Number of plants required in a small tank?

[x-router]

Hi,

Ok I have a small tank. I think it's 5-6 gallon (50cmx50cm 6 sided one). It's my first tank but so far I have been doing well with my fish and water. However my plants are a different matter. While I had read up a lot on fish and water before hand plants were an after thought...I just assumed they would grow.

I had two plants, one rotted a died, the other is hanging on in there but clearly not doing great. So I have replanted one of those fast growing ones that look like this:

I have ordered one of those haden CO2 gizmos and some plant food after reading info on here.

However first of all is my light unit any good? It's not a floresant but one of those long standard bulbs that came with my tank (30w). Do plants require a floresant light?

Secondly how many plants do I need in my tank to not have to use my air brick? Having read on here that they strip CO2 out of the water and the fact that I prefer the tank nice and calm I want to be able to do away with it. Will my two plants be enough?

When I get my next tank I want a working plant O2 generating system so this tank is my test bed for getting it right. The closer I can get to a working eco system the better.

Any advice would be great.

 

[Dubby]

At present your tank has 5W/gallon which is quite high (2-3W is the norm for easy growing plants). The higher the lighting the more you need to add CO2 & other additives to keep up the growth. In lower lighting conditions you can manage without CO2 etc.

Do you find your plants 'pearling' (giving off bubbles)?

Plants do not need flourescent lights. In order to Photosynthesize they prefer to use certain parts of the light spectrum (reds & blues). There are special tubes available that cater to these, but they are not the most attractive to the human eye. Hence people either use two bulbs - one bulb meant for plants along with a regular light or use a broad spectrum daylight bulb.

I woudnt worry too much about the equation of how many plants are needed to replace the airstone. As long as you have healthy plants, the fish are happy and the whole effect is pleasing to the eye, then that is what you need to aim for. You can easily achieve that with less than 60% of the tank being populated with plants.

Hope this helps.

 

[x-router]

I can't say I have noticed any 'pearling' but will have a good look tonight to check. I assume if I can't then they arn't doing well?

I don't think they do my light in any lower than 30w so I guess I will have to go down the CO2 route. I would think that more light + more CO2 = greater growth compared to lower light or is that not the case?

How do I know if the fish are doing well O2 wise I don't fancy the idea of turning off the air stone and waiting to see if the fish start floating to know if the plants are providing enough O2

 

[Dubby]

I can't say I have noticed any 'pearling' but will have a good look tonight to check. I assume if I can't then they arn't doing well?

Pearling is a sign that they are photosynthesizing very well. This cannot be seen very well in a lot of plants, but if you notice the odd bubble coming out when fish nibble at the leaves that is probably a good sign. Do you get a lot of algae in your tank?

I don't think they do my light in any lower than 30w so I guess I will have to go down the CO2 route. I would think that more light + more CO2 = greater growth compared to lower light or is that not the case?

Thats a pity. Yes. It also means more maintenance and in a lot of cases more algae The trick is to get the balance of CO2, light and nutrients right. Wish you all the luck.....

How do I know if the fish are doing well O2 wise I don't fancy the idea of turning off the air stone and waiting to see if the fish start floating to know if the plants are providing enough O2

Hmm.... I can imagine your concerns. Fish are more likely to die as a result of poor water quality than lack of O2. If you find fish gasping at the surface then you know that O2 levels are below par.

As long as you have a filter and there is some water movement on the surface, O2 will be absorbed into the water. What you have got to remember is that the air brick does not actually introduce much O2 into the water through the bubbles. It actually agitates the water surface thus allowing transfer of O2.

I would not be too concerned about using plants for just oxygenating the tank. Plants are probably more useful for reducing nitrate levels, providing some sources of food for veggie fish and giving fish a more natural habitat

 

[Magnus]

The answer is right here:

It's not a floresant but one of those long standard bulbs that came with my tank (30w).

30W of incandescant light is very low for any planted tank. You may want to switch it with a PC fluorescent bulb. I've seen daylight full spectrum bulbs on sale at Home Depot, Walmart and Lowe's. They bulbs are perfect for viewing (6500K-6700K), AND they're "made" for plants. FYI, "plant" bulbs aren't any better than your normal bulbs. It's the intensity that matters the most. Plus, plant bulbs look ugly on your plants anyways.

 

[x-router]

Hmm.... I can imagine your concerns. Fish are more likely to die as a result of poor water quality than lack of O2. If you find fish gasping at the surface then you know that O2 levels are below par.

As long as you have a filter and there is some water movement on the surface, O2 will be absorbed into the water. What you have got to remember is that the air brick does not actually introduce much O2 into the water through the bubbles. It actually agitates the water surface thus allowing transfer of O2.

I would not be too concerned about using plants for just oxygenating the tank. Plants are probably more useful for reducing nitrate levels, providing some sources of food for veggie fish and giving fish a more natural habitat

Thats very reasuring info. I have now turned off my air stone and the fish seem happy for the last 24 hours (and the tank is a lot calmer). I've also introduced some aquatic plant food and the haden CO2 is running plus I have ordered some small plants to go at the front of the tank that require lots of light.

Will post any changes

 

[Dubby]

Good point Magnus. Its back to school for me, got to learn to read properly

x-router, please read this Article on lighting so you can decide how much light you will need.

 

[x-router]

/me makes a trip to the lighting shop this weekend