Some CO2 trials and tribulations

[fishb0ne]

10g planted tank
6 neon tetras
1 dwarf gourami
1 ghost shrimp
2 bamboo shrimp
2 small turbo[?] snails
a bunch of MTS

All plants are low-light plants, crypts, banana plants, anacharis.

Anywhoo, I set-up a DIY CO2 yeast generator but the first mixture didn't turn out quite well and was kinda unstable. For the first two days it gave off a bunch of CO2, then it started dying off. The blame was the yeast I used, a very old batch.

In any event, I started injecting on Monday. I don't have a test for GH or KH, but I have ordered one. All I tested for was pH. First day, over the course of the night the pH went from the usual tank's 8.3-ish to 7.8. It then went further down 5 hours later to a 7.6 and stuck there. Everything seemed good until 2 days ago when I noticed all my MTS and turbos were withdrawn in their shell. Then the one ghost shrimp left started acting distressed and the two bamboos went into hiding. I stopped the CO2 injection and did a 50% pwc. The fish are fine, the bamboo shrimp are fine as well, but the snails haven't come out.

I took a couple at random to see if they were still alive, I GENTLY poked them with a paper clip and they retracted further.
What do you think went wrong?
How should I go differently about things?
Any chance for my snails to recover?
Anything else I should do for my tank?

Well, the critters may be stressed and water a bit unstable but hey! At least I have lush green plants! Believe it or not, it made a noticeable difference in the brief 4 days of CO2 injection. My banana plants haven't had leaves for 3 months now and they suddenly all have 2 or more growing!
I plan on moving the floating plants and banana plants to a 2g bowl and start injecting there.

 

[neilanh]

WHen you saw everything acting funny, did you check your pH at that point?

It sounds to me like you're lightly planted, and you had too much CO2 being injected. A 10 gallon tank won't need a whole lot, and if your plants aren't consuming it and converting it to oxygen, then the O2 levels may have gotten very low in your tank. If it happens again, I'd recommend having an air pump on-hand and ready, as that is a quick way to get your O2 levels up in the tank.

 

[fishb0ne]

Someone correct me if I'm wrong but:
-lots of surface aggitation facilitates gas exchange, ie oxigenates water
-airstone/air bubbles doesn't oxygenate water THAT much, it's the water movement that does so, basically breaking the water surface
-CO2 injection does not displace oxygen and it would take a lot of CO2 to poison the fish.

But I do agree with you, the extra CO2 caused a pH/KH decrease, which stressed the inhabitants. It might also be that CO2 isn't used up fast enough, especially given that the plants are low-med light plants and the only source of light that I have is the [plenty of indirect] natural light and a puny 8-watt fluorescent lamp that's for looks, not so much plants.

Maybe I should switch to a more ineffective way of diffusing the CO2 to not have that much spread in the water. Perhaps an airstone and nothing else, rather than having the line hooked up to the filter intake

 

[neilanh]

You are correct, it's the agitation at the surface that causes the exchange.

I mentioned this because most people that setup a DIY CO2 system are highly concerned with maintaining CO2 levels of 30ppm or more, and in larger tanks this is very difficult with DIY. In order to help a yeast system accomplish this, most setup their tanks to have as little agitation as possible. When you do this, no O2 exchange is occurring and you're relying on the plants to produce the necessary O2 for your inhabitants.

That's what I was thinking could be the culprit.

 

[hashbaz]

That seems odd. Going from a pH of 8.3 to 7.6 would mean well under 30ppm of CO2. Do you know if the pH dropped further when your inverts started showing stress?

If you mix a CO2 batch with too much yeast it will produce very quickly and over a very short time. How much yeast do add? You may want to try using less.

 

[fishb0ne]

I used 2 cups of sugar, 12 cups of water [a bit much, I know] and 1 tsp yeast.

 

[hashbaz]

A lot of folks will only use 1/4 tsp yeast

 

[MyCatsDrool]

I run DIY CO2, and have been using it exclusively (even on large setups) for a few years now.

My experiences:

1.) I mix 1/2 gallon warm water, 1/2tsp baking yeast, 3 cups of sugar and 1/4 cup molassas (or honey, if I have one or the other on hand). This lasts me about a month or so.

2.) I run multiple containers, in 1 gallon milk jugs. I change out half of the containers on the 15th, the other half on the 1st of the month.

3.) I run 1 gallon of mix (1 jug) per 5 gallons of tank. (On a 55, I run 12 jugs, or 3x5 gallon water jugs)

4.) Check valves are critical, for ensuring that your yeast mix doesn't get into the tank. This can be disasterously messy.

5.) Because DIY CO2 is somewhat unpredictable, especially around the times I refresh the mix, I run airstones at night, every night, at lights out. I have a coralife timer system and have the lights on the daytime cycle and an airpump on the nighttime cycle. This ensures that the fish get plenty of oxygen at night, breaking up the CO2 at the surface. Plants do not use CO2 in their night cycle.

6.) Get or make a drop checker. You need something immediate to eyeball your CO2 level in your tank if you aren't using a solenoid to shut off your CO2. I made a drop checker out of an empty, glass brine shrimp egg jar and an old 3ml plastic eye dropper type pipette. I'll take a picture of it one of these days. Here is a great link to the basics of how to do it. Read the WHOLE thread. There are some SUPER easy to make ones in there. Make one. It makes all the difference. http://www.aquaticplantcentral.com/...aquarium-projects/32100-diy-drop-checker.html
If you aren't inclined to DIY one, go buy one. You can get the Red Sea one cheap at pretty much any fish store that carries planted aquaria supplies.

7.) get an airline control kit and put airline shut off valves on your CO2 lines, and use quality CO2 tubing. You need to be able to shut it off if your fish are gasping, and you don't want crappy tubing, because leaks SUCK. You might think it is your mix that crapped out, but 9 times out of 10, it is a leak somewhere. Leaks suck. Make or get a bubble counter too. You need one.

8.) Finally, I (and Travis both) run my CO2 high. I run 2 gallon jugs on a 5 gallon tank. I tend to be at about 45-50 ppm at any given time without problems for my fish. I have run upwards of 60ppm consistently at times. I start noticing problems at > 60ppm. This is where the drop checker comes in very handy. When it is yellow, I know I have a problem.

9.) Keep Flourish Excel on hand in decent quantities. Anyone doing CO2 injection should do this. If you are DIY, and you run out of mix, or you can't get your mix stable, or you can't get your CO2 up, or you are only running one jug of mix and need to change out solution, you will need to suppliment. Besides, it is just great for spot killing algae anyway. Just be VERY careful dosing it. I half the excel reccomended dose when I am running CO2. You can OD your fish with that stuff, easily. Even people with pressurized should have it on hand, for days when the tank runs out and they can't get somewhere to get a refill.

10.) Make sure you want to start dosing CO2. You are going to need light and ferts also. Make sure you have done all of your research, and have all of your equipment. Planted tanks are like life, or a three legged stool. THere are three parts to it...CO2, Light and ferts. If one is too big or too little, the whole thing comes crashing down. You have to have balance. So make sure you know what your plants and tank and fish need lighting and ferts wise also. Go over to the planted tank forum, post your tank stats, types of plants you have, and types of fish, and ask them what ferts and lights you need. post what you are currently dosing, your current test kit readings for everything you can test, and so on. They will tell you everything you need.

Good luck.

MCD