co2 Bubbles.

[KreativJustin]

Hello All,

I am currently considering adding a co2 system for my 75g planted tank. Still doing a bunch of research before making the plunge. I am currently lightly to medium planted, but my plants are reproducing and I want to add more in the future.

So what I've seen so far is that you should start with a lower bubble count (1-2bps) and then move up after 2 weeks if needed. Is the bubble count & diffuser determined by the water parameters or size of the aquarium in gallons? I was browsing amazon for a diffuser and it had 3 different sizes, and the one determined the size by bps and gallon size.

All help is appreciated, thanks in advance!

 

[Colin_T]

Have you got really bright light above the tank?
Do you add lots of fertiliser to the tank?

If you answer yes to both of these, then you can add CO2 if you like but unless you have bright light and lots of nutrients, adding CO2 won't make any difference to the plants, but will potentially cause the pH to drop by using up the KH in the water.

There is plenty of CO2 in an average aquarium. It's produced continuously by fish and filter bacteria.

 

[KreativJustin]

Hello again there Colin!

I use two of these lights:
https://www.amazon.com/gp/product/B0811QTHCM/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1

and one of these
https://www.amazon.com/gp/product/B07HFC7HV5/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

The two lights sit directly on the top. The grow light is hung about a foot above the aquarium, and is for the pothos that grow roots into the tank and for a cactus that I keep by my pothos from my mother in laws funeral.

I don't use liquid fert, only seachem root tabs for the rooted plants bc I use sand. My anubias nana just chills on a rock.

The reason I was looking into co2 is bc my anubias nana and my sagittaria subulata are starting to get tiny amount of little baby hair algae going. I had to cut the roots off of my pothos recently because it actually had a decent amount of hair algae growing on the roots and I really didn't want it to spread.

I just added a single algae eating shrimp (I will get more once the LFS gets more) yesterday and a flying fox to see if they will help with the little bit of algae I'm getting on my plants.

I have only about one dead spot in the aquarium, and it has no algae issues there. No plants are in the dead spot.

**EDIT**
I only use the blue feature on the grow light, and it does fill in the areas towards the back that the strips leds don't hit efficiently.

My ph and kv are high already for my area.

 

[Colin_T]

If you're not adding a lot of fertiliser, the algae is probably from too much light. You could try reducing the light by an hour a day and see if it helps reduce the algae.

Adding CO2 is unlikely to help with the algae.

 

[KreativJustin]

Right now I'm at 10hrs I believe, I'll dial is back to 9 tonight Thanks Colin.

 

[Aiken Drum]

10 hours is a lot of light. Its all about finding a balance between enough lighting for healthy plant growth and the amount of work you are willing to devote to cleaning algae off. This usually turns out to be 6 to 8 hours a day with the light on.

Trial and error is the way forward. Reduce it down to 9 hours see how things go. And you need to judge things over at least a couple of months as you wont see quick changes. Reduce the lighting period and see what happens over a couple of months. Then change it again, or increase/ decrease the amount of ferts you dose. Or try something else. See how things go for another couple of months. Then tweak something else.

Its important to change 1 thing at a time otherwise you have no idea what change caused what effect. For instance if you reduce the lighting period and increase the fertiliser, and things degrade you have no idea which thing you changed caused the degradation.

 

[KreativJustin]

10 hours is a lot of light. Its all about finding a balance between enough lighting for healthy plant growth and the amount of work you are willing to devote to cleaning algae off. This usually turns out to be 6 to 8 hours a day with the light on.

Trial and error is the way forward. Reduce it down to 9 hours see how things go. And you need to judge things over at least a couple of months as you wont see quick changes. Reduce the lighting period and see what happens over a couple of months. Then change it again, or increase/ decrease the amount of ferts you dose. Or try something else. See how things go for another couple of months. Then tweak something else.

Its important to change 1 thing at a time otherwise you have no idea what change caused what effect. For instance if you reduce the lighting period and increase the fertiliser, and things degrade you have no idea which thing you changed caused the degradation.

Ok, right now I only dose tabs and those will be on a 3 month schedule, so it'll be awhile before those get re-dosed. I do not use column fertilizer in here, and have no direct desire to unless things start seeming like they will require it. My goal is to not feed any algae in the open column, as that seemed to be a big issue in my 20g before I upgraded to the current 75g I'm in.

I'm still learning planted tanks and finding it super interesting, yet super frustrating too lol. I do not mind cleaning algae off my walls regularly but not so feasible with plants!

