Much light without CO2?

[DudUser]

I now have a 250l planted low tech, with unknown Cryptocoryne, Hygrophilia polysperma and Limnophilia sessiflora. The crypts are doing fine, but the stemed plants grow to quickly up to the surface. No algae problems, but I thank my siamensis algae eaters for that.

Lighting is two 36W tubes, one grolux and one aquastar, on 12h per day. I'm thinking of adding two more 36W tubes and have on perhaps 10h per day. If I did this without also getting CO2, what would be the consequenses? Would there just be a algae bloom, or would the plants grow better?

I don't want to get CO2, pressure kits are expensive and yeast cultures smell to much for my small apartment.

[PeterGwee]

The light would not do the plants any good other than make them grow even faster to a certain point (You also run into the risk of CO2 limitation and outbreak of black brush algae if that happens). If you really want to improve plant health, adding CO2 is about the only way to do it. Since you do not wish to do so, you would have to live with what you have now.

Regards
Peter Gwee

[b_goh88]

The guideline for lighting is 2W per gallon. Any problem if lighting is less than this?

[kemp]

it just result in slower plant growth

[bclee]

It depends on your plants' need. If there are plants that require higher light level, you can try increase the lighting.

Personally, I am running a 50L tank with 51W (36W PL + 15W FL) of lighting without CO2. It is running fine without major algae problem. It is an easy tank to maintain.

The light would not do the plants any good other than make them grow even faster to a certain point (You also run into the risk of CO2 limitation and outbreak of black brush algae if that happens). If you really want to improve plant health, adding CO2 is about the only way to do it. Since you do not wish to do so, you would have to live with what you have now.

Regards
Peter Gwee

BTW, most non-CO2 tank are CO2 limited. If managed properly, it does not mean that CO2 limiting will cause algae problem. In my experience, BBA do not thrive in non-CO2 tank. No matter how I neglect my tanks, BBA just do not show up. Most of the time, green algae (hair, spot, etc) or BGA are the ones that plague non-CO2 tank if things go out of hand.


BC

[b_goh88]

I intend to add another light to my 4ft x 2ft x 2ft tanks. Any good recommendation. T5 or PL or others.

Currently, 4 X 36W PL (7000K)

[PeterGwee]

It depends on your plants' need. If there are plants that require higher light level, you can try increase the lighting.

Almost all plants are low light plants as long as you do not let them get overshadow by other plants and it does not fall below their light compensation point.

BTW, most non-CO2 tank are CO2 limited. If managed properly, it does not mean that CO2 limiting will cause algae problem. In my experience, BBA do not thrive in non-CO2 tank. No matter how I neglect my tanks, BBA just do not show up. Most of the time, green algae (hair, spot, etc) or BGA are the ones that plague non-CO2 tank if things go out of hand.

Yes, they are limited in a certain sense (They need approximately about a week or so to adapt to the low CO2 concentration via "up-sizing/down-sizing" of rubisco concentration accordingly). This is why non-CO2 tanks do best when water changes are stopped to stablize the CO2 content in a low range. Sorry for generalizing the BBA issue thing but some folks don't stop the water changes and their water source might well contain loads of CO2 (those that use well-water and etc) which is why they will problems with BBA. GS is more likely to be a problem if you blast it with loads of light and lets the CO2 "tank out". GS grows well when low in PO4/CO2 with respect to growth rate. Photosynthesis consist of two form of cycles namely the light dependent and light independent aka calvin benson cycle. This process tells you why it is best to lower the light once you limit CO2 since with loads of light, loads of chemical energy (ATP and NADPH ) would be produced for fixation of carbon in the calvin cycle. (Calvin cycle requires this two in order for carbon fixation to start.)

Regards
Peter Gwee

[DudUser]

Thanks for the replies. To clarify a bit I don't expect faster plant growth, I'm very pleased with the current rate. The problem is that the stemed plants grow to much upwards, sometimes with 5cm between the leaf nodes. This is not pretty, and what I want to get rid of. Perhaps I'll just redo the tank to root and moss...