20 gal light

[vartan]

Hy, im about to start a new high light tank and im concerned about the light. I got a 60x35x35 cm (24x14x14 in) 73 liter (~20 gal) Tank and a 2x55w PL light unit with built in reflectors. I will use pressured co2 and Ferts with EI method, and eheim 2322 + koralia nano for good flow. Sadly the lamps can only be turned on/off together, so basically i have to use 110 or 55 watts for ~20 gal. So its eighter 2.75 or 5.5 watt per gallon. I cant really decide, but since its my first high light tank i guess 55 watt should be enough. But on the other side im not sure if 2.75 w/g is enough for a thick HC carpet. I really dont want it to get leggy. I also would like a compact growth of: Alternanthera sessilis, Ludwigia glanduosa, Hemianthus micranthemoides, Riccia Fluitans, Rotala rotundifolia. Thanks for your help

Best regards Milan

 

[Gerryd]

Hi,

I would only go with the one bulb at first and see how it goes. You should easily get HC to grow if all ferts/c02/light is sufficient.

C02 is more the issue usually.......

You can always add the second bulb if not enough light which I seriously doubt, but if you do I would raise the fixture if possible at least 6-8 inches above the tank. The two bulbs would be WAY TOO much light for a 20 gal..........

Higher light = higher plant nutrient demand. This is c02, ferts,etc. The more light the more these things need to be stable and sufficient or algae will result.

As Tom keeps repeating, lower the light is the easiest way to control plant growth.

Hope this helps.

 

[vartan]

Thank for the advice. I was thinking to do about the same and go on with 1 bulb at least as long as the tank is not cycled. I was just not sure i can keep HC growing horizontally with 2.75 w/g because some ppl experienced that it wont stay down with such "low" light. Anyways i ll get eleocharis acicularis wich will surely carpet with this light when the HC turnes out wrong.