CO2 by natural means!

[hadjici2]

I have a 30 gallon tank (120 litres) with the following setup for the past 4 years:

1. Layers of substrate and fine gravel, which I don't know what the substrate is.
2. A driftwood
3. 3 species of plants that are hardy since they are the only plants that managed to survive a period where I completely neglected the tank. One of the species is Valesneria I think which is a fast grower, green leaved long plant. The other specie I think is Baby Tears or something. Forgive me for I do not know the names of the three species of plant I have for 3 years now.
4. Just purchased 4 mollies and recently one of them gave birth to around 20 babies.
5. kH 4
6. pH 8 - 9
7. One 25 watt Arcadia fluorescent lamp (Pink colour)
8. Two 25 watt Arcadia fluorescent lamp (White colour)
9. The tank has no top and the lamps are adjusted 30 cm above water level, where the depth of the tank is around 42 cm
10. Due to the hot climate in the summer, now my tank has a temperature of 31 degrees celcius and is not exposed to any sunlight at all.

Before I purchased the fish I had a DIY CO2 system with sugar and yeast but after reading a book I understood the reasons why my plants did not grow. Now that I have the mollies the plants grow better but I don't want to risk the fish by adding CO2 since many fish died because of this since I started this hobby. Now I am making a clean start and my vision is to create this balanced ecosystem with just mollies or any other community fish, many plants, no algae and no CO2 gudgets. I currently have hair algaem, thats why I added the mollies. The mollies didn't help much.

Why do I have a 1.2 ppm for CO2? This is the reaon why my plants don't grow I believe.
How many fish must I add to have enough CO2 and to maintain a balance so my tank doesn't get overcrowded?
How do I get rid of the hair algae? I suppose by having a healthy plant growth.

Please give me a few tips on how to create this ecosystem that I want. I have a limited supply of fish and plant species from my LFS.
My main task is ofcourse to increase co2 by natural means!

 

[George Farmer]

Fish do produce CO2 but in tiny quantities. Instead of stocking more fish to boost CO2 (and pollution) I would take a few simple measures to improve your plant growth.

Keep your filter output well below surface to minimise surface agitation. Agitating the surface will drive off any CO2 present - I assume this is why your CO2 is so low currently. You should get around 5ppm CO2 hopefully doing this alone. As as a guide the surface in my tank hardly moves. Don't worry about oxygen levels (unless you're overstocked) - the plants should produce enough oxygen for the fish.

It sounds like you have fairly good lighting, Arcadia Original Tropical and Freshwater Lamps. These are a good combination for a low-tech set-up. I would move them closer to your tank - a 30cm distance to surface would lose a lot of light I'd say. Do you use reflectors? These will improve intensity. Also how old are they? If they're older than 12 months then they will have lost a lot of their output and their spectral output may have changed - this will contribute to algae.

Lastly, why fear CO2 addition? There are some excellent cheap units out there i.e Nutrafin which are completely safe.

HTH

 

[hadjici2]

I will lower my lights....are 2 white and 1 pink fluorescent lamps ok or should I get 2 pink and 1 white?

My water surface does not move at all! I have an external cannister filter and there is no surface movement...

The plants are growing slowly but I want to lower the pH which reaches 9!!! This shouldn't be very good for my fish.....I have been running my tank with fish for 2 weeks....do you think the pH will drop at some point?

PS: my local water parameters are kH 4 and pH 9 just like in my tank, no changes in those parameters in my tank after 2 weeks time

 

[George Farmer]

2 Freshwater and 1 Original Tropical is the better combo IMO.

Something I missed earlier was that your are running 2.5 Watts per Gallon. With this amount of light you NEED higher CO2 levels i.e. 20ppm minimum, preferably 30ppm. This lack of CO2 with your lighting is undoubtably the primary cause of your hair algae.

I recommend buying 2 x Nutrafin units. When the sachets run out just use dried yeast and bi-carbonate of soda. Cheap and effective - no algae, lots of plant growth. If you can't afford them then go DIY. If you really don't want do inject CO2 then reduce your lighting.

Another benefit to adding more CO2 is that your pH will drop considerably. You say KH 4, pH 9 - I find that a little odd as most tap water has a higher CO2 content - if you are correct then your water has less than 1ppm CO2. Is your pH kit accurate? How old is it?

If you added say CO2 at 20ppm which should be easily acheived with 2 Nutrafin units then your pH will drop to around 6.8.