Boston Aquarium Society Message Board

if I had the correct lighting and everything could I get away without running co2 on a 125 gallon tank with a lot of plants?

It all depends on the plants and your water
There are some plants that need CO2 and will do whatever it takes to pull it out of the water when you have high light.
I've had bizarre experiences with neutral/soft water and a high light low C02 tank - my PH would go UP, and up by a huge amount, but the water was unstable too. Nutrients in the water do play a big role too, so you might want to look into the needs of your plants (do they need iron? phosphate, etc.)

The other thing is that you can certainly do it but your plants will not thrive, and some of them might actually algae over or rot before they get any sort of size on them. My 55 gallon tank has a bright light , good substrate, and miniscule amounts of C02 - the val and hygro in there are doing pretty well but anything else is not.

In other words, you can certainly do it but to keep it from becoming a money sink, you might want to consider at least starting out with a yeast activated homemade C02 system, or pick up a couple of those nutrafin cannister things so the plants get some C02

Amy

Some people will say that if you have >3w/g lighting, you need CO2 injection. Don't believe them - it's a bit of a misunderstanding of how resource limitation works. Essentially, species vary at what level of CO2 concentration they can grow well at - this is an intrinsic trait of a species, not really dependent on the light level of your tank, although plants do alter their physiology under different resource environments, but very few plants are going to grow worse at high ligh/low CO2 than low light/low CO2 (excepting competition from other plants and algae). The point is whether the plants you're keeping are getting much benefit out of the higher light. Many plants will do fine under high light/no CO2 injection. But if you want your tank to look like an Amano or Dutch-style, you'll probably want to get pressurized Co2 eventually. The other major issue issue is algae-growth - if your plants aren't growing well enough to keep nitrates low (or quickly utilizing nitrates that you adding in fertilizer), you may get a lot of algae growth on the plants, which will further reduce their growth.

I initially tried yeast CO2 on my 75g (with 16Ow), trying up to 4x2L bottles, but I didn't see any detectable effect on growth, so I haven't had Co2 on any of my tanks since spring. Most of the plants I've tried have done well - vallis is thriving in all my tanks, rotala does pretty well (I think it's too shaded in my 75g), crypts are growing really slowly, ambullia died... Since there are so many variables in a tank affecting how a plant will do, IMO the best way is to just try out different plants, staying away from those that are supposedly difficult to grow or expensive. Also, surface/emergent plants are great since they get some or all their Co2 from the air.

HTH, Ryan

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Ryan Keane
100g mbuna
75g SE asian community
20g nano-reef w/ ocellaris clown pair
10g mbuna fry

I have 3 planted tanks without CO2. Granted, they are not AS lush as an Amano style tank, but its still very attractive, and folks who have not OD'd on gorgeous Amano-style online images are always impressed. The plants grow well, the fish are happy, etc.

The thing is, I'm doing my tanks "El Natural". In two, I have the Quackenbush setup - baked Georgia clay granules (aka kitty litter) with slow-release fertilizers, capped with FINE sand. This reduces the fertilizer from diffusing into the water column. The nutrient load in the water is minimal (anubias do not do well for me in these tanks) but the substrate demanding plants - crypts, swords and aponogetons really go to town. Hairgrass and stem plants do fine (just more slowly) and some floating plants keep the water column nutrients down. After the first 2 months of initial setup/settle in, I have had only minor algae outbreaks.

The third tank is also "El Natural", but using the Waldstad method. This one is relatively recent, but so far I'm really impressed. This is a layer of plain soil, covered by a layer of a larger grade of sand. This setup is even better, and the stem plants are doing well. (I think the clay base in the others does not provide enough oxygen for stem plants to root well).

The growth rate in all these tanks IS slow compared to an enriched tank. But, I do not fertilize, or have equipment headaches, I just feed the fish, and occasionally top off the evaporative water loss. I only vacuum the gravel every 6 - 8 weeks, and then, its mostly for aesthetics. Yep, you read that right! Its really, really easy! It may not be ideal for everyone, depending on your planted tank goals, but for someone like me, with a packed schedule and low tolerance for my hobby becoming yet another demand on my time, its great!

No, I'm not affiliated with the book person, I just read it and found it really intersesting, and scientifically sound. I have a marine biology education, and it was like reading a text book again, which I haven't done in years. But it was a GOOD read, too! Its called The Ecology of the Planted Aquarium, by Walstad.

I'm going to set up a 4th tank soon, this one will be 65 gallons. I'm definitely going to do the soil-based method. I'm convinced, LOL!

So, consider some alternatives if you're not able to get into the CO2 setup at this point in time! They're out there!

-Jane