maximum light without adding CO2?

[Elle2]

Hi,

I have been pouring over the posts and articles regarding CO2 and lighting (wish I had done that before buying my set-up) and I haven't been able to figure out what my maximum light should be before I have to start adding CO2.

I really don't want to get into the complexities of injecting CO2 so before I go and replace my very low light I thought I should find this out. I read that you can buy tablets for adding CO2- what are peoples' opinions of this?

My tank is 20 G by the way.

Thanks,
elle

[rich311k]

The general rule is once you get over 2 watts per gallon you need to start adding CO2, though you could strech that a little. Those fizz tabs are a waste of money. Since you have a 20 gallon tank you could also consider using Flourish Excel instead of CO2 and DIY is a good option with that size tank.

[Elle2]

oh interesting.. I was actually going to ask about that product... I saw on plantgeek.com that many plants don't do well with it... does this mean they probably require less CO2?

[rich311k]

Anacharis and some vals do not like it. I have corkscrew vals and the excel hasn't effected them that I can see.

[Purrbox]

Flourish Excel is not CO2, rather both are sources of carbon. Anacharis and Vals just happen to be sensitive to something in Flourish Excel, which is why it is recommended to be careful when using it in a tank that contains either of these plants.

[exodus]

I started dosing flourish excel in my 55g tank about 3 days ago. My 55 has 2.5wpg, and already I can see a difference in growth. My wysteria is absolutely exploding.

It does indeed work, just watch out for those two species of plants.

[kaz]

if I get 2wpg well I need co2? or it is over 2wpg that I will need it, like 2.5?

[Wizzard~Of~Ozz]

I found co2 helps at any light level. While it's nice to try and keep it simple, the fact is that the plants require carbon. If they cannot get it, they cannot grow. it is more important then light to a degree.. if Co2 in the water was 0, plants would wither and die regardless of light levels..

The 3 things required for growth (I'm not talking micros or macros, but the big 3) are water, Carbon (Co2 preferred by most plants) and light. The plant population dictates whether there is enough absorbed from atmosphere.

I read all the time "i don't want to get into Co2", well it is a requirement for plants to grow and typically it becomes the limiting factor even in sub 2WPG tanks.. the best time to add Co2 is when you add plants.. the best time to increase the lighting is when there are plants..

Excel is not a bad option for smaller tanks that don't have huge amounts of plants and relatively low-mod light.. but if the level drops because you missed dosing you may find yourself battling all kinds of green goo...

[7Enigma]

That's the point I wanted to reiterate again, that is there is no time at which CO2 needs to be injected, BUT you limit the chances of suffering a large algae outbreak if you suppliment with a carbon source.

I have the same tank as you and have a DIY setup. If I was to do it over again and only have ~2wpg I would definately go the Excel route. As it is, I have a 65w CF on the tank and so I would go through the Excel faster than would be financially sound.

You will see a noticeable difference at ~2wpg with CO2 compared to without. And it should be relatively cheap. If you decide to NOT dose CO2 or Excel, then you want as MUCH agigation of the water as possible (to replenish the dissolved CO2).

One final thing if you decide against using CO2, I'd recommend only 8-10hours of lighting per day, and if it were my tank, I'd break up the lighting periods into 2 per day (say on at 7am, off at 11am, on at 1pm, off at 7pm). This will give the water time to replenish the CO2 to ambient levels (2-5ppm CO2 depending on your source of info).

justin