Taking the plunge with Co2

[marchmaxima]

Up until now, I have resisted the temptation to turn my low-light 15G (2 ft) tank into something with a little more light which requires CO2.

As much as I love my plants, I'd dearly love to re-scape it with a fresh look. It's starting to look like a great big mish-mash of stuff in there with no real structure. Allegedly, there's fish in there too

So, I have ordered a 2 x 24 T5 HO light fixture that'll output 3.2 wpg and will implement DIY CO2.

However I'm a bit nervous and I need some advice. Out of the tap, the KH is 1dKH. The water in my tank is 1dKH. The tank GH is 6dKH. If I implement CO2, my tank is probably to experience a decent PH crash. PH is currently 7 (or just under).

What are my buffering options? I have been to the LFSs in the past and looked for some sort of shell grit to buffer the water, but it's always packaged with no label and have no idea if it's the stuff I need. I also have three marble (I think they're marble) rocks in there. Supposedly they were supposed to raise KH. Evidently they have not.

Any advice on the issue greatfully received.

 

[marchmaxima]

PS. Do I need a bubble counter?

 

[fort384]

Sharon,

I had a gas separator hooked to my diy system that doubled as a bubble counter. This kept floccuated yeast from entering the tank.

I don't think the low KH of your water will present a problem. I have read many times from many sources that fish are not as sensative to a pH change induced by CO2. This is evidenced by the fact that tanks not utilizing a pH controller fluctuate as much as +- 1 on the pH scale on a daily basis as they cycle through the photoperiod, with no effect to fish.

 

[Jnam]

Ph change caused by the consumption of buffers is what will cause undue stress to your livestock. The Logorithmic change of your PH due CO2 as Fort384 said will leave them feeling just fine. No buffers needed.

You dont need a bubble counter but they are helpful in tuning your CO2 system. the best you can do is test your KH and PH and determine your CO2 levels from that. I use a drop checker to monitor the CO2 continuously

 

[marchmaxima]

Thanks for the reply Fort

As it happens, I'm planning on using a second 600ml bottle as a gas separator.

Also, one more question the articles I've read didn't make clear. Assuming I use 2 x 2 liter bottles which is recommended as a way to ensure a more constant CO2 generation. The idea is to change out one bottle at a time.

When you first set it up, do you get both going at the same time? If so, at what point do you change out the first bottle? Do you use less mixture in the first bottle or a weaker yeast mix?

 

[Jnam]

I stagger mine by 1 week. and maintain +/- 30ppm on the co2 in my 55 gallon.

I use 1 teaspoon of yeast and 1cup of sugar and 1/4 teaspoon of baking soda and just less then 2L of water. For my mixture.

I mix my yeast in warm water and let stand for 5 mins before adding to sugar water.

Works great for me.

 

[marchmaxima]

Okay, I just re-checked my tap & tank water.

Tap: pH = 6.8, KH = 1dKH
Tank: ph = 6.8, KH = 2dKH

I looked at the CO2 chart here CO2 Chart

Says that I have around 6ppm CO2 in my tank currently (am I reading that right?)

So I know I want to aim for approx 15ppm CO2 concentration. I assume this is monitored by the pH / kH values?

 

[Jnam]

You are correct

 

[fort384]

I would aim for higher than 15 ppm. Unstable co2 below 25-30 can leave the door open to bba. I experienced this in my tank with only 1 bottle. I think with 2, you will be in the sweet zone on your tank with no problem.

 

[marchmaxima]

Okay, 25ppm - 30ppm it is.

After a visit to the other side of the city, I now have:

2 x 2L drink bottles I need to consume, 600ml buddy-sized bottle for gas chamber, 2 check valves, 2 bubble counters, silicon tubing, t-shaped connector, elbow connector, funnel, raw sugar, yeast and bi-carb.

Now all I need is my lights to arrive.

 

[Smitty]

I would aim for higher than 15 ppm. Unstable co2 below 25-30 can leave the door open to bba. I experienced this in my tank with only 1 bottle. I think with 2, you will be in the sweet zone on your tank with no problem.

I'm working on DIY CO2 as well so I hope you don't mind me asking.... what is bba? Since adding the CO2 (I only did 1 2l, guess I need another one?) I've had a big spike in a green algae looking thing on my plants. I will say the growth has been spectacular.

 

[fort384]

Black beard or black brush algae. It isn't all black as the name implies. Check out the algae resources in the plant resources link in my signature below. Lots of pics to help u id the algae, and pointers for treatment based on the algae u have. If u can't id it post a photo and someone here can help u out.

 

[Purrbox]

If you weren't injecting CO2 yet, then your CO2 couldn't have been above 3ppm. Since it was only reading at 6ppm, I would suspect a testing error. If not, then this means that the CO2 formula won't work on your aquarium.

 

[marchmaxima]

No, I'm not injecting CO2 yet. I was estimating the current CO2 level using on this chart...

CO2 Chart

My ph is currently 6.8 and my KH = 2dKH - I was reading the wrong line I think when I said 6ppm. In reading it again, I get just under 10ppm. I also plugged in my numbers to the calc here Measuring CO2 levels in a Planted Tank and this seems to suggest 9ppm, although I do notice you are only supposed to use it if the water is carbonate buffered which mine is not.

But if you suggest that reading above 3ppm are not possible in a non-co2 injected tank, then what am I doing wrong?

I am so confused

 

[Purrbox]

You aren't necessarily doing anything wrong, it just means that you can't use the chart because there are buffers present that are messing with the results. Your situation is why it's an excellant idea to use a drop checker to measure CO2 levels.

 

[marchmaxima]

Okay. So I need a drop checker....

 

[fort384]

Sharon,

A drop checker will only work if you use a specific dKH solution in the checker, just FYI. If you put your aquarium water in there, it will not give you a reliable reading due to the buffers in your water.

 

[marchmaxima]

Thanks fort. I just ordered one online. If I can't figure it out from the instructions, I'll come back here.

 

[marchmaxima]

Okay, I am now in possession of my new lights and a drop checker.

The instructions on the drop checker say to 1/2 fill the inside of the drop checker with aquarium water and to put 4-5 drops of the CO2 regent in it, turn the thing upside down and secure it into the aquarium. aAfter a while, I'll the flud inside the checker will turn to one of three colours.

If I do this, will I get an accurate reading? Fort, you think this won't work?

 

[fort384]

It will work, it just may not be accurate. Your water contains unknown buffers that can throw off the reading. The most accurate method is to use a reference solution that is of a known kh value and contains only sodium bicarb as a buffer. The most common is a 4dkh solution as this will indicate green at ~30ppm co2 which is a good target.