Heavily planted tanks - what happens during night?

[yhbae]

If you have a high-light heavily planted tank, I assume they will consume alot of O2 during the night and produce CO2 - could this suffocate fishes? Also, since the level of CO2 will rise, couldn't this affect pH as well?

I was always curious about this...

 

[David]

I'm pretty sure plants use some oxygen, but mostly CO2. They would not cause an imbalance in your O2 and CO2 levels, but I may be wrong.

 

[Phantom Thief]

Plants do the opposite of photosynthesis during the night and use oxygen and produce carbon dioxide. But i wouldnt think it's a serious matter though, there are many heavily-planted tanks out there, and no one has lost a fish from suffocation yet

P.T.

 

[David]

Ok thanks for clearing that up. I am relatively new to live plants so I learn somehing new every day

 

[Bangin]

Many people use an airstone at night to prevent any problems with excess CO2.

 

[smithrc]

it can be a major problem if your using a CO2 system - this will increase the difference between CO2 and O2 levels during day and night - and can cause PH swings over night.

we've not had any problems though.

 

[Lateral Line]

I've never had any trouble. In water that is adequately buffered, the pH won't move much. Running an airstone at night is rarely necessary, and if it is, generally indicates overstocking.

 

[Phantom Thief]

A good filtration rate is all you need

P.T.

 

[yhbae]

My water isn't well buffered - pH = 7.2, KH = 3, GH = 5. I never had issues with buffering in normal tanks where you have normally stocked fishes with some plants, but in heavily planted one, I'm not sure anymore...

Also, do plants take up any components of KH? i.e. Could they reduce the buffering capacity of water when they absorb nutrients? If this is the case, is it necessary to supliment with baking soda?

 

[smithrc]

i must be well buffered then (I've never tested) as our PH dosnt shift from 7.4...

 

[fishlover900]

if you are still worried why don't you have an air pump and stone and put o2 into the water

 

[tear-scar]

The night-day cycle DOES cause a fluctuation in PH and oxygen levels. The problem for the fish to handle is not so much the level of oxygen, because the plants produce huge amounts of oxygen in the day compared to their consumption at night, but rather its the drop that may be stress-ful. Most fish coexist with plants though, and are used to the natural cycle and fluctuations of CO2 and O2. Problems may occur because aquarium water is already super rich in nutrients because the keeper has to accomodate the plant's need for CO2 and other nutrients in a smaller space, so the night day cycle may cause bigger fluctuations due to CO2 fertilization in an aquarium. The night time air-stone addition will help to replenish oxygen at night, and keep fluctuations smaller.

 

[yhbae]

So in theory, I could use a timer and automatically turn on the airstone during the night if needed... Hmm... It seems strange that this isn't more common if indeed is a problem for heavily planted tanks...

Thanks for the feedback, guys!

 

[Silly me]

Plant I have a fairly well planted tank with a DIY CO2 system and 4wpg and a lots of fish
5 black widows
4 SAE
2 Flying foxes
1 elephant nose
4 Paradise fish
4 cory's
1 female betta

the there is no airstone, one external Eheim Pro canister filter. all in a small 30gallon tank..

Never had a fish gasping or air? and the PH shifts from 6.8 at night to 6.5 in the morning..

I have to remove any floating plant from the tank to stop the paradise fish from breeding any more, the cory's are fat from tetra eggs and I had 2 corys breeding on the side for the glass 3 weeks ago..

so the PH shifts cant hurt them to much?

here a look a my fairly well planted 30G
the rosy barbs was removed 2 days ago as they eat the new growth of the plants
even is they eat a great amount of beared algae

 

[yhbae]

Hmm... May be I should stop worry and go ahead...

This tank does contain many fishes however - over 30 if I remember correctly, and I do water change every two days currently.

"Silly me", how much light do you have, and do you do DIY CO2? Which plants do you grow in your tank?