchange: Saturday 30-40%


Follow something like that for atleast 2-3 months because thats how long it will take to see the effect of that change. From there any changes you do make you only change one part of that schedule and see what happens. If you get more algae go back to your old schedule.


Hopefully I didn't bore you to death with this long rant, I really hope something in there can help you with your problem or give you a better idea of what could be happening. If theres any part that doesn't make sense just ask me 

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  • 3 months later...

I wanted to give some update pictures! Thank you to everyone who gave me pointers a few months back. I definitely have it dialed in now.


Biggest changes were/are:

Super OCD removal of every bit of staghorn I could find. Almost 100% removal of Java Moss. Addition of 6 Siamese Algae Eaters, and a few more Amano Shrimp. 

Increased the flow with a wave pump.

NO  FERTILIZERS used anymore! I had stopped them to try to get the plants to uptake the Nitrates. The plants have totally flourished without ferts!!!

One pouch of Fritz Max Out. This added in controlling the Nitrites. 

Automated the curtains in the bay window with 2 switchbot curtain motors. Curtains are closed prior to daylight and opened at dusk.

Other automations are done via smart outlets for 2nd light, co2, and air pump.



Co2 injection. (Co2 Art Pro-SE regulator, Co2 Art tubing,10lb cylinder, and Co2 art Bazooka Flux diffuser.)


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On 12/26/2020 at 11:12 AM, Adsfm_joe said:

Hey everyone!

I have a question regarding the size of a regulator for Co2 injection on my 55 gallon tank. I am looking to get injection going but don't want to drop $300 on a regulator. Would the UNS mini be able to provide enough Co2 into the tank? I definitely want the dual stage aspect and a reputable brand. 

Any insight is always appreciated!!

- Joe

I bought a co2 art one for my 56 gallon. It’s not the ultra premium one, and I can’t add multiple co2 lines to other tanks. It has worked great. Although I heard the fzone ones on Amazon are okay. 

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