Low-cost Plants

[jerky1280]

Right now I have a really low-cost setup. I have 6 adult swordtails, 3 fry, and 3 ottos. The plants are 3 amazon swords, a bunch of this grass-like stuff I got at petco, and some tall, thin leaves I pulled out of a river when I wanted some more plants but had no money. Substrate is store-bought gravel.

Anyway, I got the 10-gallon for free from a friend, bought a filter, a heater, and cobbled together lighting from two fluorescent desk lamps I had sitting around and some plexiglas from my school's shop.

Anyway, I was wondering if this setup could benefit from DIY CO2 or maybe air bubbles (I've heard that they are good at night)? I want to help the plants along, but not at the expense of my fish. Thanks guys!

[superjohnny]

If your water has a suitable KH, CO2 should help. People use air stones at night to remove excess CO2 because the plants don't use it at night. That's why people use solenoids on pressurized CO2 systems... to turn off the CO2 at night.

If you're looking for cheap plants find a group of fellow aquariests in your area... I'm always throwing away clippings and plants I don't like. That'd be a gold mine for you.

Hope that helps

[jerky1280]

Thanks for the input. I actually have a spare air pump sitting around, and a timer that I use when I'm out of town. Thanks for the ideas. Will running the air pump at night cause the CO2 levels to drop during the day? I guess I don't quite understand how CO2 and O2 act in water.

[125gJoe]

Originally posted by superjohnny
...... I'm always throwing away clippings and plants I don't like. Try selling some back to your LFS. We do that... Funny, our plants are in much better condition than the best supplier they can find -- so they have told us..and, from what we have seen for sale at that store. :)

jerky1280, do you have around 20 watts of lighting? DIY CO2 could work well for your tank.

[Starry]

Since no one else is volunteering this information....

CO2 is needed for plant photosynthesis. Without it, plants die. They take in CO2 only during the day, and O2 both at night and during the day. By using CO2 during the day, they release O2, which is nice for the fish. Not at night though.

When carbon dioxide dissolves in water, it dissociates into carbonic acid, a weak acid. You recall acids have a lower pH. So, more CO2 means more carbonic acid, which means lower pH. So, when you add CO2, pH drops a bit. Some people turn off CO2 at night, (or turn up surface agitation using air stones) to drive off excess CO2, to avoid too much of a drop in pH. Whether this is necessary depends on your particular set-up.

Got all that? Now, the extent of your pH fluctuations depends on your carbonate hardness (KH). The higher your KH is, the more your water will resist changes. ie. high KH = CO2 won't lower pH. Your KH should be between 3 and 9 degrees. Any lower, your pH swings will be too large, and pH may even drop too low. Higher than about 9, and I don't like it. People will tell you that high KH shouldn't be a problem. Doesn't matter too much right now.

To figure out your CO2 concentration, measure KH and pH at the same time. Then read the CO2 conc off a chart, like here:
http://www.thekrib.com/Plants/CO2/kh-ph-co2-chart.html
Note that their "safe range" is very conservative. You really need at least 15 ppm CO2, and up to 25 ppm is definitely OK. Also, KH tends to stay constant, so you may not need to measure it every time you test. Most of the time just do a pH measurement.

Well, there ya go. It'll be second nature soon. Good luck.

[Matak]

Hi Jerky
Your river plants sound similar to mine. Could you post a pic?

[Matak]

BTW, I run my air pump on a timer at night to release the CO2 from the tank, and then let it build during the day.