Confused about CO2

[janene]

I have a planted tank and I'm confused about whether adding CO2 injection is a good or bad idea at this point. I have a test kit for O2 and this weekend it was a little low, so I had to throw in another bubble wand for my fish to be happy. But I don't think my plants are very happy and I'm trying to understand why. They have a lot of algae growing on the leaves, mostly brown, but getting some green. They grow *great* and I have to trim them often, mostly stemmed plants. I also have an anubias nana that's doing ok and an amazon sword that's doing mediocre, starting to look a little pale, but it might need transplanting to get more of the light. I do have some strong lights, but haven't added up the total wattage. Oh, it's a 150, btw. I fertilize about once a month as they really don't seem to need it, growing like crazy. The fish like to beat them up, though, so they look a little holey, oh well, have fun, guys. I'm also seeing algae growing in my large canister filters, and have to switch/clean them monthly which seems a bit too often (I only do one at a time, btw, and I have 2).

I also had a hard time getting the ground cover to root and grow (hornwort sort of stuff, almost all dead/leafless).

Should I add CO2? I have all the materials, just haven't done it because it seemed like I would just be making the O2 matter worse?

Janene

 

[RedTurquoise]

Well, you have touched a big topic!

First, we need to know how much light you do have! In low light tanks, C02 is not necessary. However in higher light tanks, it is required. When adding C02, you have to ensure no surface movement otherwise the C02 will dissipate.

The reason your lacking in 02 is because your plants seem to be suffering. You mention they grow but yet the leaves turn pale, perhaps yellow. Your plants should have no trouble supplying the necessary 02 for your fish however that does depend on how many plants you have. An interesting fact is that plants can store nutrients then will there is a lack of nutrients, use up their stores. Algae does not store nutrients hence fast response/growth. Therefore providing constant nutrients will ensure healthy and proper plant growth.

The other side is once you start adding C02, you must increase the frequency of ferts. In my 90G with C02 injection, I fert every 2 days! The bottom line is maintaining a balance between light, ferts and C02. When increasing one factor, the other 2 must follow.

However, if you think your plants are doing great, I would not change anything. Changes usually encourage algae growth until the balance is met again, then the algae get outcompeted by the plants. You will always have algae growth however keeping it to a minimum is the goal. A tip regarding this is not starving your plants!

 

[Avalon]

Well said Red

It sounds like you lights may actually be hurting your plant growth. The more amount of light you have, the faster the plants [/i]want[/i] to grow, but when they grow faster, they must have food, and this comes in the form of nutrients (fertilizers) and CO2.

Yellowing of leaves is a nutrient deficiency, paritcularly nitrogen. I've been doing a lot of experimenting in my 100 tank. It's low light, 160w normal flourescent + sunlight from a big window.

Growth was very slow with very few ferts. I've since added CO2, 40mL of Tropica Master Grow per week, and dry potassium supplements. I have a full fish load and change 20-40 gallons of water each week. Growth has picked up significantly. The swords are looking healthier, the crypts are getting huge, and the chain swords are spreading rapidly and growing very tall. I also have 5-6 foot Vals (adds to the jungly look!). There is no significant algae; the leaves are pretty much algae free.

My conclusions and advice to you:

- CO2 helps in almost any condition.
- The more light you have, the more nutrients must be supplemented, and the faster plant growth you will have.
- Fertilizers should always be supplemented; the faster the growth, the more you add and vice versa.
- Higher light will cause algae growth to increase when CO2 & nutrients are not kept on par.
- You need to test for nitrates and phosphates. Potassium, Iron, and trace nutrients are guestimated.

 

[janene]

Thanks Red and Avalon.

So it appears that I maybe should turn off one of my lights, one that I added a couple of months ago and actually caused some problems... and maybe do the CO2, and cease with the bubble wands, which kind of scares me as I had to add the first one in an emergency situation (right after I added the brightest light btw).

Avalon, what kind of setup do you have that the Vals work ok? I have a home-made system with a tall intake pipe that "skims" the water surface and 2 smaller output pipes a few inches from the surface. Makes it really hard to have anything long and drapey in there as it gets into the intake and slows down water rate. I had some water lettuce floating around in there and I finally threw it all away in disgust as it was always in the way (and didn't grow roots very well, I think the fish ate them).

Before I do anything, though, I'll report back with the wattage, tonight when I get home from work.

Thanks, guys!

 

[Avalon]

I have a basic 100g, the five foot version. I have my filter output and a powerhead on the left end, and the vals are on the other end. The outputs and the vals are in the back corners on either end. The powerhead puts out the most water current, and I have it positioned so the current reflects off the front glass and circles around on the right side. This circulation grabs the vals and pushes them from right to left. Looking down on the top of the tank, the circulation goes in a counter-clockwise direction.

I have a 50/50 mix of Flourite and small gravel. I don't use root tabs. The vals took a while to take root, but once they did, they grew alright. After I added the CO2, they really began growing! They also began blooming--they make these little pod things that shoot pollen (or seeds, whatever) out everywhere. I just got through pulling out about a half a five gallon bucket worth of clippings. I like when they grow out--they drape and flow over the tank like a canopy. The only bad thing is that they block the light, but it doesn't seem to be a big problem.

My lights are just 2 48" shoplights ($16 each@home depot), staggered, with one GE Sunshine (Chroma 50) and one GE Ultra Daylight in each fixture ($6 each@Wal-Mart). I've thought about adding another one, but things are growing just fine, so why bother?