I do a once a week water change of about 20-30 gallons when I clean the poo off of the sand, I top off my tank every 2days (my tank is open with no lids)

 

[Aiken Drum]

Thing is, its about balance. Plants need nutrients, light and CO2. One of those 3 will be the limiting factor, and in most tanks thats going to be light or nutrients. Too much nutrients with insufficient CO2 or light your excess ferts will just feed algae. Increase CO2 without sufficient light or nutrients you just have an expensive piece of equipment bubbling CO2. Intense lighting or lighting on for long periods without sufficient nutrients or CO2, again algae.

From what you have described, low nutrients and long lighting period the light is the most likely cause of your algae. Reduce the lighting, see if it helps with the algae and see if it adversely affects your plants. Turning down the intensity if you have a programmable light, or masking part of the lamp with duct tape might also help with excess light.

 

[KreativJustin]

Thing is, its about balance. Plants need nutrients, light and CO2. One of those 3 will be the limiting factor, and in most tanks thats going to be light or nutrients. Too much nutrients with insufficient CO2 or light your excess ferts will just feed algae. Increase CO2 without sufficient light or nutrients you just have an expensive piece of equipment bubbling CO2. Intense lighting or lighting on for long periods without sufficient nutrients or CO2, again algae.

From what you have described, low nutrients and long lighting period the light is the most likely cause of your algae. Reduce the lighting, see if it helps with the algae and see if it adversely affects your plants. Turning down the intensity if you have a programmable light, or masking part of the lamp with duct tape might also help with excess light.

I have no programmable intensity. The light intensity of just the two 24" bars is actually quit weak. It penetrates the water and hits the plants nicely that are right under it, but it does leave dark areas around the tank. That is actually one reason I put the grow light above to help hit those areas the bar lights couldn't. Should I take this grow light off for the time being or leave it up and set it to the same 9 hour schedule?

 

[Aiken Drum]

I couldn't possibly say. Like i say trial and error. If you had a PAR meter (which are incredibly expensive) you could measure useful light across the bottom of the tank and adjust things accordingly. But thats just not feasible so trying things and seeing what happens over an extended period is the best way forward.

You could turn the grow light off, find it cures your algae problem but the plants suffer. Or you could reduce the amount of time the grow light is on to match your bars and find its not enough. The only way to know is to try.

Those 2 aquarium lights you have should be providing plenty of light for your low demand plants. You might get some darker areas at the sides if you are extending the 24" fitting to a 36" tank i suppose. But the solution isn't to add a 3rd light IMO. That grow light is designed for terrestrial plants, where CO2 is abundant and algae isn't a problem. The blue light will be promoting algae growth. Removing that would be the first thing i would try in my trial and error exercise.

 

[KreativJustin]

I couldn't possibly say. Like i say trial and error. If you had a PAR meter (which are incredibly expensive) you could measure useful light across the bottom of the tank and adjust things accordingly. But thats just not feasible so trying things and seeing what happens over an extended period is the best way forward.

You could turn the grow light off, find it cures your algae problem but the plants suffer. Or you could reduce the amount of time the grow light is on to match your bars and find its not enough. The only way to know is to try.

Those 2 aquarium lights you have should be providing plenty of light for your low demand plants. You might get some darker areas at the sides if you are extending the 24" fitting to a 36" tank i suppose. But the solution isn't to add a 3rd light IMO. That grow light is designed for terrestrial plants, where CO2 is abundant and algae isn't a problem. The blue light will be promoting algae growth. Removing that would be the first thing i would try in my trial and error exercise.

I'm going to remove that grow light and do 9 hours Thanks for your help Aiken.

 

[Aiken Drum]

While PAR is a far better indicator of how useful the light will be for growing plants, lumens can get you in the right ballpark. You want 10 to 20 lumens per litre for low demand plants. Each of those light fittings gives out 1500 lumens, so 3000 in total. So those 2 light fittings together are good for a tank between 150 and 300 litres.

If this is the 75g (300 litres) you have mentioned previously those 2 lights together should be good for your tank if you arent trying to grow anything to demanding.

Like i said lumens are not great measures because it doesn't take account of whether the light is useful or arriving where its needed, but PAR meters are expensive.

 

[Caliban07]

Have you got really bright light above the tank?
Do you add lots of fertiliser to the tank?

If you answer yes to both of these, then you can add CO2 if you like but unless you have bright light and lots of nutrients, adding CO2 won't make any difference to the plants, but will potentially cause the pH to drop by using up the KH in the water.

There is plenty of CO2 in an average aquarium. It's produced continuously by fish and filter bacteria.

Co2 won’t use KH. It doesn’t work like that.

 

[Caliban07]

As mentioned, you probably don’t need co2. Never ever focus on what is happening to older leaves. Only new leaves. You said the plants are propagating so is there really an issue. Are the new leaves green, nicely shaped and large? Or are they pale, twisted and small?

