Why is it bad to aerate a planted tank

[Willyleigh]

I read that it is bad to aerate a planted tank and as I have fitted venturi onto both of my underwater filters I was wondering if I should remove them, what problems does the aeration cause?

[Drumachine09]

Plants need CO2 to grow. When you aerate a tank, you are dissolving oxygen into the water. That useless oxygen (to the plants) displaces the beneficial CO2, diluting it to levels that might make it hard to grow plants in.

[Willyleigh]

What about the fish though, don't they need the oxygen or do the plants provide enough oxygen for them?

[Chrona]

Dissolved gasses don't displace other gasses. An air pump merely causes a lot of surface disturbance, making it easier for the CO2 to escape. Normally, the amount of CO2 that will dissolve into the water is already very low, so aerating it will starve the plants of it.

Plants take in CO2 during the day and O2 at night, so if you wanted, you could run the air pump at night to make sure the fishes aren't starved for oxygen. During the day, plants will produce plenty of it to go around.

[Incredulous_Ed]

If you stop arating, you will probably notice and small boost in plant growth.

[sushant]

u don't need to worry abt 02 concentration if urs is a heavily planted tank.the only think to worry abt is ph balance if u r dosing co2 as it leads to lowering of ph.

[Chrona]

Although if you have a well buffered water (high KH content), then the change in pH with CO2 injection is minimal during the day

[sergo]

ok, i have 0 details on this so i'm going to ask a dumb question. what is the difference in the ammount of co2 in the air being pumped into the tank and co2 actually in the water? it seems to me that the air has a higher concentration than the water will have so why wouldn't get a rise in dissolved co2 from an air pump. also i know ph also plays a role in this so let's work with my ph of 7.6.

[Chrona]

ok, i have 0 details on this so i'm going to ask a dumb question. what is the difference in the ammount of co2 in the air being pumped into the tank and co2 actually in the water? it seems to me that the air has a higher concentration than the water will have so why wouldn't get a rise in dissolved co2 from an air pump. also i know ph also plays a role in this so let's work with my ph of 7.6.

Normally, CO2 dissolves into water very slowly from the air, much too slowly if you have more than 1 or two plants in your tank. With still water, the CO2 levels in the water will reach some equilibrium concentration - usually very low. When surface disturbance occurs, the CO2 leaves the water, because it is much easier for it to dissolve out than to absorb in.

Theres a chart online that you can use to determine the max amount of CO2 you water can hold using CO2 injections. It depends on acidity and alkalinity. Because most CO2 injection devices add an extraordinary amount of CO2 into the water (many many times more than is normal), you need to be careful, because an extremely high CO2 content is harmful. A normal CO2 concentration in an injected tank is like 20-30 ppm, so you want to adjust your alkalinity so that, adjusting for the slight drop in pH CO2 will cause, the maximum amount of dissolvable CO2 lies in the range.

[Rue]

...ohboy...

I got me some chemistry to learn...:help:

[sergo]

ah, i see.

[Lady Hobbs]

You probably have air heads attached to your UGF. If so, most of them come with a small plug to put in the hole instead of the airline. You will still get aeration making the UGF work just just not all those bubbles.

UGF don't work for plants anyway. Roots mess up the plates and it clogs.

About the bubble wands I don't know. I may have to remove them when I plant the tanks but I really don't see surface bubbles from them.

[kenyth]

Another way to add more CO2 and fertilizer at the same time is to add more fish. Personally, I think the fish are more important than the plants. My philosiphy is that the plants are there for them, so I make the environment as hospitable as possible for the fish. The plants just have to wing it. As far as UG filters go, as long as you use simple bunch plants with weak root systems like Anacharis, Hornwort, etc. Or use plants that float (Watersprite), or rely on bulbs or rhizomes, or even use potted plants, you're fine. I simply changed out to a grow light bulb and the Anacharis is doing great. The Hornwort, not so much, but it was in far worse shape when I got it. Most fish stores seem to do a good job of half killing the plants.

[Chrona]

Another way to add more CO2 and fertilizer at the same time is to add more fish. Personally, I think the fish are more important than the plants. My philosiphy is that the plants are there for them, so I make the environment as hospitable as possible for the fish. The plants just have to wing it. As far as UG filters go, as long as you use simple bunch plants with weak root systems like Anachris, Hornwort, etc. Or use plants that float (Watersprite), or rely on bulbs or rhizomes, or even use potted plants, you're fine. I simply changed out to a grow light bulb and the Anachris is doing great. The Hornwort, not so much, but it was in far worse shape when I got it. Most fish stores seem to do a good job of half killing the plants.

Adding fish does not add CO2. CO2 levels in a noninjection tank will always be 3-4 ppm, since the CO2 will escape the water faster than the fish put it in.

[kenyth]

Adding fish does not add CO2. CO2 levels in a noninjection tank will always be 3-4 ppm, since the CO2 will escape the water faster than the fish put it in.

Really? That's interesting. I would have thought animals would affect the CO2 level as plants affect the O2 level. I stand corrected. Do you happen to know if there is a dynamic in a natural setting that would allow plant growth to flourish, or does the 3-4 ppm level apply there too?

[Chrona]

Really? That's interesting. I would have thought animals would affect the CO2 level as plants affect the O2 level. I stand corrected. Do you happen to know if there is a dynamic in a natural setting that would allow plant growth to flourish, or does the 3-4 ppm level apply there too?

In nature, the deeper water contains high CO2 and low O2 levels, since there is no gas exchange with the air, and this water will circulate to the top with the seasons, giving plants the Co2 they need to survive. In most cases, plants are subjected to an average of like 10-15ppm of CO2, which is what most aquatic gardeners try to aim for. Plants add a lot of O2 into the water because it does not escape the water nearly as quickly as CO2 will. Lots of fish probably adds a decent amount of CO2 into the tank, but because tanks are so shallow compared to lakes and ponds, you (and the plants) won't notice a difference, as it all escapes rather quickly.

[kenyth]

thumbs2:

Thanks!