Unfortunately, lumens we just cannot use to determine effectiveness for plant growth. The unit of lumens is how bright a light is perceived by the human eye. That is literally it.

Also blue light doesn’t cause algae. This is another unfortunate myth that lives on and on.

The question is, can the plant successfully carry out the process of photosynthesis. If yes, the plant will grow new leaves. If the answer is no the plant will die.

Bubble rate is useless for checking co2. You need a drop checker. Do some research on those first if you decide to add co2. Co2 will make things much easier as far as growing plants is concerned.

 

[Colin_T]

I'm going to remove that grow light and do 9 hours Thanks for your help Aiken.

Don't do both at the same time. Either reduce the lighting period to 9 hours a day and see how it goes for a few weeks, or stop using the grow light for a few weeks and see if that helps. If you do both, the light would be significantly less and you could harm the plants.

 

[Colin_T]

Co2 won’t use KH. It doesn’t work like that.

Carbon Dioxide (CO2) is an acidic gas that can drop the pH of pure water. If there is little to no carbonate hardness (KH) in the water, the CO2 can drop the pH of an aquarium very quickly. Aquariums that use supplemental CO2 normally have a KH around 80-150ppm to prevent sudden drops in the pH.

 

[Caliban07]

Carbon Dioxide (CO2) is an acidic gas that can drop the pH of pure water. If there is little to no carbonate hardness (KH) in the water, the CO2 can drop the pH of an aquarium very quickly. Aquariums that use supplemental CO2 normally have a KH around 80-150ppm to prevent sudden drops in the pH.

Co2 does drop pH but has no bearing on KH or vice versa. They both exist as part of an equation based on pH. In a tank without injection the proportion of co2-bicarbonate-carbonate is dependent on pH. When you add more co2 the pH changes but it doesn’t use the buffering capacity like other acids. It’s difficult to wrap your head around even when explained as simply as possible but co2 injection will not use up the buffering capacity.

People are running tanks with 0KH and injecting co2. All they need to measure is a 1 point pH drop in the water and that will give you 30ppm co2. The drop checker works by adding a solution of 4dKH in to a glass chamber separated from the tank water. The co2 gas diffuses in to the 4dKH solution and drops the pH turning the solution green which is the colour that indicates 30ppm co2. This is the standard target for high tech planted tank owners

 

[Colin_T]

Any acids in water are neutralised by carbonates and bicarbonates. The KH (carbonate hardness) is made up of carbonates and bicarbonates. Therefore Carbon Dioxide (CO2), which is an acid, drops the pH of the water, The KH neutralises the acids and helps to stop the pH dropping further. If you have 0 KH, then the pH can drop rapidly when CO2 is added. A small amount of CO2 is unlikely to affect the pH, but if the CO2 levels go up, the pH can crash down. I have seen it happen in lots of tanks.

 

[Caliban07]

Any acids in water are neutralised by carbonates and bicarbonates. The KH (carbonate hardness) is made up of carbonates and bicarbonates. Therefore Carbon Dioxide (CO2), which is an acid, drops the pH of the water, The KH neutralises the acids and helps to stop the pH dropping further. If you have 0 KH, then the pH can drop rapidly when CO2 is added. A small amount of CO2 is unlikely to affect the pH, but if the CO2 levels go up, the pH can crash down. I have seen it happen in lots of tanks.

I think this is one of the best ways I can find to describe it.

‘It is only when you add CO2 (H2CO3) as your acid that the dKH doesn't change, because you are adding both HCO3- and H+, they are conjugated acid and base pair. If you add another acid, like hydrochloric (HCl), you've added an H+, but the anion is a Cl- and your dKH falls. When you add a base like sodium bicarbonate (NaHCO3) you've added a HCO3-, but the cation is Na+ and the dKH and pH rise.

If your base is sodium hydroxide (NaOH), pH and alkalinity will rise (you've added an OH-) but dKH will stay the same’

I think the confusion lies where when you add co2 to water you are not adding just the co2 it becomes carbon acid H2Co3



So when you add co2 the dKH doesn’t change.

 

[Caliban07]

This might also help to make this easier to understand.

‘The important bit is that this is an equilibrium, as we add CO2 we reduce pH, but we don't reduce alkalinity, and as CO2 levels fall 2HCO3- (bi-carbonate) and Ca++ (calcium) ions will come out of solution as the salt "limestone" = CaCO3, add more CO2 and the limestone will dissolve, releasing bicarbonate and calcium ions, remove CO2 and CaCO3 will precipitate out, on and on for ever in equilibrium (assuming we have some dKH).

This is only true when adding co2. Add co2 in to hard water the pH drops and carbonates go in to solution keeping the dKH stable. As the co2 gasses off the pH rises and the carbonates precipitate out. The dKH is always there and isn’t used up.